Amplifiers, Sequencing, Phasing Lines, Noise Problems Tom Haddon, K5VH and New Modes of Operation
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High Frequency Communications – an Introductory Overview
High Frequency Communications – An Introductory Overview - Who, What, and Why? 13 August, 2012 Abstract: Over the past 60+ years the use and interest in the High Frequency (HF -> covers 1.8 – 30 MHz) band as a means to provide reliable global communications has come and gone based on the wide availability of the Internet, SATCOM communications, as well as various physical factors that impact HF propagation. As such, many people have forgotten that the HF band can be used to support point to point or even networked connectivity over 10’s to 1000’s of miles using a minimal set of infrastructure. This presentation provides a brief overview of HF, HF Communications, introduces its primary capabilities and potential applications, discusses tools which can be used to predict HF system performance, discusses key challenges when implementing HF systems, introduces Automatic Link Establishment (ALE) as a means of automating many HF systems, and lastly, where HF standards and capabilities are headed. Course Level: Entry Level with some medium complexity topics Agenda • HF Communications – Quick Summary • How does HF Propagation work? • HF - Who uses it? • HF Comms Standards – ALE and Others • HF Equipment - Who Makes it? • HF Comms System Design Considerations – General HF Radio System Block Diagram – HF Noise and Link Budgets – HF Propagation Prediction Tools – HF Antennas • Communications and Other Problems with HF Solutions • Summary and Conclusion • I‟d like to learn more = “Critical Point” 15-Aug-12 I Love HF, just about On the other hand… anybody can operate it! ? ? ? ? 15-Aug-12 HF Communications – Quick pretest • How does HF Communications work? a. -
Nested Loop Antennas This Low-Cost Five Band Loop Array Blends Into the Background
Nested Loop Antennas This low-cost five band loop array blends into the background. G. Scott Davis, N3FJP This multi-band nested loop antenna array replaces my tribander Yagi, which is only up 20 feet. Inspired by suggestions from Bill Wisel, K3KEI, I first tried a full wave 20 meter band square loop antenna. On the air comparisons with my low Yagi confirmed instantly that this design was a hands-down winner for working both local and distant stations. I replaced that mono-band loop with a nested loop array for the 20, 17, 15, 12, and 10 meter bands. The antenna blends into the surroundings, so I needed the morning sun shining directly on it to snap the lead photo. This became a nice father-son project with my son Brad, KB3MNE. Here’s how we built the antenna. Construction We constructed the square loops shown in Figure 1 according to the dimensions in Table 1. The loops hang from a tree limb in the vertical plane. Because I feed them This stealthy nested loop is almost invisible among the trees. from the bottom corners, the loops radiate horizontal polarization. Calculate the perimeter size, P, of each holes through the pipe for the loop wire. screws into the PVC to hang the dipole loop by dividing the frequency in MHz After you run the wire through the holes, connectors seen in Figure 2. wrap a bit of electrical tape on each side of into 1005 feet. Table 1 shows the loop Matching and Feeding dimensions. Start with the 20 meter loop, the wire next to the pipe to keep the wire from sliding and to give the pipe additional Each loop antenna feed point impedance is the largest loop. -
"Eggbeater"Antenna Vhf/Uhf ~ Part 1
"EGGBEATER"ANTENNA VHF/UHF ~ PART 1 ON6WG / F5VIF For the enthusiastic listeners or the licensed amateur station wishing to experiment with satellite transmissions without investing a large sum of money in rotators and tracking systems, here is a very competitive antenna. It will appeal to those with no space for large arrays, or for those who simply wish to experiment with circular polarization for terrestrial transmissions. Introduction This antenna was conceived mainly for high-speed digital transmission via satellite. Another reason was the need for a compact system due to the local environment of my station (mountainous region with high hills and obstacles too close to my station, no space to safely place rotative YAGI antennas). If the horizon is unreachable for RF signals , that leaves only the sky above us. To use the high-speed digital satellites, the level of signal reaching the TNC must be high enough to correctly decode the packets. For example, I mainly use an AEA/PK-96 TNC which requires at least 200 millivolts p-p at the input. To have this level when receiving 9600 Bd packets, there must be at least an S-3 showing on the S-Meter of my receiver. Design The antenna is made of two full waves loops , mounted at right angles to each other. Then coupled together, 90 degrees out of phase over a horizontal circular reflector. With this configuration the antenna is omni directional and circularly polarized. Changing the feeder connection from one loop to the other loop will effectively change the polarization between RHCP and LHCP. -
