DOCSLIB.ORG

Electronic Scanned Array Design John S. Williams

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electronic Scanned Array Design John S. Williams Electronic Scanned Array Design SCF01 John S. Williams The Aerospace Corporation (retired) [email protected] Slide 1 of 255 Course Objectives • Provide a basic understanding of ESA design principles, history and applications – Presentation will focus on antenna hardware – Radar antennas are the focus of this presentation • Communications and receive antennas differ only in details – ESA functionality enables or enhances radar modes but radar modes will not be addressed in any detail Slide 2 SCF01 Electronic Scanned Array Design of 255 Abstract Design Principles and Approaches GfGeneral design principles of aperture antennas are applied to the specific case of ESA design. System applications set the framework for requirements allocation and flowdown. Antenna Architectures and Functional Partitioning The advantages and disadvantages of ESA and reflector antennas as well as ESA feeds for reflectors are compared and contrasted. Common ESA design issues are described, including array partitioning and subarrays, lattice tradeoffs, feed design, causes and mitigation of sidelobes, beam steering approaches and techniques for beam shaping. Numerical examples using Matlab illustrate performance of specific designs. Practical Design Considerations ESA performance is constrained by the selection and limitations of specific components. Objectives of size, weight, power, thermal dissipation, performance and cost drive tradeoffs among radiating elements, T/R modules, monolithic microwave integrated circuits (MMICs), microwave distribution and packaging. Proposed and Operational Examples Recent radar satellite designs will be assessed to illustrate actual performance and design tradeoffs. Current L-band syyppstem proposals contrast different desigppgn approaches. Slide 3 SCF01 Electronic Scanned Array Design of 255 Antennas • One of the most important determinants of microwave system (radar, communications, other) performance • Requirements are determined by system performance allocation and flow-down • Attributes include: – Beam width, shape and sidelobes • Uniform illumination sidelobes -13 dB (rectangular aperture) or -17 dB (circular aperture) are too high for most purposes – Instantaneous and tunable bandwidth –Size • SAR (square) vs GMTI (rectangular) Aspect Ratios • Deployment – Thermal Dissipation – Weight –Cost • Thermal dissipation and power consumption will restrict system duty factor Slide 4 SCF01 Electronic Scanned Array Design of 255 Electronicallyyy() Scanned Array(ESA) • An ESA combines multiple elements with phase or time delays to form a beam in a specified direction – In contrast to a mechanically steered antenna physically rotates an antenna to point a beam in a specified direction • Phase or time delayyq is required to scan the beam • Gain control is required for beam shaping • ESA’s commonly include amplifiers – overcome distribution and control loss – Replace transmitter power amplifier (TWTA) Slide 5 SCF01 Electronic Scanned Array Design of 255 Reflector Antenna Radar Block Diagram Exciter Transmitter bal Frequency mm Data request Control & Timing Processor Gi Antenna Reference Duplexer Radar data Signal Processor Receiver Receiver Protection Power Supply ESA incorporates functions shown in dashed box Slide 6 SCF01 Electronic Scanned Array Design of 255 Electronically Scanned Array Radar Block Diagram TRM s) Exciter on ii (( TRM TRM TRM anifold Distribut Frequency MM TRM Data request Control Processor & Timing B TRM Reference e TRM orming & Logic ff a TRM m TRM Beam Power TRM Radar data Signal Processor Receiver(s) TRM Power Supply ESA incorporates functions shown in dashed box Slide 7 SCF01 Electronic Scanned Array Design of 255 ESA Benefits • Multiple beams • Instantaneous beam steering (agile beam) – Reduces slew and settle time • Mainlobe shaping, sidelobe control and nulling for clutter and interference mitigation • Multiple phase centers for MTI & multi-channel SAR – Enables angle of arrival measurement – Additional degrees of freedom for clutter and interference mitigation • Multiple concurrent radar modes. • Lower loss between amplifiers and free space • Inherent redundancy (multiple elements) – Graceful degradation • Electronic Attack (EA) with very high Effective