Optimized Uhf Antenna Design, Simulation, and Implementation

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OPTIMIZED UHF ANTENNA DESIGN, SIMULATION, AND IMPLEMENTATION

APPLIED TO RESIDENTIAL HVAC MOTORS

A Thesis

Submitted to the Faculty

Purdue University

Arik L. Straub

In Partial Fulfillment of the

Requirements for the Degree

Master of Science in Engineering

August 2013

Purdue University

Fort Wayne, Indiana

For my uncle, Mike Straub, who steered me towards Electrical Engineering, and my father, Jim Straub, who has instilled his work ethic and a strong desire for higher learning

in me.

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ACKNOWLEDGMENTS

Firstly, I’d like to thank Dr. Eroglu and Dr. Pomalaza-Raez for their help and work in advising me. It was with their guidance, expertise in radio frequency and communication protocols, and focus throughout the research that made this project possible. Next, I’d like to thank Dr. Walter and Dr. Cochran for their help and teachings in Systems Engineering, which brought an interesting new aspect and viewpoint to my project. I’d also like to express gratitude to the National Science Foundation for the monetary support during my research, and funding of conference attendances. Most importantly, I’d like to thank my fiancée, Katrina Heckman, and my family for their unwavering support, love, and help throughout my life, my studies, and my future.

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TABLE OF CONTENTS

Page

LIST OF TABLES ...... vi

LIST OF FIGURES ...... vii

LIST OF ABBREVIATIONS ...... xii

ABSTRACT ...... xiii

PUBLICATIONS ...... xv

1. INTRODUCTION ...... 1

1.1 Objective of Study ...... 1 1.2 Standard HVAC System ...... 1 1.3 Wireless Communication...... 3 1.4 Overview of Thesis ...... 4

2. SYSTEM ENGINEERING CASE STUDY ...... 6

2.1 Problem Definition ...... 6 2.2 Functional Design Decomposition ...... 8 2.3 Design Constraints ...... 11 2.3.1 Size constraint ...... 11 2.3.2 Minimize cost of product ...... 13 2.4 Design Decisions...... 13

3. ANTENNA SIMULATION AND VERIFICATION USING HFSS ...... 14

3.1 Simulation Simplifications and Excitations...... 15 3.2 Test Board VNA Measurements and HFSS Simulation Results Comparison ...... 17

4. ANTENNA PROTOTYPES AND TESTING ...... 20

4.1 Simulation Simplifications ...... 21

Page

4.2 Comparison of Prototype VNA Measurements and HFSS Simulation Results .....22 4.3 LQI and Range Measurements ...... 26

5. ANTENNA DESIGN AND OPTIMIZATIONS ...... 29

5.1 F-Antenna Theory ...... 29 5.2 Ground Plane Size Variations ...... 31 5.3 Stacked Antenna Variations ...... 34 5.4 Antenna Array Variations ...... 36 5.5 Ideal Antenna Design Recommendations ...... 42

6. HVAC ENVIRONMENTAL EFFECTS ...... 44

6.1 Encapsulation Material ...... 44 6.1.1 Encapsulation material simulations ...... 45 6.1.2 Encapsulation material with water simulations ...... 47 6.2 Control Board Enclosure ...... 49 6.2.1 Control board enclosure simulations ...... 50 6.2.2 Control board enclosure with connector simulations ...... 57 6.3 Simulations Including All Environmental Factors...... 60 6.4 Recommendations ...... 62

7. CONCLUSIONS ...... 64

BIBLIOGRAPHY ...... 66

A. FUNCTIONAL DESIGN DECOMPOSITION OF WIRELESS HVAC MOTOR.... 68

B. LQI AND RANGE MEASUREMENT TABLES ...... 75

C. ANTENNA OPTIMIZATION SIMULATION RESULTS ...... 79

C.1 Ground Plane Variation Simulations ...... 80 C.2 Stacked Antenna Simulations ...... 83 C.3 Array Simulations...... 86

D. ENVIRONMENTAL EFFECTS HFSS SIMULATION RESULTS ...... 90

D.1 Encapsulation Material with Water Layer Simulations ...... 91 D.2 Control Board Enclosure with Polymer Connector Simulation ...... 94 D.3 All Environmental Factor Simulations...... 99

LIST OF TABLES

Table ...... Page

2.1 Overview of Basic Requirements for Each Phase ...... 7

2.2 Table of Various Frequency and Wavelengths ...... 12

3.1 Comparison of Baseline Board HFSS Simulations vs. VNA Measurements ...... 18

4.1 Comparison of Prototype Board HFSS Simulations vs. VNA Measurements ...... 23

4.2 Range Test Results for Prototype F-Antenna ...... 27

4.3 LQI Measurements for the FA Prototype Board at a Distance of 3 Meters ...... 28

5.1 Antenna Parameters Affected by Ground Plane Size ...... 34

5.2 Bandwidth Information for Various Stacked Prototype FAs ...... 36

Appendix Table

B.1 LQI Measurements for the FA Prototype Board at a Distance of 3.048 Meters ...... 75

B.2 LQI Measurements for the FA Prototype Board at a Distance of 6.096 Meters ...... 76

B.3 LQI Measurements for the MFA Prototype Board at a Distance of 3.048 Meters ... 77

B.4 LQI Measurements for the MFA Prototype Board at a Distance of 6.096 Meters ... 78 vi

vii

LIST OF FIGURES

Figure ...... Page

1.1 Standard HVAC System without Control Electronics ...... 3

2.1 Top Level Functional Design Decomposition ...... 10

2.2 Standard HVAC Control Board Enclosure ...... 12

3.1 Inverted F-Antenna Baseline Test Board ...... 16

3.2 Inverted F-Antenna HFSS Simulation View from Top ...... 16

3.3 (Left) Network Analyzer Used in Measurements (Right) S11 Test Setup ...... 17

3.4 Baseline Plot of Meandering F-Antenna S11 Parameter Comparison...... 19

3.5 Baseline Plot of Inverted F-Antenna S11 Parameter Comparison ...... 19

4.1 Prototype Boards ...... 20

4.2 Prototype F-Antenna HFSS 3D Model ...... 21 vii

4.3 Prototype Plot of F-Antenna S11 Parameter Comparison ...... 24

4.4 Prototype Plot of Meandering F-Antenna S11 Parameter Comparison ...... 24

4.5 Prototype Plot of Inverted F-Antenna S11 Parameter Comparison ...... 25

4.6 3D Radiation Pattern for a Prototype FA ...... 25

5.1 F-Antenna Equivalent Circuit Model...... 30

5.2 Prototype FA with a 0.2*λ Ground Plane Size ...... 32

5.3 Prototype FA with a 0.7*λ Ground Plane Size ...... 32

5.4 Prototype FA with a 1.2*λ Ground Plane Size ...... 33

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Figure ...... Page

5.5 S11 Plots of Various Stacked Prototype FAs with 1.0*λ Ground Plane Size ...... 35

5.6 Copied FA Array with 0.6*λ Between Antennas ...... 37

5.7 3D Radiation Pattern of 2x1 Copied FA Array with 0.2*λ Between Antennas ...... 38

5.8 3D Radiation Pattern of 2x1 Copied FA Array with 0.6*λ Between Antennas ...... 38

5.9 3D Radiation Pattern of 2x1 Copied FA Array with 1.0*λ Between Antennas ...... 39

5.10 Reflected FA Array with 0.6*λ Between Antennas ...... 40

5.11 3D Radiation Pattern of 2x1 Reflected FA Array with 0.2*λ Between Antennas .. 40

5.12 3D Radiation Pattern of 2x1 Reflected FA Array with 0.6*λ Between Antennas .. 41

5.13 3D Radiation Pattern of 2x1 Reflected FA Array with 1.0*λ Between Antennas .. 41

6.1 S11 Parameter for the Prototype FA with Encapsulation Material ...... 46

6.2 3D Radiation Pattern for a Prototype FA with Encapsulation Material ...... 47

6.3 S11 Parameter of a Prototype FA with Encapsulation Material and Water Layer .... 48

6.4 3D Radiation Pattern of a Prototype FA with Encapsulation Material and Water .... 49

6.5 Prototype FA in XZ Orientation Centered on the Connector Cavity...... 51

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6.6 S11 Parameter of FA in XZ Orientation with Motor Enclosure ...... 51

6.7 3D Radiation Pattern of Prototype FA in XZ Orientation with Motor Enclosure ..... 52

6.8 Prototype FA in XY Orientation at Control Board Height ...... 53

6.9 S11 Parameter of Prototype FA in XY Orientation at Control Board Height ...... 54

6.10 3D Radiation Pattern of Prototype FA in XY Orientation at Control Board Height...... 54

6.11 Reflected FA Array with Control Board Enclosure ...... 56

6.12 S11 Parameter of Reflected FA Array with Control Board Enclosure ...... 56

6.13 3D Radiation Pattern of Reflected FA Array with Control Board Enclosure...... 57

Figure ...... Page

6.14 Prototype FA in XY Orientation at Control Board Height ...... 58

6.15 S11 Parameter of a Prototype FA at Control Board Height with Control Board Enclosure and Connector ...... 59

6.16 3D Radiation Pattern of a Prototype FA at Control Board Height with the Control Board Enclosure and Connector ...... 59

6.17 Prototype FA Simulation in Ideal Orientation with All Environmental Effects ...... 61

6.18 S11 Parameter of FA in Ideal Orientation with All Environmental Factors ...... 61

6.19 3D Radiation Pattern for Prototype FA in Ideal Orientation with All Environmental Factors ...... 62

Appendix Figure

A.1 Top Level Functional Design Decomposition ...... 70

A.2 Design Decomposition of FR11 ...... 71

A.3 Design Decomposition of FR12 ...... 72

A.4 Design Decomposition of FR13 ...... 73

A.5 Design Decomposition of FR14 ...... 74

A.6 Design Decomposition of FR15 ...... 74

C.1 Prototype FA with a 0.2*λ Ground Plane Size ...... 80

C.2 Prototype FA with a 0.3*λ Ground Plane Size ...... 80

C.3 Prototype FA with a 0.4*λ Ground Plane Size ...... 81

C.4 Prototype FA with a 0.6*λ Ground Plane Size ...... 81

C.5 Prototype FA with a 0.8*λ Ground Plane Size ...... 82

C.6 Prototype FA with a 1.0*λ Ground Plane Size ...... 82

C.7 Prototype FA with a 1.0*λ Ground Plane Size ...... 83

C.8 S11 Plots of Various Stacked Prototype FAs with 0.2*λ Ground Plane Size ...... 83