A Dual-Port, Dual-Polarized and Wideband Slot Rectenna for Ambient RF Energy Harvesting
A Dual-Port, Dual-Polarized and Wideband Slot Rectenna For Ambient RF Energy Harvesting Saqer S. Alja’afreh1, C. Song2, Y. Huang2, Lei Xing3, Qian Xu3. 1 Electrical Engineering Department, Mutah University, ALkarak, Jordan, [email protected] 2 Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom. 3 Department of Electronic Science and Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, China. Abstract—A dual-polarized rectangular slot rectenna is they are able to receive RF signals from multiple frequency proposed for ambient RF energy harvesting. It is designed in a bands like designs in [4-7]. In [4], a novel Hexa-band rectenna compact size of 55 × 55 ×1.0 mm3 and operates in a wideband that covers a part of the digital TV, most cellular mobile bands operation between 1.7 to 2.7 GHz. The antenna has a two-port and WLAN bands. Broadband antennas. In [7], a broadband structure, which is fed using perpendicular CPW and microstrip line, respectively. To maintain both the adaptive dual-polarization cross dipole rectenna has been designed for impedance tuning and the adaptive power flow capability, the RF energy harvesting over frequency range on 1.8-2.5 GHz. rectenna utilizes a novel rectifier topology in which two shunt (2) antennas for wireless energy harvesting (WEH) should diodes are used between the DC block capacitor and the series have the ability of receiving wireless signals from different diode. The simulation results show that RF-DC conversion polarization. Therefore, rectennas have polarization diversity efficiency is greater 40% within the frequency band of like circular polarization [7]; dual polarization [8] and all interested at -3.0 dBm received power. -
Enhancing the Coverage Area of a WI-FI Access Point Using Cantenna
ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. 2, Issue 4, April 2015 Enhancing the Coverage Area of a WI-FI Access Point Using Cantenna B.Anandhaprabakaran#1, S.Shanmugam*2,J.Sridhar*3S.Ajaykumar#4 #2-4student #1Assistant Professor, Sri Ramakrishna Engineering College, Coimbatore, Tamilnadu, India Abstract: “The next decade will be the Wireless Era.” – Intel Executive Sean Maloney and other executives framed. Today’s network especially LAN has drastically changed. People expect that they should not be bound to the network. In this scenario, Wireless (WLAN) offers tangible benefits over traditional wired networking. Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs). Wi-Fi works on three modes namely Ad hoc, Infrastructure and Extended modes. Ad hoc network is P2P mode. Ad hoc does not use any intermediary device such as Access Point. Infra Structure and Extended modes use Access Point as interface between wireless clients. The wireless network is formed by connecting all the wireless clients to the AP. Single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors. The coverage area depends upon the location where the AP is being placed. The AP has the traditional Omni directional antenna The aim of this project is to increase the coverage area of an AP by replacing the traditional Omni directional antenna with Bi-quad antenna with parabolic reflector. -
Class C Pool of Questions
Class C Pool of Questions T2 1. What is the most common repeater frequency offset in the 2 meter band? T2 2. What is the national calling frequency for FM simplex operations in the 70 cm band? T2 3. What is a common repeater frequency offset in the 70 cm band? T2 4. What is an appropriate way to call another station on a repeater if you know the other station's call sign? T2 5. How should you respond to a station calling CQ? T2 6. What must an amateur operator do when making on-air transmissions to test equipment or antennas? T2 7. Which of the following is true when making a test transmission? T2 8. What is the meaning of the procedural signal “CQ”? T2 9. What brief statement is often transmitted in place of “CQ” to indicate that you are listening on a repeater? T2 10. What is a band plan, beyond the privileges established by the SMA? T2 11. Which of the following is an SMA rule regarding power levels used in the amateur bands, under normal, non-distress circumstances? T2 12. Which of the following is a guideline to use when choosing an operating frequency for calling CQ? T2B – VHF/UHF operating practices: SSB phone; FM repeater; simplex; splits and shifts; CTCSS; DTMF; tone squelch; carrier squelch; phonetics; operational problem resolution; Q signals T2 1. What is the term used to describe an amateur station that is transmitting and receiving on the same frequency? T2 2. What is the term used to describe the use of a sub-audible tone transmitted with normal voice audio to open the squelch of a receiver? T2 3. -
An Electrically Small Multi-Port Loop Antenna for Direction of Arrival Estimation