Radiated Power (ERP) • Stealth – Better match to free space – much less reflection/reradiation • Antenna surface deformation (deliberate or accidental) may be compensated • Space combining (low loss) of solid state power amplifiers Slide 8 SCF01 Electronic Scanned Array Design of 255 ESA Performance Improvement 26 -3 dB • Multiple Azimuth Beam 24 – Improved SAR resolution 22 • MltilMultiple Eleva tion Beam 20 – Improved stripmap area km) (( 18 rate ← Boresight 16 – SCORE (SCan On Range Range Receive) 14 12 Sensor altitude is 10.0 km 10 Range to horizon is 357.3 km Boresight range is 20.0 km 8 Grazing angle = 30.0° -10 -5 0 5 10 Cross Rangg(e (km) Slide 9 SCF01 Electronic Scanned Array Design of 255 Technology Environment • ESAs have recently become very prevalent for the sole reason that they have become much more affordable (they were always known to offer significant benefits but were unaffordable) • T/R modules are a small fraction of radar system cost and a very small fraction of system cost Slide 10 SCF01 Electronic Scanned Array Design of 255 Aperture Design Slide 11 SCF01 Electronic Scanned Array Design of 255 Antenna Function • Antenna objective is to create a current/voltage distribution which creates a specified beam pattern or v/v. – Omni directional radio signals of little use (except for broadcasting) • Difficult to arrange in general – Arrays permit a sampled representation of current/voltage permiiitting a lmost any des ire d arrangement • Two design approaches – analysis and synthesis Slide 12 SCF01 Electronic Scanned Array Design of 255 Basic Appperture Shapes b a •Sqqpuare aperture • Round aperture – 4 by 8 wavelengths – 3 wavelengths radius – First sidelobe is -13.2 dB – First sidelobe at -17.8 dB – 3 dB beamwidth = ± 0.866 λ/D – 3 dB beamwidth = ± 1.03 λ/D – first null at ± λ/D – first null at ± 1.22 λ/D From Balanis “Antenna Theory” Chapter 11 Slide 13 SCF01 Electronic Scanned Array Design of 255 Analysis Regions (exact to approximate) Fresnel or Fraunhofer Near Field Transition or Far Field Region Region Region tenna nn A Nominal Beamwidth 2 D2 D2 D2 D2 2D λ 0 For = 3cm and 16λ 4λ 2λ λ λ D = 1 meter 2m 8m 17m 33m 67m D = 10 meter 208m 1,667m 3,333m 6,667m 833m Illustration from Lynch (© SciTech Publishing,Slide Inc), 14 SCF01 Electronic Scanned Array Design of 255 Regions EtEvanescent NFildNear Field FFildFar Field Fresnel Fraunhofer Near limit 0 3λ 2D² /λ Far limit 3λ 2D²/λ∞ Power decay R-n 1R-1 E and H No Yes Yes orthogonal Ω Z0 = 377 No Yes Yes • Laser Pointer • Ȝ = 630 nm, D = 1 mm => farfield at 3 meters Slide 15 SCF01 Electronic Scanned Array Design of 255 Another Visualization 4λ Slide 16 SCF01 Electronic Scanned Array Design 3λ 2D²/λ of 255 General Concepts • Linearit y and superpos ition • Reciprocity (Lorenz) – System behavior is independent of direction of energy transfer, ie antenna pattern ihis the same for transm it an d rece ive • Antenna pattern is the Fourier transform of aperture illumination – Discrete (sampled) vs continuous – The sample interval is the element spacing – λ/2 element spacing assures no grating lobes (Nyquist-Shannon sampling theorem) – Reso lu tion lim it (Ray le ig h cr iter ia ) – Round vs square • Projected aperture (cosine θ dependence) – Wheeler - Pozar • Polarization and principal planes •Radar R an ge E quati on Slide 17 SCF01 Electronic Scanned Array Design of 255 Resolution • RtiditlltdtbdidthRange measurement is directly related to bandwidth – Wide bandwidth waveform (eg chirp) required •AnAnglegle mmeasurementeasurement isis ddirectlyirectly relatedrelated to aantennantenna (ape(aperture)rture) size – Can generate “synthetic” apertures larger than physical antenna size by exploiting own platform motion • Angular resolution (Rayleigh criterion) – Coherent or non-coherent – Deconvolution of PSF allows higher (super) resolution subject to S/N – Consider two point sources (sinx/x) separated by small distance, fit sinx ’/x ’ an d ta ke difference, loo k a t Pd/Pfa – Elements spaced closer than Ȝ/2 potentially provide better resolution Slide 18 SCF01 Electronic Scanned Array Design of 255 Projjpected Aperture • Projected aperture is the apparent angular extent of the aperture as viewed from a specified direction • AtAntenna gai n is propor tiona ltl to pro jec tdted aper ture • Harold A. Wheeler derived this relationship in an early paper Broadside θ=30 θ=60 θ=90 Slide 19 