Appendix Figure ...... Page

C.9 S11 Plots of Various Stacked Prototype FAs with 0.8*λ Ground Plane Size ...... 84

C.10 S11 Plots of Various Stacked Prototype FAs with 1.0*λ Ground Plane Size ...... 84

C.11 3D Radiation Pattern of Single Layer Prototype FA with 0.2*λ Ground Plane ..... 85

C.12 3D Radiation Pattern of Single Layer Prototype FA with 1.0*λ Ground Plane ..... 85

C.13 Copied Prototype FA Array Orientation ...... 86

C.14 2x1 Copied Prototype FA Array with 0.2*λ Between Antennas ...... 86

C.15 2x1 Copied Prototype FA Array with 0.6*λ Between Antennas ...... 87

C.16 2x1 Copied Prototype FA Array with 1.0*λ Between Antennas ...... 87

C.17 2x1 Reflected Prototype FA Array Orientation ...... 88

C.18 2x1 Reflected Prototype FA Array with 0.2*λ Between Antennas ...... 88

C.19 2x1 Reflected Prototype FA Array with 0.6*λ Between Antennas ...... 89

C.20 2x1 Reflected Prototype FA Array with 1.0*λ Between Antennas ...... 89

D.1 S11 Parameter for Prototype FA with Encapsulation and Water Layers ...... 91

D.2 3D Radiation Pattern of Prototype FA with Encapsulation and Water Layers ...... 91

D.3 S11 Parameter for 2x1 Copied FA Array with Encapsulation and Water Layers .... 92

D.4 3D Radiation Pattern for 2x1 Copied FA Array with Encapsulation and Water Layers...... 92

D.5 S11 Parameter for 2x1 Reflected FA Array with Encapsulation and Water Layers...... 93

D.6 3D Radiation Pattern for 2x1 Reflected FA Array with Encapsulation and Water Layers...... 93

D.7 Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector ...... 94

D.8 S11 Parameter for Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector ...... 94

Appendix Figure ...... Page

D.9 3D Radiation Pattern for Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector ...... 95

D.10 Prototype FA in XY Orientation at Control Board Height with Control Board Enclosure and Polymer Connector ...... 95

D.11 S11 Parameter for Prototype FA in XY Orientation at Control Board Height with Control Board Enclosure and Polymer Connector ...... 96

D.12 3D Radiation Pattern for Prototype FA in XZ Orientation at Control Board Height with Control Board Enclosure and Polymer Connector ...... 96

D.13 Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector ...... 97

D.14 S11 Parameter for Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector ...... 97

D.15 3D Radiation Pattern for Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector ...... 98

D.16 S11 Parameter for Prototype FA in XZ Orientation with All Environmental Effects Considered ...... 99

D.17 3D Radiation Pattern for Prototype FA in XZ Orientation with All Environmental Factors Included ...... 100

D.18 S11 Parameter for Prototype FA in XY Orientation at Control Board Height

with All Environmental Factors Included ...... 100

D.19 3D Radiation Pattern of Prototype FA in XY Orientation at Control Board Height with All Environmental Effects Included ...... 101

D.20 S11 Parameter of Prototype FA in XY Orientation Centered on the Connector with All Environmental Factors Included ...... 101

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LIST OF ABBREVIATIONS

HVAC Heating, Ventilation, and Air Conditioning

UHF Ultra-High Frequency

PCB Printed Circuit Board

RFID Radio Frequency Identification

RF Radio Frequency

FR Functional Requirement

DP Design Parameter

IFA Inverted F-Antenna

MFA Meandering F-Antenna

FA F-Antenna

VNA Vector Network Analyzer

BW Bandwidth

LQI Link Quality Indicator

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xiii

ABSTRACT

Straub, Arik L. M.S.E., Purdue University, August 2013. Optimized UHF Antenna Design, Simulation, and Implementation Applied to Residential HVAC Motors. Major Professors: Abdullah Eroglu and Carlos Pomalaza-Ráez.

There is relentless rising demand for wireless communication and radio frequency hardware in daily life. Applications of everyday wireless communication include: cell phones, smart devices/tablets, radio frequency identification (RFID) tags, medical device location networks, wireless remote electronics, home networks, internet capable home appliances and home electronics. Each application requires a variety of radio frequency hardware to successfully communicate wirelessly. A new and interesting application of wireless communication is implementing a heating, ventilation and air conditioning

(HVAC) system with wireless capabilities. The uses for such a HVAC system include: a wireless sensor network (WSN) that can facilitate energy savings operation modes and system status updates, system maintenance requests and updates, remote control of the

xiii system, and over the air firmware updates.

In this research, a standard HVAC blower motor is provided wireless communications features. Specific challenges of implementing this type of HVAC motor are considered. A standard printed control board (PCB) ultra-high frequency (UHF) F- antenna (FA) is taken and optimized for total gain, and bandwidth. After optimization,

xiv the antennas were built and tested using a vector network analyzer (VNA). The test results were then compared to the simulation results to for verification. Once the simulation results were verified, a new series of simulations were built to test varying environmental effects on the antenna such as the ones from: the PCB board enclosure material, the PCB enclosure material with a thin layer of water, placing the antenna inside the motor control board enclosure, the motor control board enclosure with power and signal connectors, and the orientation within the motor control board enclosure. This research shows the feasibility of implementing a PCB UHF FA to create a wireless

HVAC motor, and the effectiveness of the simulation procedures used.

xiv

PUBLICATIONS

Straub, A.; Eroglu, A.; Pomalaza- Ráez, C.; Becerra, R. “UHF Antenna Simulation,

Implementation, and Measurements for HVAC Systems,” in Fourth Nordic

Workshop on System and Network Optimization for Wireless (SNOW ‘13), 2-5

April, 2013.

Straub, A.; Eroglu, A.; Pomalaza- Ráez, C.; Becerra, R. “Optimized UHF Antenna

Design, Simulation, Implementation Methods of HVAC Systems,” in Topical

Conference on Antennas and Propagation in Wireless Communications.(IEEE

APWC ’13) 9-13 September 2013.

1. INTRODUCTION

1.1 Objective of Study

The objective of this research was to design a novel printed circuit board (PCB) antenna that can be implemented in a heating, ventilation, and air conditioning (HVAC) blower motor to facilitate wireless capabilities. Once an ideal antenna has been designed and optimized, the environmental factors and challenges inherent with an HVAC system were taken into account. The final antenna is optimized for the environmental factors, reduced cost of implementation, and overall performance. All antennas are designed and simulated using a 3-D electromagnetic simulator called Ansoft High Frequency Structure

Simulator (HFSS).

1.2 Standard HVAC System

HVAC systems are defined as “a mechanical system designed to satisfy the environmental conditions within an air conditioned space usually including temperature, relative humidity, distribution and movement of air, and air cleanliness” [1]. HVAC systems consist of at least four separate subsystems: the control and interface subsystem, the air transport subsystem, the air treatment subsystem, and the air flow subsystem.

Figure 1.1 shows the air treatment subsystem, the air flow subsystem, and part of the air

2 transport subsystem. There are currently no wireless components or sensors used in standard residential HVAC systems.

While there are no standard wireless components, there are certain aftermarket thermostats that have wireless communication capabilities. Wireless thermostats do not realize all potential benefits of implementing wireless communication within an HVAC system. For instance, communication wires could be removed or a set of wireless sensors could be implemented. A home HVAC WSN could provide information to the user on status of the system, energy use of the system, potential maintenance problems within the system, and a variety of other information. Research shows that implementing a WSN to monitor and control HVAC systems can result in overall energy savings [2] [3] [4], and there was also a patent application for a “RF interconnected HVAC system and security system” [5]. Other research including HVAC systems is primarily focused on modeling the RF signal propagation in an HVAC duct [6] [7] This research differs from other works in that it is specifically tailored toward creating a wirelessly capable blower motor, and includes simulation, implementation, and measurements of said motor and antenna.

Fig. 1.1 Standard HVAC System without Control Electronics

1.3 Wireless Communication

The first major breakthrough in wireless communication dated back as far as 1894 when Guglielmo Marconi invented a spark transmitter and later received a Nobel Prize in

1909 for his contributions to wireless radio. Ideas such as the smart home concept [8] [9], the internet things [10], cell phone communication, remote control, and smart device technology have made wireless communication ubiquitous in everyday life. Most home appliances and expensive consumer products include some type of wireless

4 communication. This communication may vary from including remote control, connecting to the internet for numerous reasons, or wireless data communication.

There are various protocols and techniques of communicating wirelessly which span a large number of frequencies. The research described in this thesis is primarily focused on implementing an UHF PCB antenna on an HVAC motor. Section 2 will break down the functional requirements of the system and will help to explain why the

UHF band was selected, and also why a PCB antenna was selected.

1.4 Overview of Thesis

The following chapters are designed to explain why specific design decisions were made, and to enumerate the research done. In Chapter 2, a System Engineering

Case Study for a wireless residential HVAC motor is presented. It is important because it presents a definition of the problem being approached, functional design decomposition, design constraints, and the resulting design decisions that shaped the research.

Chapter 3 discusses the simulations and process of verifying the simulations

created in HFSS. Two test boards are obtained and a set of simulations were created with a series of simplifications. Each simplification is reviewed and explained, and the final results are shown to verify the simulation models. Once the models were proven, a series of prototypes were created, simulated, and tested and the results are presented in Chapter

4. The results include range and LQI tests, and a comparison of the VNA measurements with simulated results.

Chapter 5 discusses three types of ideal optimizations that can be applied to the design of a UHF PCB antenna. The optimizations include finding the best ground plane

5 size, implementing a stacked antenna, and finding the best 2x1 array to implement. A variety of simulations will be done, and from these simulations a set of recommendations will be created. These recommendations will then be tested for environmental effects in

Chapter 6 to verify their validity for use with a residential HVAC system.