c 2014 Robert A. Scott AN ELECTRICALLY SMALL MULTI-PORT LOOP ANTENNA FOR DIRECTION OF ARRIVAL ESTIMATION BY ROBERT A. SCOTT THESIS Submitted in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Computer Engineering in the Graduate College of the University of Illinois at Urbana-Champaign, 2014 Urbana, Illinois Adviser: Professor Jennifer T. Bernhard ABSTRACT Direction of arrival (DoA) estimation or direction finding (DF) requires mul- tiple sensors to determine the direction from which an incoming signal orig- inates. These antennas are often loops or dipoles oriented in a manner such as to obtain as much information about the incoming signal as possible. For direction finding at frequencies with larger wavelengths, the size of the array can become quite large. In order to reduce the size of the array, electri- cally small elements may be used. Furthermore, a reduction in the number of necessary elements can help to accomplish the goal of miniaturization. The proposed antenna uses both of these methods, a reduction in size and a reduction in the necessary number of elements. A multi-port loop antenna is capable of operating in two distinct, orthogo- nal modes { a loop mode and a dipole mode. The mode in which the antenna operates depends on the phase of the signal at each port. Because each el- ement effectively serves as two distinct sensors, the number of elements in an DoA array is reduced by a factor of two. This thesis demonstrates that an array of these antennas accomplishes azimuthal DoA estimation with 18 degree maximum error and an average error of 4.3 degrees. -
Analysis of Crossed Dipole to Obtain Circular Polarization Applying Characteristic Modes Techniques
Analysis of crossed dipole to obtain circular polarization applying Characteristic Modes techniques Juan Pablo Ciafardini (1), Eva Antonino Daviu (2), Marta Cabedo Fabrés (2), Nora Mohamed Mohamed-Hicho (2), José Alberto Bava (1), Miguel Ferrando Bataller (2). (1) Dpto. de Electrotecnia. Facultad de Ingeniería, Universidad Nacional de La Plata. Calle 48 y 116 - La Plata (1900), Argentina. [email protected] (2) Instituto de Telecomunicaciones y Aplicaciones Multimedia. Edificio 8G. Planta 4ª, acceso D. Universidad Politécnica Valencia. Camino de Vera, s/n46022 Valencia. España. [email protected] Abstract— The crossed dipole is a common type of antenna developed to achieve wider bandwidth impedance compared that is used to generate circularly polarized radiation in a wide to the original design. In 1961 a new type of crossed dipole frequency range. This antenna was originally developed in the antenna, which used a single feed, was developed for 1930s and today is used in many wireless communication circular polarization radiation [5], Bolster demonstrated systems, including broadcast services, satellite theoretically and experimentally that single-feed crossed communications, mobile communications, global navigation systems satellite system (GNSS), radio frequency identification dipoles connected in parallel if the lengths of the dipoles (RFID), wireless local area networks (WLANs) and global were such that the real parts of their input admittances were interoperability for microwave access (WiMAX). equal and the phase angles of their input admittances This paper shows that it is possible to obtain circular differed by 90º. Based on these conditions, numerous polarization with two cross dipoles with different lengths and single-feed circularly polarized crossed dipole antennas connected in parallel by applying the Theory of Characteristic have been designed [5] - [25]. -
The 3-D Folded Loop Antenna
The 33---DD Folded Loop Antenna Dave Cuthbert WX7G Introduction This article will introduce you to an antenna I call the 3-Dimensional Folded Loop. This antenna is the result of my continuing efforts to compact full-size antennas by folding and bending the elements. I will first describe the basic 3-DFL and then provide construction details for the 2-meter and 10-meter 3-DFL antennas. Here are some features of the 3-DFL: • Reduced height and footprint • Full-sized antenna performance • Wide bandwidth • Ground independent • Can be built using standard hardware store parts Description The 3-D Folded Loop, or simply the 3-DFL, is a one-wavelength loop that is reduced in height and width by being folded into three dimensions. A 28-MHz loop that is normally 9 feet on a side becomes a box-shaped antenna that is 3 by 3 by 5 feet. It exhibits performance that is competitive with a ground plane yet requires only 15 square feet of ground area versus 50 for the ground plane. So, compared to a ground plane it is only 60% as tall and has a footprint only 30% as large. And the 2-meter 3-DFL is so compact it can be placed on a table and connected to your HT for added range and reduced RF at the operating position. 1 3-DFL Theory of Operation The familiar one-wavelength square loop is shown in Fig. 1 and is fed in the center of one vertical wire. Note that the current in the vertical wires is high while the current in the horizontal wires and is low. -
A Flexible 2.45 Ghz Rectenna Using Electrically Small Loop Antenna