θ=0 SCF01 Electronic Scanned Array Design of 255 Radar Ranggqe Equation • Radar range determined by antenna size (area), transmit power, receive noise figure and bandwidth P G262< SNR = t 3 4 (4:) kTeBF LR Pt = transmit power G = antenna gain λ = wavelthlength σ = target cross section k = Boltzmann's constant T = system temperature B = system bandwidth F = system noise figure L = system losses R = range to target Slide 20 SCF01 Electronic Scanned Array Design of 255 Friis Transmission Equation • Ratio of power received to power transmitted – Describes one-way radio links – Assumes antennas are aligned – Factor in parenthesis is free space loss P 6 2 r = G G P t r 4:R t 3 4 Pr = received power Pt = transmitted power Gt = transmit antenna gain Gr = receive antenna gain Slide 21 SCF01 Electronic Scanned Array Design of 255 Noise Eqqguivalent Sigma Zero 4:r 3 2Lsin3 k TB NESZ(< )= i B 0 6 P G G c= 2 2 3 4 t r pd
Load more

Recommended publications
  • Howard Hughes
    Howard Hughes Howard Hughes September 24, 1905 Born Houston, Texas, USA April 5, 1976 (aged 70) Died Houston, Texas, USA Chairman, Hughes Aircraft; Occupation industrialist; aviator; engineer; film producer Net worth US$12.8 bn (1958 Forbes 400) Ella Rice (1925-1929) Spouse Terry Moore (1949-1976) Jean Peters (1957-1971) For the Welsh murderer, see Howard Hughes (murderer). Howard Robard Hughes, Jr. (September 24, 1905 – April 5, 1976) was, in his time, an aviator, engineer, industrialist, film producer and director, a palgrave, a playboy, an eccentric, and one of the wealthiest people in the world. He is famous for setting multiple, world air-speed records, building the Hughes H-1 Racer and H-4 Hercules airplanes, producing the movies Hell's Angels and The Outlaw, owning and expanding TWA, his enormous intellect[1], and for his debilitating eccentric behavior in later life. Early years Hughes was born in Houston, Texas, on 24 September or 24 December 1905. Hughes claimed his birthday was Christmas Eve, although some biographers debate his exact birth date, (according to NNDB.com, it was most likely "the more mundane date of September 24"[2] ). His parents were Allene Stone Gano Hughes (a descendant of Catherine of Valois, Dowager Queen of England, by second husband Owen Tudor) [3][4] and Howard R. Hughes, Sr., who patented the tri-cone roller bit, which 1 allowed rotary drilling for oil in previously inaccessible places. Howard R. Hughes, Sr. founded Hughes Tool Company in 1909 to commercialize this invention. Hughes grew up under the strong influence of his mother, who was obsessed with protecting her son from all germs and diseases.
    [Show full text]
  • Reorganization Strengthened Delco to Deal with a Challenging
    reorganization strengthened Delco to deal business that is succeeding. Employee byes are with a challenging competitive environment. disrupted, customer relationships must be pre· making possible new steps toward rightsizing served. shareholders need to be assured and sat· and structural cost reductions, accelerated Isfied even as the need to do daily banlc with technology introduction into GM's North the competitIOn continues. /\merican Operanons, and a realignment of Yet. at each stage in our company's history. International operations to sharpen focus on Hughes has always been a place where people profitable growth accept change as challenge - a company that's been too busy defining the future to be afraid As the fastest growing segment of Hughes of it. We are confident the changes we're mak· Electronics, Telecommunications and Space ing in 1997 will serve to solidify the one con· posted a 33% growth rate in 1996 - with total stant through Hughes' long history - securing revenues of $4.1 billion. Hughes Space and this company's legacy as an industry leader for Communications increased revenues by 21 %, years to come. Hughes Nerwork Systems broke the $1 billion revenue threshold for the first time, while the PanAmSat merger announcement marked a major milestone on the path to a truly global C. Michael Armstrong communications service. DIRECTV in the Chairman of the Board and United States, attained a subscriber base of 2.5 Chief Executive Officer million in early 1997, making it equivalent in size to the nation's seventh largest cable televi­ sion company. Using technology, talent and investment to lead in markets, to build new businesses, to cre­ Charles H.