Once an ideal antenna design has been created, Chapter 6 will proceed to test this design and others against the effects likely to be seen within an HVAC system. These environmental effects will include the addition of an encapsulation material and thin layer of water, and simulations which include the control board enclosure. Overall, the simulations will point out weaknesses of the ideal antenna design from Chapter 5, and a new set of recommendations will be created. Finally, Chapter 7 will overview the goals and conclusions of the thesis.

2. SYSTEM ENGINEERING CASE STUDY

Section 2 has a brief System Engineering case study of creating a residential

HVAC motor with wireless capabilities. The case study will combine strengths of

Blanchard’s System Engineering Life Cycle [11] and strengths of Suh’s Axiomatic

Design decomposition process [12]. It begins by providing a detailed problem definition, and then proceeds to decompose the Functional Requirements (FRs) of the HVAC system.

The design decomposition process provides a series of FRs paired with possible solutions, known as Design Parameters (DPs). Once a basic functional decomposition is provided, the constraints and design decisions that are a result of the decomposition are provided.

2.1 Problem Definition

HVAC systems currently communicate through wired communication. An

overview of common communications is: downloading motor firmware, motor operation data communication, and motor command communication. A new series of HVAC thermostats are beginning to communicate using both wired communication and wireless communication. It is likely that other HVAC system components will follow the wireless communication trend. As such, a case study to create a residential HVAC motor capable of wireless communication. The implementation will likely come in phases, with each successive phase adding certain capabilities. The phases will include, but might not be

7 limited to: downloading firmware to a motor wirelessly, communicating data wirelessly, and communicating commands wirelessly.

After reviewing each phase in depth, one possible comprehensive problem statement was created: (1) improve and simplify the programming process by creating a wireless programmable motor, and choose a wireless communication technique such that a variety of secondary functions can be added at a later date; (2) improve the current maintenance model by adding a home owner “Check HVAC System” warning, and add the capability to wirelessly download motor information, motor operating data, and motor faults; (3) allow the residential HVAC motor to receive wireless commands from the system controller. Table 2.1 shows a brief overview of details for each phase.

Table 2.1 Overview of Basic Requirements for Each Phase

Phase 1: Phase 2: Phase 3: Download firmware Communicate motor Control the motor wirelessly data wirelessly wirelessly Environment Production environment Consumer’s home Consumer’s home

7 Motor location Mounted in HVAC Mounted in HVAC during Conveyor belt enclosure enclosure communication Motor information/status, Data available All motor data faults, and maintenance None data Data access type Read/write Read only None Command No No Yes capability?

Desired range 15 meters 3 meters 3 meters

Intended user Production line Maintenance technician Home consumer

External System controller, or Programming device Diagnostic device interfaces user interface

2.2 Functional Design Decomposition

Downloading the firmware to an HVAC motor normally happens in a production environment. A production environment consists of an open warehouse with a high number of HVAC motors in a small space. The warehouse may include manufacturing equipment, conveyer belts, or other such equipment. This function requires five major functions: the motor must store the motor firmware and memory map, the motor firmware must accessible and programmable, the motor must be programmable by a few specific devices, the communication protocol used must be housed in some type of hardware, and motor hardware must be able to communicate RF signals. Each of these functions are then broken down further to specify what devices can be used to program the motor, what hardware will be required to transmit and receive radio frequency signals, and what protocol is required to encode/decode the radio frequency signals to an understandable programming command.

The phase two function is to communicate data wirelessly to the home owner or a maintenance technician. This phase functionality will take place in a consumer’s home,

and require wireless communication to the system controller or a maintenance technician’s diagnostic device. Ideally, when any motor faults, maintenance issues, or non-ideal motor operations occur the motor will update the system controller, which will in turn notify the home owner. This will allow for improved home maintenance on minor tasks, and faster notification of a maintenance technician for larger tasks. When the maintenance technician is to maintain the HVAC system, he should be able to wirelessly connect and download the motor operating information, motor faults, maintenance issues,

9 or non-ideal motor operations information. This will give him useful information in seeing whether the fault lies with the motor, or elsewhere in the system.

The phase three function is for the motor to receive wireless control commands.

This functionality will be utilized in the user’s home, and will get rid of unneeded control wiring. The motor only needs to communicate to the system controller, which is normally a short distance away from the motor. Wireless control of the motor is only useful in that it reduces the amount of internal wiring required for the HVAC system. A short overview of the environment, the range required, the data needed, and the type of access to the data required is provided in Table 2.1.

Phase two and three requires three of the same functional requirements as phase one: the motor must communicate to desired devices, the communication protocol used must be housed in some type of hardware, and motor hardware must be able to communicate RF signals. This means that the wireless communication protocol used in phase one must be able to accommodate the needs of phases two and three, or else separate wireless communication protocols must be implemented at each phase.

Implementing two separate communication problem could prove expensive and much more complex system. At this time it is possible to make a decision that the implementation of the three wireless phases will be implemented using a single wireless communication protocol.

The final two functions, be able to program the motor (wired) and work in a standard HVAC system, are both being implemented already. These functions are responsible for the functionality of current HVAC motors, and as such they have not been decomposed in great detail. Figure 2.1 shows the top-level functional design

10 decomposition, and Equation 2.1 verifies the Independence Axiom [12] and shows that the design is partially coupled. By approaching the design in this manner, a path dependent design can be created. For instance, must be designed and implemented before and are designed. If this path dependence is not followed, then implementing and may cause issues which block from being achieved correctly. For further decompositions and tables verifying the independence axiom, check Appendix A.

(2.1)

{ } [ ] { }

Fig. 2.1 Top Level Functional Design Decomposition

2.3 Design Constraints

Now that there is an initial functional decomposition with path dependency understood, it allows for constraints to be introduced. Based on these constraints, design parameters may be changed or selected to meet them. The constraints considered at this time are: space constraints within the system, cost constraints of implementing the product, complexity of the system to reduce time to market. There are many more constraints, but this is just a brief case study and only a few basic constraints will be considered.

2.3.1 Size constraint

The first constraint is meeting the size constraints within the system. Any system that will be implemented within a residential HVAC motor must first fit within the space allowed by the system. Most residential HVAC blower motors have a cylindrical control board enclosure with a diameter of 125 mm, and a vertical space of about 51 mm.

Most antennas come in sizes of a quarter or half the wavelength. This means that

as the desired communication frequency is increased, the size of the antenna is decreased.

As such, there is a minimum frequency antenna that can fit into the control board enclosure. There are techniques to minimize the size of these antennas, but for simplification reasons these will be ignored. Figure 2.2 shows a standard control board enclosure for residential HVAC motors. The enclosure is shown in an HFSS simulation, and it does not include the power or signal connectors. Table 2.2 shows a few frequencies and their corresponding wavelengths.

Fig. 2.2 Standard HVAC Control Board Enclosure

Table 2.2 Table of Various Frequency and Wavelengths

Wavelength Half Wavelength Quarter Wavelength 12 Frequency (GHz) (m) (m) (m)

0.5 0.6 0.3 0.15

1 0.3 0.15 0.075

2 .15 0.075 0.0375

3 0.1 0.05 0.0025

2.3.2 Minimize cost of product

The second constraint is to minimize the cost of implementing the hardware required for wireless capabilities. For most businesses this is a complex balancing act of introducing new features that the customer is willing to pay for, and maximizing the profit of the company. Two possible ways to reduce cost are discusses further in this section. The first is to use a standard communication protocol that is already widely accepted. Although buying hardware with the communication protocol already installed is more expensive, it is much cheaper to implement this hardware than to try creating a new communication protocol.

Another way to reduce the cost is to select and implement the correct type of antenna. There are many different types of PCB antennas that can be implemented cheaply. For example, a simple patch antenna can be very easy to design, match, and implement. Another example is a variation of an F-antenna, which can be designed to reduce implementation size and reduce the need for a matching network.

2.4 Design Decisions

Due to the constraints from above a few design decisions were made early on.

The first decision was to operate at 2.4 GHz. The reasoning behind this was three-fold:

2.4 GHz is in an ISM band which does not require a license to operate in, the 2.4 GHz

ISM band houses a large number of accepted communication protocols, and a 2.4 GHz antenna is very small. The second design decision was to use a PCB antenna. This will reduce the hardware cost to implement. These two decisions shaped the next section of the paper, which will review designing and optimizing an ideal UHF PCB antenna.

3. ANTENNA SIMULATION AND VERIFICATION USING HFSS

In this thesis, a series of simple test boards were developed to verify the HFSS

simulation techniques used. Two specific variations of a UHF PCB F-Antenna board

were used for testing, a Meandering F-Antenna (MFA) and an Inverted F-Antenna (IFA).

The HFSS simulation verification stage is required to verify that the simplifications made

were valid and would not cause future problems. All simplifications were made to either

make HFSS simulations easier to implement, or to reduce the overall simulation run time.

These simulations are referred to as baseline simulations in future sections.

A picture of the IFA antenna can be seen in Figure 3.1, and a picture of the MFA

prototype is shown in Figure 4.1. The IFA is a modified version of a standard F-Antenna

that can be matched to 50 ohms without a matching network, under ideal conditions. The

MFA is also a modified version of a standard F-antenna, but it is optimized for a small 14

form factor. The PCB antenna track of a MFA meanders at right angles to achieve the

quarter wave length required in a smaller footprint. In Chapter 4, a standard F-Antenna is

introduced for comparison. The standard F-Antenna is shown in Figure 4.1 and

resembles a capitol “F” which is why these antennas are known as F-Antennas.

3.1 Simulation Simplifications and Excitations

A series of baseline simulations were generated. The simplifications made will be described in this section. The first simplification in the baseline simulations was to replace all diagonal lines with a series of squares to simplify building the structure in

HFSS. The only exception to this simplification is on the antenna itself. While making minor changes to the ground plane edges should have little effect on the simulations, changing the dimensions and orientation of the antenna would have had a higher impact on simulations.