A Flexible 2.45 GHz Rectenna Using Electrically Small Loop Antenna Khaled Aljaloud1,2, Kin-Fai Tong1 1Electronic and Electrical Engineering Department, University College London, London, UK, [email protected] 2Electrical Engineering Department, King Saud University, Riyadh, Saudi Arabia Abstract—We present the concept and design of a compact schlocky diode connected in series to one of the two feed flexible electromagnetic energy-harvesting system using electri- terminals of the antenna and to the coplanar transmission line, cally small loop antenna. In order to make the integration of the a capacitor to minimize the ripple level. The reported system system with other devices simpler, it is designed as an integrated system in such a way that the collector element and the rectifier in this letter is sufficiently capable of reusing low microwave circuit are mounted on the same side of the substrate. The energy for both flat and curved configurations. rectenna is designed and fabricated on flexible substrate, and its performance is verified through measurement for both flat and curved configurations. The DC output power and the efficiency II. DESIGN AND RESULT are investigated with respect to power density and frequency. It is observed through measurements that the proposed system The two main parts of rectenna system are largely designed can achieve 72% conversion efficiency for low input power level, individually and unified through the matching network. In this -11 dBm (corresponding power density 0.2 W=m2), while at the work, the proposed rectenna is built as an integral system, and same time occupying a smaller footprint area compared to the thus the rectifier circuit is matched to the collector to maximize existing work. -
Design of Narrow-Wall Slotted Waveguide Antenna with V-Shaped Metal Reflector for X
2018 International Symposium on Antennas and Propagation (ISAP 2018) [ThE2-5] October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea Design of Narrow-wall Slotted Waveguide Antenna with V-shaped Metal Reflector for X- Band Radar Application Derry Permana Yusuf, Fitri Yuli Zulkifli, and Eko Tjipto Rahardjo Antenna Propagation and Microwave Research Group, Electrical Engineering Department, Universitas Indonesia Depok, Indonesia Abstract - Slotted waveguide antenna with wide bandwidth match to side lobe level requirement. Later, two metal sheets characteristics is designed at the 9.4-GHz frequency (X-band) as metal reflector are attached to the SWA edges to focus its for radar application. The antenna design consists of 200 narrow-wall slots with novel design of V-shaped metal reflector azimuth plane beam. The reflection coefficient, radiation to enhance side lobe level (SLL) and gain. New optimized slot pattern plots, and gain results of the antenna are reported. design results in SLL of -31.9 dB. The simulation results show 36.7 dBi antenna gain and 780 MHz bandwidth (8.67-9.45 GHz) for VSWR of 1.5. 2. Antenna Configuration Index Terms — slotted waveguide antenna, X-band, narrow- The 3-D view of the proposed antenna configuration is wall slots, high gain, metal reflector, radar shown in Fig 1. The antenna configuration consists of narrow wall slot waveguide with V-shaped metal reflector. The target frequency is 9.4 GHz. The slot antenna dimension 1. Introduction with its parameters is shown in Fig. 2. The antenna radiates Radar is essential component used for detecting hazards horizontal polarization and determines the parameters w = (such as coastlines, islands, icebergs, other objects or ships), 1.58 mm and t = 1.25 mm. -
Broadband Antenna 1
Broadband Antenna Broadband Antenna Chapter 4 1 Broadband Antenna Learning Outcome • At the end of this chapter student should able to: – To design and evaluate various antenna to meet application requirements for • Loops antenna • Helix antenna • Yagi Uda antenna 2 Broadband Antenna What is broadband antenna? • The advent of broadband system in wireless communication area has demanded the design of antennas that must operate effectively over a wide range of frequencies. • An antenna with wide bandwidth is referred to as a broadband antenna. • But the question is, wide bandwidth mean how much bandwidth? The term "broadband" is a relative measure of bandwidth and varies with the circumstances. 3 Broadband Antenna Bandwidth Bandwidth is computed in two ways: • (1) (4.1) where fu and fl are the upper and lower frequencies of operation for which satisfactory performance is obtained. fc is the center frequency. • (2) (4.2) Note: The bandwidth of narrow band antenna is usually expressed as a percentage using equation (4.1), whereas wideband antenna are quoted as a ratio using equation (4.2). 4 Broadband Antenna Broadband Antenna • The definition of a broadband antenna is somewhat arbitrary and depends on the particular antenna. • If the impendence and pattern of an antenna do not change significantly over about an octave ( fu / fl =2) or more, it will classified as a broadband antenna". • In this chapter we will focus on – Loops antenna – Helix antenna – Yagi uda antenna – Log periodic antenna* 5 Broadband Antenna LOOP ANTENNA 6 Broadband Antenna Loops Antenna • Another simple, inexpensive, and very versatile antenna type is the loop antenna.