    [Show full text]
  • Before the Federal Communications Commission Washington DC 20554
    Before the Federal Communications Commission Washington DC 20554 In the Matter of ) ) Unlicensed Use of the 6 GHz Band ) ET Docket No. 18-295 ) Expanding Flexible Use of the Mid-Band ) GN Docket No. 17-183 Spectrum Between 3.17 and 24 GHz ) COMMENTS OF THE FIXED WIRELESS COMMUNICATIONS COALITION Cheng-yi Liu Mitchell Lazarus FLETCHER, HEALD & HILDRETH, P.L.C. 1300 North 17th Street, 11th Floor Arlington, VA 22209 703-812-0400 Counsel for the Fixed Wireless February 15, 2019 Communications Coalition TABLE OF CONTENTS A. Summary .................................................................................................................................. 1 B. 6 GHz FS Bands and the Public Interest ................................................................................. 6 C. Fallacies on RLAN/FS Interference ........................................................................................ 9 1. High-off-the-ground FS antennas .................................................................................... 9 2. Indoor operation ............................................................................................................. 10 3. Statistical interference prediction .................................................................................. 10 D. Automatic Frequency Control Using Exclusion Zones ......................................................... 13 E. Multipath Fading and Fade Margin ....................................................................................... 15 1. Momentary interference
    [Show full text]
  • Agile 3-D Beam-Steering for 60 Ghz Wireless Networks Anfu Zhou∗, Leilei Wu∗, Shaoqing Xu∗, Huadong Ma∗, Teng Wei†, Xinyu Zhang‡ ∗ Beijing Key Lab of Intell
    Following the Shadow: Agile 3-D Beam-Steering for 60 GHz Wireless Networks Anfu Zhou∗, Leilei Wu∗, Shaoqing Xu∗, Huadong Ma∗, Teng Weiy, Xinyu Zhangz ∗ Beijing Key Lab of Intell. Telecomm. Software and Multimedia, Beijing University of Posts and Telecomm. y Department of Electrical and Computer Engineering, University of Wisconsin-Madison z Department of Electrical and Computer Engineering, University of California San Diego Email: fzhouanfu,layla,donggua,[email protected], [email protected], [email protected] Abstract—60 GHz networks, with multi-Gbps bitrate, are Much effort has been devoted to design agile beam-steering, considered as the enabling technology for emerging applications from the hierarchical beam scanning defined in standards [1], such as wireless Virtual Reality (VR) and 4K/8K real-time [9], to heuristic-based shortcuts [10], [11] or sensing-inspired Miracast. However, user motion, and even orientation change, can cause mis-alignment between 60 GHz transceivers’ directional solutions [12], [13]. However, these methods mainly focus on beams, thus causing severe link outage. Within the practical 3D two dimensional (2D) beam-steering, e.g., assuming a phased- spaces, the combination of location and orientation dynamics array that can steer the main beam among different angles leads to exponential growth of beam searching complexity, which within a 2D plane. In practice, the users and radios move in 3D substantially exacerbates the outage and hinders fast recovery. space; and a 60 GHz array can comprise a planar “matrix” of In this paper, we first conduct an extensive measurement to analyze the impact of 3D motion on 60 GHz link performance, antenna elements, steering the beams towards different angles in the context of VR and Miracast applications.
    [Show full text]
  • Reading Comprehension
    READING COMPREHENSION 4 Howard Hughes, The Aviator Read the text about the life of the billionaire Howard Hughes. • Then choose the correct answer (A, B, C or D) for questions 1–7. • Write your answers in the spaces provided. • The rst one (0) has been done for you. Howard Hughes, The Aviator by Jennifer Rosenberg Howard Hughes’ Childhood Though he grew up in a wealthy household, Howard Hughes Jr. had diffi culty focusing on school and changed schools often. Rather than sitting in a classroom, Hughes preferred to learn by tinkering with mechanical things. For instance, when his mother forbade him from having a motorcycle, he built one by building a motor and adding it to his bicycle. Hughes was a loner in his youth; with one notable exception, Hughes never really had any friends. Tragedy and Wealth When Hughes was just 16-years old, his doting mother passed away. And then not even two years later, his father also suddenly died. Howard Hughes received 75% of his father’s million-dollar estate; the other 25% went to relatives. Hughes immediately disagreed with his relatives over the running of Hughes Tool Company but being only 18-years old, Hughes could not do anything about it because he would not legally be considered an adult until age 21. Frustrated but determined, Hughes went to court and got a judge to grant him legal adulthood. He then bought out his relatives’ shares of the company. At age 19, Hughes became full owner of the company and also got married (to Ella Rice).