The second simplification in the simulations was to severely reduce the number of vias between the ground planes. There were around 160 vias connecting the top and bottom ground plane of the test boards. In RF PCB layouts, a high number of vias connecting the top and bottom ground planes are used for a variety of reasons. Two specific reasons include: adding vias near ground pins minimizes parasitic inductance between the ground plane and any nearby ground pins, and having a large number of vias

between top and bottom ground metallization helps to create good RF grounds. Vias are 15

used to make electrical connections between layers of board on PCBs. Essentially, it is a plated hole that connects the pad of one PCB layer to a collocated pad of a different PCB layer. Creating a large number of vias in the simulations would have significantly increased the simulation run time. As such, a few different simulations were run with a varying numbers of vias to check how the vias would affect the simulations. Three different simulations were run with 14 vias, 21 vias, and 42 vias. The simulations results

16 were almost identical, so we chose to use 21 vias in the baseline simulations. Figure 3.1 shows a test board and Figure 3.2 shows the simulation 3D rendering for comparison.

Fig. 3.1 Inverted F-Antenna Baseline Test Board

Fig. 3.2 Inverted F-Antenna HFSS Simulation View from Top

The final simplification in the baseline simulations was to ignore matching networks and transmission feed lines, and to use lumped wave ports to excite the antennas. Using lumped wave ports as an excitation for the antennas allowed a complex

17 impedance to be input for the excitation. At this point, if 50 Ω is selected as the excitation impedance then we can assume that the excitation is perfectly matched to the

50 Ω F-Antennas under simulation.

Fig. 3.3 (Left) Network Analyzer Used in Measurements (Right) S11 Test Setup

3.2 Test Board VNA Measurements and HFSS Simulation Results Comparison

The MFA test board and the IFA test board were used for verification testing.

They were attached to a vector network analyzer (VNA) to test the S11 parameter. Each

VNA measurement was compared to the HFSS results on three parameters: the center frequency location, the magnitude of the center frequency, and the bandwidth of the reflection coefficient (S11). Table 3.1 shows the results in tabular form, while Figure 3.3 and Figure 3.4 show the results in graphical form. The results in table one show that while there is a difference in the magnitude of the S11 parameter, the values for the center frequency and the bandwidth (BW) are fairly close. At worst, the results for the center frequency are only 10.78% shifted off the measured values, and the results for the

18 bandwidth were only 11.11% off. These simulations are accurate enough to show the trends of the antennas, and will serve the purpose of this study well. The errors could be attributed to a variety of factors including the simplifications described above, or even slight changes in the measurement setup process. Overall, this comparison proved that the simplifications made were acceptable.

Table 3.1 Comparison of Baseline Board HFSS Simulations vs. VNA Measurements

Antenna Type Inverted F-Antenna Meander F-Antenna

Data Type VNA HFSS VNA HFSS

S11 Magnitude (dB) -19.748 -11.485 -28.170 -26.870

S11 Magnitude Difference 8.263 dB 1.300 dB

Center Frequency (GHz) 2.325 2.385 2.505 2.235

Center Frequency Difference 2.58% 10.78%

Bandwidth (GHz) 0.360 0.405 0.165 .180

Fractional Bandwidth 0.155 0.170 0.066 0.081

Bandwidth Difference 11.11% 9.09%

Fig. 3.4 Baseline Plot of Meandering F-Antenna S11 Parameter Comparison

Fig. 3.5 Baseline Plot of Inverted F-Antenna S11 Parameter Comparison

4. ANTENNA PROTOTYPES AND TESTING

A series of prototype boards were designed and implemented within a residential

HVAC motor for proof of concept and feasibility testing. Several boards implementing variants of a small form factor UHF PCB FA were implemented. The three variants include: a standard F-Antenna (FA), an inverted F-Antenna (IFA), and a meandering F-

Antenna (MFA). Figure 4.1 shows the prototypes boards created and tested.

Fig. 4.1 Prototype Boards

4.1 Simulation Simplifications

The HFSS simulations follow all of the same simplifications described in Chapter

3.1 with a difference. While the baseline test boards only have an antenna and a single transmission line to route, the prototype boards have 31 different components with varying footprints and routing between the components. As such, it would take too long to include all of these factors in the simulations. The final simplification made for these simulations was to ignore all routing and footprints. The only area removed from the ground plane in prototype simulations was the foot print of the microcontroller. This was removed because the section was not directly linked to ground, and as such should be taken into account during simulations. Figure 4.2 shows the FA HFSS simulation file for comparison to the FA shown in Figure 4.1

Fig. 4.2 Prototype F-Antenna HFSS 3D Model

4.2 Comparison of Prototype VNA Measurements and HFSS Simulation Results

The three prototype boards had a standard SMA connector soldered onto the boards so that VNA measurements could be made. For reference, the DigiKey part number for the SMA connector is ARF1579CT-ND. This connector needed only minor modifications to be connected to the VNA successfully. The VNA measurements were compared to the HFSS results using three parameters: the center frequency location, the magnitude of the center frequency, and the bandwidth of the S11 parameter. Table 4.1 shows a tabular comparison of the three prototype boards, while Figures 4.3, 4.4, and 4.5 provide a graphical comparison.

The results from the prototype simulations were much closer to the VNA results.

Two outliers are shown: the S11 magnitude difference for the IFA where there is a 15.6 dB error and the BW measurements for the MFA where there is a 20% error. Despite these inconsistencies, the HFSS results match similarly as the results in Chapter 3. The

HFSS simulations also match the shape of the VNA measurements more closely. For

instance, in Figure 4.4 the simulation predicts the undesirable dip in the S11 parameter at 22

1.5GHz accurately. In Figure 4.5, the simulation also predicts the undesirable dip at around 1.3GHz. These points show that the HFSS simulations accurately predict the trends of the prototype VNA measurements.

Figure 4.6 shows the 3D radiation pattern of a Prototype F-Antenna from an

HFSS simulation. There were no radiation pattern measurements taken to compare to, but the result should be shown for completeness.

Table 4.1 Comparison of Prototype Board HFSS Simulations vs. VNA Measurements

Antenna Type FA MFA IFA

Data Type VNA HFSS VNA HFSS VNA HFSS

S11 Magnitude (dB) 28.063 33.290 -34.525 -28.134 34.335 18.734

S11 Magnitude Difference 5.227 dB 6.391 dB 15.601 dB

Center Frequency (GHz) 2.610 2.370 2.220 2.265 2.535 2.430

Center Frequency 9.195% 2.027% 4.142% Difference

Bandwidth 0.810 0.750 0.360 0.285 0.570 0.530

Fractional Bandwidth 0.310 0.316 0.225 0.222 0.126 0.162

Bandwidth Difference 7.407% 20.833% 5.263%

Fig. 4.3 Prototype Plot of F-Antenna S11 Parameter Comparison

Fig. 4.4 Prototype Plot of Meandering F-Antenna S11 Parameter Comparison

Fig. 4.5 Prototype Plot of Inverted F-Antenna S11 Parameter Comparison

Fig. 4.6 3D Radiation Pattern for a Prototype FA

4.3 LQI and Range Measurements

The second set of measurements included range measurements and Link Quality

Indicator measurements. A LQI measurement is the measurement of the received energy that occurs, and can be used to quantify the quality of the wireless channel. If the energy of the incoming signal is high, it means that the channel between the transmitter and receiver is a high quality channel. Range measurements are very simple measurements where a standard controller sent an “ON/OFF” command to the residential HVAC motor located inside the HVAC enclosure. If the motor responded correctly, by turning on or off, the test was considered a success.

A number of range tests were performed which changed four variables: one test modified the angle of HVAC enclosure which changes the signal transmission path, the second tests modified the height of the control board, the third set of tests modified whether the ventilation openings on the HVAC enclosure were open or closed, and the final set of tests tested the range when the HVAC access panel was installed, and when

the HVAC access panel door was removed. One issue occurred during range testing. 26

There was a limited space open for testing, and for many of the tests the communication range exceeded this limit. The maximum measurements will be starred in Table 4.2.

Table 4.2 Range Test Results for Prototype F-Antenna

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45°Right Board (m) (m) (m) (m) (m) (m) Height 0.61 m 19.202* 19.202* 19.202* 9.754 19.202* 19.202*

1.22 m 19.202* 19.202* 19.202* 6.706 19.202* 18.288

HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45°Right 45°Left 0° 45°Right Board (m) (m) (m) (m) (m) (m) Height 0.61 m 19.202* 19.202* 19.202* 7.516 8.458 8.534

1.22 m 19.202* 19.202* 19.202* 7.087 8.687 9.144

The second type of measurement taken was an LQI measurement. LQI stands for 27

“Link Quality Indicator” and it is a measure of the quality of the communication link.

The LQI value was obtained using a built in function of the MC13213 microcontroller used. Currently, there is no well-defined or widely accepted equation for LQI, and the user’s manual for the MC13213 does not specify an equation either [13]. The only information available for LQI is that the values vary from -30 dBm to -95 dBm, and that the LQI value is a measurement of energy received [13]. Table 4.3 shows a sample of the

LQI measurements taken. For the rest of the LQI measurements please see Appendix B.

Table 4.3 LQI Measurements for the FA Prototype Board at a Distance of 3 Meters

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -90.8 -72.5 -85.8 -90.45 -89.15 -82.65

1.22 m -87.95 -73.4 -72.6 -85 -87 -91.75

HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -69.4 -74.2 -71.05 -85.35 -93.7 -90.45

1.22 m -70.95 -75.15 -75.75 -82.25 -82.9 -

5. ANTENNA DESIGN AND OPTIMIZATIONS

After proof of concept and feasibility testing were finished, a series of antenna optimizations were slated for simulation. The output of this section was a novel UHF

PCB Antenna design that is optimized for the design constraints inherent in the system.

Overall, three modifications were simulated to create an optimized version of the original

F-Antenna design, and these modifications were designed to: increase the gain and change directionality, increase bandwidth, and improve total gain.

After initial simulations, it became apparent that the three variations of F-

Antennas behaved the similarly in HFSS simulations. Due to this finding, and to reduce the number of simulations, only the F-Antenna was extensively simulated after the ground plane variation simulations. In the next sections, a small subset of the simulations

will be shown. A more comprehensive presentation of simulation results is available in 29

Appendix C.

5.1 F-Antenna Theory

PCB F-Antennas can be described as a monopole antenna where the top microstrip of the antenna has been bent 90° to run parallel to the PCB’s ground [14].