    [Show full text]
  • Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers Including Near-Field Coupling Analysis
    UNIVERSITY OF CALIFORNIA Los Angeles Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers including Near-field Coupling Analysis A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Electrical Engineering by Ilkyu Kim 2012 c Copyright by Ilkyu Kim 2012 ABSTRACT OF THE DISSERTATION Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers including Near-field Coupling Analysis by Ilkyu Kim Doctor of Philosophy in Electrical Engineering University of California, Los Angeles, 2012 Professor Yahya Rahmat-Samii, Chair Recent developments in mobile communications have led to an increased appearance of short-range communications and high data-rate signal transmission. New technologies provides the need for an accurate near-field coupling analysis and novel antenna designs. An ability to effectively estimate the coupling within the near-field region is required to realize short-range communications. Currently, two common techniques that are applicable to the near-field coupling problem are 1) integral form of coupling formula and 2) generalized Friis formula. These formulas are investigated with an emphasis on straightforward calculation and accuracy for various distances between the two antennas. The coupling formulas are computed for a variety of antennas, and several antenna configurations are evaluated through full-wave simulation and indoor measurement in order to validate these techniques. In addition, this research aims to design multi- functional and high performance antennas based on MEMS (Microelectromechanical ii Systems) switches, EBG (Electromagnetic Bandgap) structures, and septum polarizers. A MEMS switch is incorporated into a slot loaded patch antenna to attain frequency reconfigurability.
    [Show full text]
  • Beamforming in 5G Mm-Wave Radio Networks Importance of Frequency Multiplexing for Users in Urban Macro Environments
    UPTEC E 20002 Examensarbete 30 hp Mars 2020 Beamforming in 5G mm-wave radio networks Importance of frequency multiplexing for users in urban macro environments Carl Lutnaes Abstract Beamforming in 5G mm-wave radio networks Carl Lutnaes Teknisk- naturvetenskaplig fakultet UTH-enheten 5G brings a few key technological improvements compared to previous generations in telecommunications. These include, but are not limited to, greater speeds, Besöksadress: increased capacity and lower latency. These improvements are in part due to using Ångströmlaboratoriet Lägerhyddsvägen 1 high band frequencies, where increased capacity is found. By advancements in Hus 4, Plan 0 various technologies, mobile broadband traffic has become increasingly chatty, i.e. more small packets are being sent. From a capacity standpoint this Postadress: characteristic poses a challenge for early 5G millimeter-wave advanced antenna Box 536 751 21 Uppsala systems. This thesis investigates if network performance of 5G millimetre-wave systems can be improved by increasing the utilisation of the bandwidth by using Telefon: adaptive beamforming. Two adaptive codebook approaches are proposed; a single- 018 – 471 30 03 beam and a multi-beam approach. The simulations are performed in an outdoor urban Telefax: macro scenario. The results show that for a small packet scenario with good 018 – 471 30 00 coverage the ability to frequency multiplex users is important for good network performance. Hemsida: http://www.teknat.uu.se/student Handledare: Erik Larsson Ämnesgranskare: Steffi Knorn Examinator: Tomas Nyberg ISSN: 1654-7616, UPTEC E 20002 Popul¨arvetenskaplig sammanfattning 5G ¨arn¨astagenerations telekommunikationsstandard. Nya 5G–n¨atverksprodukter kommer att ha ¨okad kapacitet vilket leder till snabbare data¨overf¨oringaroch mindre f¨ordr¨ojningarf¨orenheter i n¨atverken, exempelvis mobiler.
    [Show full text]
  • Integrated Optical Phased Arrays for Beam Forming and Steering
    applied sciences Review Integrated Optical Phased Arrays for Beam Forming and Steering Yongjun Guo 1,2, Yuhao Guo 1,2, Chunshu Li 1,2, Hao Zhang 1,2, Xiaoyan Zhou 1,2 and Lin Zhang 1,2,* 1 Key Laboratory of Opto-Electronics Information Technology of Ministry of Education, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China; [email protected] (Y.G.); [email protected] (Y.G.); [email protected] (C.L.); [email protected] (H.Z.); [email protected] (X.Z.) 2 Key Laboratory of Integrated Opto-Electronic Technologies and Devices in Tianjin, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China * Correspondence: [email protected] Abstract: Integrated optical phased arrays can be used for beam shaping and steering with a small footprint, lightweight, high mechanical stability, low price, and high-yield, benefiting from the mature CMOS-compatible fabrication. This paper reviews the development of integrated optical phased arrays in recent years. The principles, building blocks, and configurations of integrated optical phased arrays for beam forming and steering are presented. Various material platforms can be used to build integrated optical phased arrays, e.g., silicon photonics platforms, III/V platforms, and III–V/silicon hybrid platforms. Integrated optical phased arrays can be implemented in the visible, near-infrared, and mid-infrared spectral ranges. The main performance parameters, such as field of view, beamwidth, sidelobe suppression, modulation speed, power consumption, scalability, and so on, are discussed in detail. Some of the typical applications of integrated optical phased arrays, such as free-space communication, light detection and ranging, imaging, and biological sensing, are shown, with future perspectives provided at the end.
    [Show full text]
  • Satellite Earth Stations Validation, Maintenance & Repair
    Keysight Technologies Precision Validation, Maintenance and Repair of Satellite Earth Stations FieldFox Handheld Analyzers Application Note To assure maximum system uptime, routine maintenance and occasional troubleshooting and repair must be done quickly, accurately and in a variety of weather conditions. This application note describes breakthrough technologies that have transformed the way systems can be tested in the field while providing higher performance, improved accuracy, capability and frequency coverage to 50 GHz. A single FieldFox handheld analyzer will be shown to be an ideal test solution due to its high performance, broad capabilities, and lightweight portability, replacing traditional methods of having to transport multiple benchtop instruments to the earth station sites. 02 | Keysight | Precision Validation, Maintenance and Repair of Satellite Earth Stations Using FieldFox handheld analyzers - Application Note A satellite communications system is comprised of two segments, one operating in space and one op- erating on earth. Figure 1 shows a block diagram of the space and ground segments found in a typical satellite communications system. The space segment includes a diverse set of spacecraft technologies varying in operating frequency, coverage area and function. The satellite orbit is typically related to the application. For example, about half of the orbiting satellites operate in a Geostationary Earth Orbit (GEO) that maintains a fixed position above the earth’s equator. These GEO satellites provide Fixed Satellite Services (FSS) including broadcast television and radio. The location of GEO satellites result in limited coverage to the polar regions. For navigation systems requiring complete global coverage, constellations of satellites operate in a lower altitude, namely in the Medium Earth Orbit (MEO), that move around the earth in 2-24 hour orbits.
    [Show full text]
  • ANTENNA INTRODUCTION / BASICS Rules of Thumb
    ANTENNA INTRODUCTION / BASICS Rules of Thumb: 1. The Gain of an antenna with losses is given by: Where BW are the elev & az another is: 2 and N 4B0A 0 ' Efficiency beamwidths in degrees. G • Where For approximating an antenna pattern with: 2 A ' Physical aperture area ' X 0 8 G (1) A rectangle; X'41253,0 '0.7 ' BW BW typical 8 wavelength N 2 ' ' (2) An ellipsoid; X 52525,0typical 0.55 2. Gain of rectangular X-Band Aperture G = 1.4 LW Where: Length (L) and Width (W) are in cm 3. Gain of Circular X-Band Aperture 3 dB Beamwidth G = d20 Where: d = antenna diameter in cm 0 = aperture efficiency .5 power 4. Gain of an isotropic antenna radiating in a uniform spherical pattern is one (0 dB). .707 voltage 5. Antenna with a 20 degree beamwidth has a 20 dB gain. 6. 3 dB beamwidth is approximately equal to the angle from the peak of the power to Peak power Antenna the first null (see figure at right). to first null Radiation Pattern 708 7. Parabolic Antenna Beamwidth: BW ' d Where: BW = antenna beamwidth; 8 = wavelength; d = antenna diameter. The antenna equations which follow relate to Figure 1 as a typical antenna. In Figure 1, BWN is the azimuth beamwidth and BW2 is the elevation beamwidth. Beamwidth is normally measured at the half-power or -3 dB point of the main lobe unless otherwise specified. See Glossary. The gain or directivity of an antenna is the ratio of the radiation BWN BW2 intensity in a given direction to the radiation intensity averaged over Azimuth and Elevation Beamwidths all directions.