Introducing the 90° turn serves two purposes in this design: first it minimizes the height/size of the antenna, and second it allows the microstrip to be printed directly on a

PCB. The turn also has negative side effects; it introduces a parasitic capacitance into the antenna input impedance that is formed by the open circuit created between the top microstrip and the ground plane. This parasitic capacitance can be counteracted by adding a short circuit stub into the antenna design. Thus, an F-Antenna is created with a single feed point and a short circuit to ground.

The placement of the feed line is very critical in the design of the antenna. The feed line location must achieve two tasks. First, it must be placed so that the parasitic capacitance formed by the open circuit is cancelled out by the inductance created with the short circuit. Second, it must be placed so that the resistive element of the impedance is at a desirable value, ideally 50 Ω. An equivalent antenna model for the circuit is shown in Figure 5.1 where: the inductor L1 is created by the short circuit stub to ground, the voltage source V1 is the feed point, the capacitance C1 is created by the open circuit to ground, and the resistance R1 is the real impedance created by the antenna.

Fig. 5.1 F-Antenna Equivalent Circuit Model

5.2 Ground Plane Size Variations

Ground plane size can significantly change the antenna performance and properties. Specifically, if the ground plane is too small it can greatly change the resonant frequency and the bandwidth of the antenna [15]. The relationship between the ground plane size and the gain parameter is very complex and will be reviewed below. In this thesis, ground plane size will be correlated directly to frequency wavelength (λ). The equation for frequency wavelength is shown in Equation 5.1 where: v is the speed of light, and f is and is equal to the frequency of signal transmission.

(5.1)

Figures 5.2, 5.3 and 5.4 show the 3D radiation pattern of a prototype FA with a

0.2*λ, 0.7*λ, and 1.2*λ ground plane size respectively. The following figures show how the 3D radiation pattern is steadily distorted as the size of the ground plane is increased.

Figure 5.2 shows a nice doughnut pattern, which is often seen for an ideal FA, but Figure

5.4 shows an omnidirectional pattern with various nulls and signal transmission lobes.

Although there is a negative effect to the gain pattern shape, there is a positive effect to 31

the maximum value of the gain parameter. The value of the gain pattern is steadily increased 2.24 dB in Figure 5.2 to 3.76 dB in Figure 5.4.

Fig. 5.2 Prototype FA with a 0.2*λ Ground Plane Size

Fig. 5.3 Prototype FA with a 0.7*λ Ground Plane Size

Fig. 5.4 Prototype FA with a 1.2*λ Ground Plane Size

Table 5.1 shows an overview of the other parameters that ground plane size effects. For the ground plane sizes shown, there was little effect on the location of the center frequency when compared to other parameters. Bandwidth is affected by the ground plane. Aside from the outlier at 0.3*λ, the bandwidths are increased when the

33 ground size is greater than 0.8*λ, which corresponds to the results in [15]. Table 5.1 also shows that the value of the center frequency varies from -16 dB to -35 dB, but these are all acceptable values. Overall, it can be concluded that the ground plane strongly affects the performance of the antenna in a complex way.

Table 5.1 Antenna Parameters Affected by Ground Plane Size

Center Ground Plane Center Relative Frequency Bandwidth Size Frequency Fractional Value (GHz) (% of λ) (GHz) Bandwidth (dB) 20 2.460 -16.577 0.540 0.219

30 2.370 -27.335 0.705 0.297

40 2.370 -24.125 0.540 0.228

50 2.325 -21.769 0.480 0.206

60 2.310 -30.449 0.510 0.220

70 2.280 -25.254 0.525 0.230

80 2.280 -23.971 0.645 0.283

90 2.295 -18.602 0.705 0.307

100 2.355 -21.828 0.690 0.293

110 2.370 -25.811 0.615 0.259

120 2.355 -35.461 0.570 0.242

5.3 Stacked Antenna Variations

A second set of simulations was setup to try to increase the bandwidth of the antenna without reducing the overall performance of the antenna. One way to do this is to create a copy of the FA and overlay it on another PCB layer. These layers then must have the feed point and short circuit stub connected together with a via. In essence, a second FA is “stacked” on top or bottom of the original FA. This technique is a variant of a technique used by Olmos to create a double-strip IFA [16].

Figure 5.5 shows the S11 parameter results when multiple antennas are stacked on top of one another. The graph shows the change in center frequency and bandwidth when multiple layers are added. The dark blue line shows the S11 parameter of prototype FA, while the next three lines show the S11 parameter when a stacked antenna layer is added iteratively. The final line is displayed to visualize where the bandwidth is calculated, at the -6 dB point. Overall, the center frequencies shifted to higher frequencies, while the bandwidth is increased by 0.14 GHz, or a total of about 24%.

Table 5.2 shows more information about the bandwidth increase, such as the exact bandwidth, the percent bandwidth increase when compared to a single layer antenna, and the relative fractional bandwidth. Of particular interest is that there were no negative effects to the 3D radiation shapes. Appendix C provides more simulation results for comparison.

Fig. 5.5 S11 Plots of Various Stacked Prototype FAs with 1.0*λ Ground Plane Size

Table 5.2 Bandwidth Information for Various Stacked Prototype FAs

Increase in Number of Bandwidth Relative Fractional Bandwidth Antenna Layers (GHz) Bandwidth (%) 1 0.555 0 0.242

2 0.670 24.32 0.293

3 0.675 21.62 0.288

4 0.670 24.32 0.295

5.4 Antenna Array Variations

A final set of simulations were run that test various antenna array setups with two orientations. First, a 2x1 array was created that would match the built in HFSS function.

Once the outputs between the user created array, and the built in function were matched, a new series of array modifications could be done. The initial simulations were designed to vary distances between the antennas, while keeping the same orientation of the

antennas. The distances used were: 0.2*λ, 0.6*λ, and 1.0*λ. To reduce the number of figures shown, the S11 parameters will not be shown. These parameters had only negligible changes made between the different array setups.

Figures 5.7 shows the orientation, which will be referred to as “Copied FA Array” where the antenna is copied along a single axis. The distance between the antennas shown in Figure 5.7 is 0.6*λ. Figures 5.8, 5.9, and 5.10 will show the 3D radiation patterns of a 2x1 copied FA array with the distance between antenna components varying.

It can be seen that the gain pattern is almost doubled for all three figures, but that the

37 shape of the radiation pattern is modified. This type of multiplication effect is correct as long as the array is designed carefully [17].

A simplified pattern multiplication equation for arrays of identical elements is shown in Equation 5.2. The array factor from Equation 5.2 is a function of the number of elements, the geometric arrangement including spacing and orientation of the elements, and the relative excitation magnitude and phase differences of the elements.

[ ] [ ( )] [ ] (5.2)

Fig. 5.6 Copied FA Array with 0.6*λ Between Antennas

Fig. 5.7 3D Radiation Pattern of 2x1 Copied FA Array with 0.2*λ Between Antennas

Fig. 5.8 3D Radiation Pattern of 2x1 Copied FA Array with 0.6*λ Between Antennas

Fig. 5.9 3D Radiation Pattern of 2x1 Copied FA Array with 1.0*λ Between Antennas

Another set of array simulations was created where the antenna reflected along the axis rather than copied along the x-axis, and these simulations will be referred to ask reflected FA arrays. These simulations were created to see what effect the orientation of

the antenna array elements would have on the 3D radiation pattern displayed. Figure 39

5.10 shows the orientation of a prototype FA array with a distance between the antennas of 0.2*λ.

Figures 5.11, 5.12, and 5.13 show the 3D radiation patterns of reflected FA arrays where the distance between array components is varied. It can be seen that the gain is no longer doubled, and that the gain patterns are changed due to the orientation change.

Overall, Figure 5.11 shows an almost omnidirectional gain pattern, while the next two are distorted similarly to Figure 5.8 and Figure 5.9.

Fig. 5.10 Reflected FA Array with 0.6*λ Between Antennas

Fig. 5.11 3D Radiation Pattern of 2x1 Reflected FA Array with 0.2*λ Between Antennas

Fig. 5.12 3D Radiation Pattern of 2x1 Reflected FA Array with 0.6*λ Between Antennas

Fig. 5.13 3D Radiation Pattern of 2x1 Reflected FA Array with 1.0*λ Between Antennas

5.5 Ideal Antenna Design Recommendations

Overall, three kinds of optimizations were covered in Chapter 5, and from each of these optimizations a few recommendations will be made. The first optimization included modifying the size of the ground plane, and a few interesting facts were concluded. First, having a ground plane of 0.2*λ yields no solid improvements, but increasing the size of the ground plane yields both positive and negative effects. These effects coupled with the size constraints mentioned in Chapter 2 mean that a ground size of 0.3*λ is recommended. This size ground plane yields unusually high bandwidth coupled with a 3D radiation pattern that has not yet been significantly distorted, and a small ground plane is ideal for implementation with in a standard HVAC system.

The second type of optimization discussed is the implementation of a stacked antenna to improve bandwidth of the antenna. While a variety of different layers and layer placements were simulated, no significant gain was seen after adding a single additional layer. If the additional layer is added on the bottom layer of the PCB two

benefits will be seen: firstly the additional bandwidth will be added and a slight shift in 42

center frequency will be applied, and secondly the extra antenna layer will guarantee that no ground plane is accidently placed underneath the antenna. Also, if the layer is implemented on the bottom layer of the PCB, no additional cost should be added.

The third type of optimization discussed is the implementation of an array of FAs.

This optimization seemed most likely to increase the range and overall performance of the antenna, but Chapter 6 will discuss why this is not the case. For an ideal implementation, a reflected FA array is implemented in an ideal situation with little to no

43 metal surrounding it. The reflected array achieves a significant increase in gain and an almost omnidirectional pattern. For the application within an HVAC system, a copied

FA array with a distance of minimum separating distance is recommended for a variety of reasons. The copied FA array achieves a semi-directional gain pattern and a doubling of the total gain while being implemented on the smallest form factor under simulation.

Overall, a two layer stacked FA antenna with a 0.3*λ ground plane size implemented in a reflected 2x1 array is the ideal antenna design. This optimized antenna will combine all of the most favorable aspects of each optimization, and these will work together to create a novel FA design. The novel optimized antenna described above does not currently take into account any environmental effects, but it does take into account certain size constraints mentioned in Chapter 2. The environmental effects will be considered in the Chapter 6.

6. HVAC ENVIRONMENTAL EFFECTS

This section discusses the negative effects of a variety of environmental effects.

These effects include: the presence of an encapsulation material, and presence of a control board enclosure. The presence of an encapsulation material will negatively affect antenna performance, and HFSS simulations can be used to gage and correct for such effects. The antennas have not been modified to correct the negative effects at this time, but potential corrections may be suggested from the simulations. The control board enclosure will also have negative effects on antenna performance. Mainly, the location and orientation of the antenna board relative to the location of the polymer connector will affect how the RF signal propagates out of the enclosure.

6.1 Encapsulation Material

A special insulation material is often used to protect electrical circuits from the surrounding environment. The material may be used to: protect the circuit from water damage, insulate the circuit to ensure proper functionality, dissipate heat, retard open flame damage, or protect against drop or shock damage to the circuit. This type of material has many methods of application and as such may be called an encapsulation material, a dipping material, a casting material, or a potting material. In this thesis, the material will be referred to as an encapsulation material.

Adding an encapsulation layer to the simulations changed the antenna impedance and to shifted the antennas resonant frequency. These effects have been verified in two case studies: one involving placing a UHF RFID antenna for tracking wood logs, and another for using a UHF tag to track seals at sea [18] [19]. In these papers, the antennas are re-tuned by changing the size of various components of the F-Antenna. For example, in the seal tracking paper, the dimensions of the antenna was reduced by twenty percent to retune the antenna [19]. The negative effects of the encapsulation material will be linked to the dielectric characteristics of the encapsulation material. In our simulations the dielectric constant of the encapsulation material was assumed to be 3.6. This value was used in simulations because it was the given dielectric value of a sample encapsulation material obtained.

A secondary set of simulations was created to add another factor into account.

Encapsulation materials are often used to protect a circuit from water/moisture damage.

Due to this reason, and the fact that some HVAC systems are used to remove moisture from the air, it is prudent to add simulations that take such water content into account. A

thin homogenous layer of fresh water was added to encapsulation material simulations.

6.1.1 Encapsulation material simulations

Figure 6.1 shows the new center frequency of a prototype FA with the encapsulation material added. The resonant frequency shift is apparent in all simulations.

A secondary center frequency is also apparent around 2 GHz, which is not ideal. The

S11 value at the center frequency is -17.96 dB, and the value of the secondary center frequency is -10.88 dB. The narrow bandwidth of the first band is around 33.5 MHz and

46 the wider bandwidth of the second band is 65 MHz. The bandwidth of the 2.5 GHz ISM band is around 83.5 MHz, which means that only the wider band contains close to adequate bandwidth if the antenna were retuned. These separate bands could be combined, or the narrowband could be filtered out by selecting a correct matching network. Figure 6.2 shows the corresponding 3D radiation boundary of the prototype FA.

When the 3D radiation boundary in Figure 6.2 is compared to Figure 4.6, it is found that virtually no change in the radiation boundary is achieved. A detailed list of all environmental effect simulations can be found in Appendix D.

Fig. 6.1 S11 Parameter for the Prototype FA with Encapsulation Material

Fig. 6.2 3D Radiation Pattern for a Prototype FA with Encapsulation Material

6.1.2 Encapsulation material with water simulations

Figure 6.2 shows the S11 parameter of a prototype FA with the encapsulation

material and a thin layer of water, and Figure 6.4 shows the corresponding 3D radiation 47

boundary. If Figure 6.3 is compared to Figure 6.1, it can be noted that there is a slight shift of the center frequency and a shift in the impedance of the antenna again. The shift of the antenna impedance is apparent when the values of the S11 parameters at the center frequencies are compared. A lower value S11 parameter at the center frequency signifies a good match between the excitation and the antenna. Figure 6.4 shows that when a thin layer of water is added, the directionality of the total gain is changed. For instance in

Figure 6.2, a regular doughnut shape radiation pattern is achieved, but Figure 6.4 is

48 different. The radiation in the –Z direction has been reduced, and that reduction corresponds to an increase of radiation in the +Z direction.

Fig. 6.3 S11 Parameter of a Prototype FA with Encapsulation Material and Water Layer

Fig. 6.4 3D Radiation Pattern of a Prototype FA with Encapsulation Material and Water

6.2 Control Board Enclosure

The enclosure where the antenna board is located affects how the antenna radiates

49 to a large degree. Figure 2.2 shows a standard control board enclosure. This enclosure is bolted onto the end of a residential HVAC motor, and it has a void where a polymer connector is located. To simplify simulations, an aluminum plate was assumed to be placed between the control board enclosure and the HVAC motor. The aluminum plate can be assumed as a valid simplification because all electromagnetic signals and interference of the motor occur at much lower frequencies, which should not affect the antenna propagation. The aluminum plate also simplifies the simulations, and it isolates the effects of the enclosure on the antenna so only these effects are shown.

The enclosure is an aluminum encasement with a small window opening for the polymer connector. This polymer connector allows power and signal connectors to be included. Due to the single opening and the directionality of the antennas, it became apparent that the orientation and placement of the antenna is very important. For this reason, each antenna simulated at this point was simulated with three different orientations: in the XY plane (horizontal) at the control board height, in the XY plane

(horizontal) centered on the polymer connector, and in the XZ plane (vertical) centered on the connector. The first set of simulations shown does not include the connectors, and leave a cavity where the connector should be. A second set of simulations were added to include a polymer block in place of the connectors. The nylon block does not include pins for the connectors.

6.2.1 Control board enclosure simulations

Figures 6.5, 6.6 and 6.7 show the ZX orientation, the S11 parameter, and the 3D radiation pattern of a prototype FA. It can be seen that this is the ideal placement and

orientation of the antenna because it maximizes the gain of the antenna, and minimizes the changes of antenna impedance. The 3D gain of a standard FA is a doughnut shape with the antenna radiating in the X and Z directions, as shown in Figure 4.6. The antenna gain is maximized by placing the antenna so that it radiates directly through the connector cavity. The effects of changing the antenna impedance are also minimized because there is no aluminum plate parallel to the antenna or antenna ground plane. Figure 6.6 shows that the antenna is slightly detuned, but the matching between the antenna and excitation are maintained. Figure 6.6 also shows that bandwidth has been increased to 270 MHz.

Fig. 6.5 Prototype FA in XZ Orientation Centered on the Connector Cavity

Fig. 6.6 S11 Parameter of FA in XZ Orientation with Motor Enclosure

Fig. 6.7 3D Radiation Pattern of Prototype FA in XZ Orientation with Motor Enclosure

Figures 6.8, 6.9 and 6.10 show the same results for a Prototype FA in XY orientation situated at the height of a standard HVAC control board. The height of a standard control board falls below the lip of the connector opening, and it is fairly close

to the aluminum bottom of the control board enclosure. Orienting the antenna so that the 52

null in the standard radiation pattern is directly in line with the connector hole will reduce antenna signal propagation, and thus reduce the strength of the total gain. Any RF signals that propagate out of the enclosure must first reflect around the inside of the enclosure, thus wasting power and interfering with other RF signals.

Being directly above the aluminum enclosure creates parasitic capacitances and parasitic inductances between the antenna board and the enclosure. These parasitic components will change the impedance of the antenna, and the parasitic components will

53 also change with the frequency. Figure 6.9 shows that the matching between the antenna and the excitation is not as good as in Figure 6.6. The absolute best center frequency in

Figure 6.9 is -7.06 dB, when the best center frequency of Figure 6.5 is -23.52. The center frequency is also shifted differently; a shift up to 3.76 GHz compared to a shift down to

2.2 GHz

Fig. 6.8 Prototype FA in XY Orientation at Control Board Height

Fig. 6.9 S11 Parameter of Prototype FA in XY Orientation at Control Board Height

Fig. 6.10 3D Radiation Pattern of Prototype FA in XY Orientation at Control Board Height

At this point, it is prudent to show the array simulations with a setup similar to

Figures 6.8, 6.9, and 6.10. The following simulations are of prototype FA arrays where the antenna was reflected along the x-axis, and the motor enclosure was added to view the effects. Array simulations were shown to significantly increase the total gain in

Chapter 5. For this reason, array simulations were continued alongside standard FA simulations.

When comparing Figure 6.9 to Figure 6.12, it shows that both S11 parameters have been significantly detuned and the antenna impedance has been changed, thus resulting in the antenna being less matched to the excitation. Although the antenna is less matched to the excitation, it still creates a S11 value of -13.29 dB, which is below the -6 dB point required for good signal transmission. When the 3D radiation patterns of Figure

6.13 and Figure 6.10 are compared, it becomes apparent that a lot of power is lost somewhere in the array simulations. Due to this loss of gain and the more difficult implementation of an array of antennas, it was decided that the focus of the thesis would remain mainly on non-array simulations.

Fig. 6.11 Reflected FA Array with Control Board Enclosure

Fig. 6.12 S11 Parameter of Reflected FA Array with Control Board Enclosure

Fig. 6.13 3D Radiation Pattern of Reflected FA Array with Control Board Enclosure

6.2.2 Control board enclosure with connector simulations

The second set of control board enclosure simulations included a polymer block 57

where the connector should be. This block is a simplified version of the connector because it does not include pin cavities or metallic pins. Figure 6.14, 6.15, and 6.16 show the orientation and simulation results of a prototype FA simulation. The simulation setup matches Figure 6.8 through Figure 6.10 with the exception that a polymer connector block is placed within the connector cavity.

The results shown in Figure 6.16 are particularly surprising when compared to

Figure 6.10. It appears that the polymer connector blocks or reflects the propagation of

58 the reflected RF waves which pass through in Figure 6.10. The total gain of Figure 6.10 in the -Y direction is 4.20 dB, and the corresponding total gain in Figure 6.16 is -0.57 dB.

This means that the RF power being transmitted in Figure 6.10 is three times more than the transmitted power in Figure 6.13. A comparison of Figure 6.9 and Figure 6.15 shows a small amount of change. The shape of the S11 parameters is exactly the same, but the value of the S11 parameter at the lowest frequency is about 3dB different.