    [Show full text]
  • Planar Pattern Reconfigurable Antenna Integrated with a Wifi System for Multipath Mitigation and Sustained High Definition Video
    Planar Pattern Reconfigurable Antenna Integrated With a WiFi System for Multipath Mitigation and Sustained High Definition Video Networking in a Complex EM Environment Amit Mehta1, Shivam Gautam1, Hasanga Goonesinghe1, Arpan Pal1, Rob Lewis2 and Nathan Clow3 1College of Engineering, Swansea University, Swansea, U.K. [email protected] 2BAE Systems, Chelmsford, UK 3DSTL, Fort Halstead, UK Abstract—A planer pattern reconfigurable square loop antenna integrated in a complete wireless system is presented. II. ANTENNA CONFIGURATION The antenna is designed to operate at 5 GHz WiFi band of Fig. 1 shows the top and side view of the SLA designed IEEE 802.11 ac. The antenna under electronic switching for 5 GHz WiFi band. The Antenna structure is inspired generates four tilted beams in the four space quadrants. These four beams are moved intelligently and automatically in space from [4]. The SLA has four conducting arms, each of length using a C# program for achieving and sustaining maximum 32 mm and a track width of 1.5 mm. The square loop is possible throughput. This auto beam steering is advantageous etched on top of a Rogers 4350B (ɛr=3.66, tanδ=0.009) for scenarios where a mobile user suffers from multipath substrate having a thickness of 9.6 mm and an area of 60 fading in a complex electromagnetic environment. mm × 60 mm. The entire structure is backed by a metal ground plane. The SLA is excited at the center point of each I. INTRODUCTION arm (A, B, C and D) by four vertical probes of diameter 1.3 Indoor wireless communication in 5 the GHz WiFi band of mm which are connected to the four SMA ports (A0, B0, C0 IEEE 802.11 ac is becoming popular today due to the and D0) at the bottom of the antenna.
    [Show full text]
  • Error Analysis of Programmable Metasurfaces for Beam Steering Hamidreza Taghvaee, Albert Cabellos-Aparicio, Julius Georgiou, and Sergi Abadal
    1 Error Analysis of Programmable Metasurfaces for Beam Steering Hamidreza Taghvaee, Albert Cabellos-Aparicio, Julius Georgiou, and Sergi Abadal Abstract—Recent years have seen the emergence of pro- global or local reconfigurability [16]. Further, recent years grammable metasurfaces, where the user can modify the EM re- have seen the emergence of programmable metasurfaces, this sponse of the device via software. Adding reconfigurability to the is, metasurfaces that incorporate local tunability and digital already powerful EM capabilities of metasurfaces opens the door to novel cyber-physical systems with exciting applications in do- logic to easily reconfigure the EM behavior from the outside. mains such as holography, cloaking, or wireless communications. Two main approaches have been proposed for the im- This paradigm shift, however, comes with a non-trivial increase of plementation of programmable metasurfaces, namely, (i) by the complexity of the metasurfaces that will pose new reliability interfacing the tunable elements through an external Field- challenges stemming from the need to integrate tuning, control, Programmable Gate Array (FPGA) [17], [18], or (ii) by and communication resources to implement the programmability. While metasurfaces will become prone to failures, little is known integrating sensors, control units, and actuators within the about their tolerance to errors. To bridge this gap, this paper metasurface structure [19]–[22]. examines the reliability problem in programmable metamaterials Programmable metasurfaces have opened the door to dis- by proposing an error model and a general methodology for error ruptive paradigms such as Software-Defined Metamaterials analysis. To derive the error model, the causes and potential (SDMs) and Reconfigurable Intelligent Surfaces (RISs), lead- impact of faults are identified and discussed qualitatively.
    [Show full text]