Fig. 6.14 Prototype FA in XY Orientation at Control Board Height

Fig. 6.15 S11 Parameter of a Prototype FA at Control Board Height with Control Board Enclosure and Connector

Fig. 6.16 3D Radiation Pattern of a Prototype FA at Control Board Height with the Control Board Enclosure and Connector

6.3 Simulations Including All Environmental Factors

A final set of simulations were designed to include all parasitic components in a single set of simulations. It included the encapsulation material with a thin layer of water and the control board enclosure with the polymer connector block. These simulations were used for a final comparison, and to suggest future implementation techniques for

HVAC systems. The first set of simulations shown, Figures 6.17, 6.18 and 6.19, is the prototype FA board in the best configuration simulated. It is oriented in such a way that impedance changes are minimized and antenna radiation is maximized.

After including all environmental factors, the S11 parameter shows a large number of non-ideal areas where RF signals will be passed through. Most of the non- ideal areas can be corrected by adding a matching network to transform the impedance of the antenna, and the main center frequency can be shifted by modifying the dimensions of the antenna to create an antenna that functions correctly. Figure 6.19 shows the 3D radiation pattern of the total gain at 2.5 GHz. The majority of the signal is directed out

the connector cavity, and a total gain of 4.78 dB is achieved. 60

Fig. 6.17 Prototype FA Simulation in Ideal Orientation with All Environmental Effects

Fig. 6.18 S11 Parameter of FA in Ideal Orientation with All Environmental Factors

Fig. 6.19 3D Radiation Pattern for Prototype FA in Ideal Orientation with All Environmental Factors

6.4 Recommendations

Based on the simulations presented here a few recommendations are made. In 62

Chapter 5, the ideal antenna optimization simulations pointed to an optimized FA array as the best choice for implementation. These simulations show that this may not be the case for implementation within a control board enclosure for a variety of reasons. First, the implementation of an array of antennas is more difficult and exact. The antenna array boards are separate and must have a very specific distance to improve the gain substantially, while not cancelling each other out. These more strenuous requirements will not be easily mass produced and implemented in a residential HVAC system.

Secondly, the simulations of Chapter 6 show that the total gain increases seen in Chapter

5 do not translate when the FA array is placed inside a control board enclosure. For these reasons, the recommendation is to focus on a standard UHF PCB antenna for future implementation within a residential HVAC system.

Next, it was shown that an encapsulation material can be simulated in HFSS with a UHF PCB FA. If enough information is provided about the encapsulation material, changes to the dimensions of the FA can be implemented to successfully correct for the negative effects of the encapsulation material. At this time, not enough information was provided about the encapsulation material, but more simulations and testing can create an optimized antenna design. Thus, the recommendation is that an encapsulation material can be implemented with the antenna board, but testing and or simulation will be required to retune the antenna to the correct center frequency.

Thirdly, these simulations show that orientation and antenna board placement is very important to total gain and the antenna impedance. Placing the antenna board in ideal orientation resulted in an increase of total gain by 6.29 dB when compared to

placing the antenna board on or near the standard control board height. This translates to a quadrupling of signal power propagating to the far fields.

7. CONCLUSIONS

A novel UHF PCB antenna has been designed and simulated. Recommendations for future implementations based on environmental effects have been made. The antenna takes into account three ideal optimizations that define the size of the ground plane, the number of layers the antenna has, and different array configurations. These optimizations provided a basis for the environmental effects simulations which can be used to identify the best way to implement the optimized antenna.

The results shown in Chapter 5 identify a two by one array of antennas, with a stacked antenna implemented with a 20% lambda ground plane as an ideally optimized antenna. However, the results shown in Chapter 6 are conflicting. Due to size constraints, surrounding metal, and aperture size a two by one array of antennas becomes unpractical. It is unpractical due to poor operation due to detuning from the surrounding

metal and precise placement requirements. As such, in Chapter 6 the study returns to a single UHF PCB F-Antenna design, and it the optimum orientation and placement of the antenna to receive the best signal propagation is shown.

Future work should include: measurements of S11 and gain parameters using an anechoic chamber, a simulated matching network to take into account parasitic matching components, the addition of the HVAC enclosure in HFSS simulations, and model an unpowered slot antenna that can boost the RF signal through the metal enclosure to

65 ensure better signal transmission. The measurements would provide more comparison points for the HFSS simulations, specifically the gain patterns. If the matching network is added, it will create a more complete simulation that includes component parasitic that more accurately matches real life measurements. If adding the HVAC enclosure in HFSS simulations is done correctly, it will show where the RF signal is propagating out of the enclosure. By knowing where the RF signal is propagating best, certain vents and other enclosure apertures may be redesigned or moved to optimize signal propagation. This final additional study will provide for an optional improvement to for a wireless HVAC system. The slot antenna improvement may be required for HVAC enclosures that are wholly metallic without vents or for HVAC enclosures with fewer vents to ensure RF signal propagation.

BIBLIOGRAPHY

[1] C. M. Harris, Dictionary of Architecture & Applications, New York: McGraw-Hill, 2003.

[2] Y. Tachwali, H. Refai and J. Fagan, "Minimizing HVAC Energy Consumption Using a Wireless Sensor Netwrok," in Industrial Electronics Society, 2007. IECON 2007. 33rd Annual Conference of the IEEE., 5-8 Nov. 2007.

[3] S. Ahmadi, I. Shames, F. Scotton, L. Huang, H. Sandberg, K. Johansson and B. Wahlberg, "Towards more Efficient Building Energy Management Systems," in Seventh International Conference on Creativity Support Systems (KICSS), 8-10 Nov. 2012.

[4] S. Sultan, T. Khan and S. Khatoon, "Implementation of HVAC System Through Wireless Sesnor Network," in Second International Conference on Communication Software and Networks, 2010. , 2010.

[5] S. J. Winick, "RF Interconnected HVAC System and Security System". United States Patent US 2005/0040943 A1, 24 February 2005.

[6] O. Tonguz, D. Stancil, A. C. A. Xhafa, P. Nikitin and D. Brodtkorb, "An Empirical Loss Model for HVAC Duct Systems," in IEEE Global Telecommunications Conference. GLOBECOM '01., 17-21 Nov. 2002.

[7] A. Xhafa, O. Tongus, A. Cepni, D. Stancil and P. B. D. Nikitin, "On the Capacity Limits of HVAC Duct Channel for High-Speed Internet Access," IEEE Transactions on Communications, vol. 52, pp. 335,342, February 2005.

[8] M. Jahn, M. Jentsch, C. Prause, F. A.-A. A. Pramudianto and R. Reiners, "The 66

Energy Aware Smart Home," in 5th International Conference on Future Information Technology (FutureTech), 21-23 May 2010.

[9] M. Alam and M. B. I. A. M. A. M. Raez, "A Review of Smart Homes--Past, Present, and Future," in IEEE Transactions on Systems, Man, and Cybernetics, Part C: Applications and Reviews, Nov. 2012.

[10] L. Tan and N. Wang, "Future Internet: The Internet of Things," in 3rd International Conference on Engineering (ICACTE), Chengdu, 20-22 Aug. 2010.

[11] B. S. Blanchard, System Engineering Management, Hoboken, New Jersey: Wiley, 2008.

[12] N. P. Suh, Axiomatic Design: Advances and Applications, Oxford, New York: Oxford University Press, 2001.

[13] "MC13211/212/213 Zigbee- Compliant Platform 2.4 GHz Low Power Transceiver for the IEEE 802.15.4 Standard plus Microcontroller Reference Manual," Freescale, May 2010. [Online]. Available: http://cache.freescale.com/files/rf_if/doc/ref_manual/MC1321xRM.pdf. [Accessed 01 January 2013].

[14] C. Soras, M. Karaboikis, G. Tsachtsiris and V. Makios, "Analysis and Design of an Inverted-F Antenna Printed on a PCMCIA Card for the 2.4 GHz ISM Band," IEEE Antennas and Propagation Magazine, vol. 44, no. 1, pp. 37, 44, Feb. 2002.

[15] M.-C. Huynh and W. Stutzman, "Ground Plane Effects on Planar Inverted-F Antennas," Microwaves, Antennas and Propogation, IEEE PRoceedings, vol. 150, no. 4, pp. 209,213, 8 Aug. 2003.

[16] M. Olmos, H. Hristov and R. Feick, "Inverted-F Antennas with Wideband Match Performance," Electronic Letters, vol. 38, no. 16, pp. 845, 847, 1 Aug. 2002.

[17] C. A. Balanis, Antenna Theory Analysis and Design, Third Edition ed., Hoboken, New Jersey: John Wilen & Sons, Inc., 2005.

[18] F. Ohnimus, J. Haberland, C. Tschoban, I. Ndip, K. Heumann, C. Kallmayer, S. Guttowski and K. Lang, "Design and Characterization of Small Encapsulated UHF RFID Tag for Wood Log Monitoring," in 2010 Loughborough Antennas and 67 Propogation Conference (LAPC), Loughborough, 8-9 Nov. 2010.

[19] J. Winkle, R.M., B. Chambers, B. McConnell and Bryant., "Design, Fabrication and Measurement of an Encapsulated Inverted F Dual Band Antenna for the Gather of Data on Seals at Seal Using SMS Over a GSM System," in Twelfth International Conference on Antennas and Propogation, (ICAP 2003), 31 March-3 April 2003.

APPENDICES

A. FUNCTIONAL DESIGN DECOMPOSITION OF WIRELESS

HVAC MOTOR

The information in the following Appendix is part of a Systems Engineering case study in creating a HVAC electronically commutated (ECM) motor that is capable of wireless communication. A short overview of the case study can be found in Chapter 2.

The functional design decomposition was created after a large amount of initial research and with specific customer requests in mind. One specific request was to implement wireless communication as a solution to achieve , , and . As such, is very specific and has a design decisions built in the functional requirement.

Axiomatic Design, or the use of a functional design decomposition, is useful for a variety of reasons. Some of these reasons include: the design decomposition can be used

68 as a visual communication between various groups within the company; the design decomposition can be used to ensure that a coupled design is not built and the independence axiom is maintained; and the design decomposition can be used to identify a path dependent solution to minimize design implementation mistakes. The independence axiom states that an FR can be achieved without affecting another FR. A coupled design occurs when the independence axiom is not maintained. The FRs and

DPs are interconnected in such a way that the design matrix does not result in either a diagonal or triangular matrix.

As a communication tool, the design decomposition provides a discussion point between managers, engineering groups, and customers. It gives a concise review of the functions that the customer desire, while removing any assumed solutions. If designed appropriately, the design decomposition may also be used as a tool to identify potential interfaces and overall design of a product.

The design decomposition is also very useful for identifying and maintaining the independence axiom, while ensuring a design is not coupled. Coupling in product design introduces requirement creep and additional costs into the project. The design decomposition can also be used to identify a path dependent solution. A path dependent solution is when the DPs of a design must be implemented in a specific order to achieve the FRs. An example is the construction of a house with a basement. The basement should be dug out and built before the upper levels of the house are built. If this is not done in the correct order, building the basement will become much more difficult.

Below, each figure contains a functional design decomposition. After each figure, a series of design matrices will be shown that show how the FRs and DPs are

interconnected. These design matrices can be monitored to ensure the independence axiom is maintained and no coupling is present. For instance, Fig A.1 is related to

Equation A.1. If the functional decomposition is simple enough a design equation may not be included.

Fig. A.1 Top Level Functional Design Decomposition

(A.1)

{ } [ ] { }

Fig. A.2 Design Decomposition of FR11

(A.2)

{ } [ ] { }

{ } [ ] { } (A.3)

Fig. A.3 Design Decomposition of FR12

{ } [ ] { } (A.4)

{ } [ ] { } (A.5)

Fig. A.4 Design Decomposition of FR13

{ } [ ] { } (A.6)

{ } [ ] { } (A.7)

Fig. A.5 Design Decomposition of FR14

Fig. A.6 Design Decomposition of FR15

{ } [ ] { } (A.8)

B. LQI AND RANGE MEASUREMENT TABLES

Table B.1 LQI Measurements for the FA Prototype Board at a Distance of 3.048 Meters

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -90.80 -72.50 -85.8 -90.45 -89.15 -82.65

1.22 m -87.95 -73.40 -72.6 -85.00 -87.00 -91.75

HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 75

0.61 m -69.40 -74.20 -71.05 -85.35 -93.70 -90.45

1.22 m -70.95 -75.15 -75.75 -82.25 -82.90 -

Table B.2 LQI Measurements for the FA Prototype Board at a Distance of 6.096 Meters

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -87.30 -85.50 -81.35 -95.00 -95.00 -89.15

1.22 m -89.80 -82.70 -78.65 -95.00 -95.00 -89.20

HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -87.10 -74.75 -72.90 -89.80 -90.45 -90.45

1.22 m -80.65 -84.40 -76.10 -86.75 -95.00 -

Table B.3 LQI Measurements for the MFA Prototype Board at a Distance of 3.048 Meters

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -82.35 -81.25 -83.15 -87.90 -95.00 -91.75

1.22 m -84.25 -81.70 -82.25 -95.00 -95.00 -93.70

HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -81.00 -75.80 -73.40 -89.15 -93.70 -92.40

1.22 m -80.10 -78.60 -88.60 -89.50 -94.35 -95.00

Table B.4 LQI Measurements for the MFA Prototype Board at a Distance of 6.096 Meters

HVAC Ventilation Duct Open

HVAC Access Panel Installed HVAC Access Panel Removed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -76.40 -76.80 -77.60 -95.00 -91.75 -95.00 1.22 m -85.85 -88.85 -88.25 -95.00 -95.00 -95.00 HVAC Ventilation Duct Closed

Door Open Door Closed Command 45°Left 0° 45° Right 45°Left 0° 45° Right Board (dBm) (dBm) (dBm) (dBm) (dBm) (dBm) Height 0.61 m -77.85 -77.70 -76.90 -88.20 -95.00 -88.50 1.22 m -93.70 -88.55 -88.85 -89.80 -95.00 -

C. ANTENNA OPTIMIZATION SIMULATION RESULTS

In the following appendix, a more complete set of antenna optimization simulations results reviewed in Chapter 5 will be shown. The results fall in three categories: ground plane variation simulations, stacked antenna simulations, and array simulations. Section D.1 will cover the ground plane variation simulations. No S11 parameters will be shown, because there were virtually no changes made to the S11 parameters, and those changes that do occur are enumerated in Chapter 5.

Section D.2 covers the stacked antenna simulations. A variety of S11 parameter comparisons are shown. These provide comparisons for the number of layers of the antenna for different ground plane sizes. Also, two 3D radiation patterns are provided for comparison to show that virtually no changes are made to the 3D radiation patterns.

Section D.3 covers the array simulations. Two types of arrays are shown: a 79

copied array and a reflected array. A copied array is when an antenna is copied and replicated down the x-axis with no shift in orientation, and is shown in Figure D.13 for review. A reflected array is when an antenna is reflected along the x-axis, and can be seen in Figure D.17 for review.

C.1 Ground Plane Variation Simulations

Fig. C.1 Prototype FA with a 0.2*λ Ground Plane Size

Fig. C.2 Prototype FA with a 0.3*λ Ground Plane Size

Fig. C.3 Prototype FA with a 0.4*λ Ground Plane Size

Fig. C.4 Prototype FA with a 0.6*λ Ground Plane Size

Fig. C.5 Prototype FA with a 0.8*λ Ground Plane Size

Fig. C.6 Prototype FA with a 1.0*λ Ground Plane Size

Fig. C.7 Prototype FA with a 1.0*λ Ground Plane Size

C.2 Stacked Antenna Simulations

Fig. C.8 S11 Plots of Various Stacked Prototype FAs with 0.2*λ Ground Plane Size

Fig. C.9 S11 Plots of Various Stacked Prototype FAs with 0.8*λ Ground Plane Size

Fig. C.10 S11 Plots of Various Stacked Prototype FAs with 1.0*λ Ground Plane Size

Fig. C.11 3D Radiation Pattern of Single Layer Prototype FA with 0.2*λ Ground Plane

Fig. C.12 3D Radiation Pattern of Single Layer Prototype FA with 1.0*λ Ground Plane

C.3 Array Simulations

Fig. C.13 Copied Prototype FA Array Orientation

Fig. C.14 2x1 Copied Prototype FA Array with 0.2*λ Between Antennas

Fig. C.15 2x1 Copied Prototype FA Array with 0.6*λ Between Antennas

Fig. C.16 2x1 Copied Prototype FA Array with 1.0*λ Between Antennas

Fig. C.17 2x1 Reflected Prototype FA Array Orientation

Fig. C.18 2x1 Reflected Prototype FA Array with 0.2*λ Between Antennas

Fig. C.19 2x1 Reflected Prototype FA Array with 0.6*λ Between Antennas

Fig. C.20 2x1 Reflected Prototype FA Array with 1.0*λ Between Antennas

D. ENVIRONMENTAL EFFECTS HFSS SIMULATION RESULTS

In the following appendix, a more complete series of simulations concerning environmental effects is provided. It will include three types of simulations: encapsulation with water simulations, control board enclosure with polymer connector simulations, and simulations including all environmental factors. Plots of S11 parameters and 3D radiation boundaries for various antenna orientations and setups are provided in each section.

Section E.1 will cover simulations which include the encapsulation material with a layer of water included. Three simulation orientations will be shown: a prototype FA, a

2x1 copied FA array, and a 2x1 reflected FA array. Orientation figures will not be shown in this section, because they were shown in Appendix C and the figure titles should

suffice. 90

Section E.2 shows simulations that include the control board enclosure with the polymer connector. Only prototype FA simulations are shown at this point because it was determined in section 6.2.1 that the array simulations were not providing adequate gain. Section E.3 shows the comprehensive simulations which include all environmental effects considered in this thesis. No orientation figures will be provided in section E.3, because the orientations have been reviewed in section E.2. These final simulations give an overview of which orientation and setup should work the best.

D.1 Encapsulation Material with Water Layer Simulations

Fig. D.1 S11 Parameter for Prototype FA with Encapsulation and Water Layers

Fig. D.2 3D Radiation Pattern of Prototype FA with Encapsulation and Water Layers

Fig. D.3 S11 Parameter for 2x1 Copied FA Array with Encapsulation and Water Layers

Fig. D.4 3D Radiation Pattern for 2x1 Copied FA Array with Encapsulation and Water Layers

Fig. D.5 S11 Parameter for 2x1 Reflected FA Array with Encapsulation and Water Layers

Fig. D.6 3D Radiation Pattern for 2x1 Reflected FA Array with Encapsulation and Water Layers

D.2 Control Board Enclosure with Polymer Connector Simulation

Fig. D.7 Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector

Fig. D.8 S11 Parameter for Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector

Fig. D.9 3D Radiation Pattern for Prototype FA in XZ Orientation with Control Board Enclosure and Polymer Connector

Fig. D.10 Prototype FA in XY Orientation at Control Board Height with Control Board Enclosure and Polymer Connector

Fig. D.11 S11 Parameter for Prototype FA in XY Orientation at Control Board Height with Control Board Enclosure and Polymer Connector

Fig. D.12 3D Radiation Pattern for Prototype FA in XZ Orientation at Control Board Height with Control Board Enclosure and Polymer Connector

Fig. D.13 Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector

Fig. D.14 S11 Parameter for Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector

Fig. D.15 3D Radiation Pattern for Prototype FA in XY Orientation Centered on the Connector Cavity with Control Board Enclosure and Polymer Connector

D.3 All Environmental Factor Simulations

Fig. D.16 S11 Parameter for Prototype FA in XZ Orientation with All Environmental Effects Considered

100

Fig. D.17 3D Radiation Pattern for Prototype FA in XZ Orientation with All Environmental Factors Included

Prototype FA in XY Orientation at Control Board Height with All Environmental Factors Added ANSOFT 0.00 Curve Info dB(S(1,1)) Setup1 : Sw eep1

-2.50

100

-5.00

-7.50

m4 dB(S(1,1)) -10.00

-12.50

-15.00 Name X Y m1 1.6900 -3.7222 m2 2.6900 -5.8214 m3 m3 3.1700 -16.6881 m4 3.8600 -9.5211 -17.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Freq [GHz]

Fig. D.18 S11 Parameter for Prototype FA in XY Orientation at Control Board Height with All Environmental Factors Included

101

Fig. D.19 3D Radiation Pattern of Prototype FA in XY Orientation at Control Board Height with All Environmental Effects Included

101

Fig. D.20 S11 Parameter of Prototype FA in XY Orientation Centered on the Connector with All Environmental Factors Included