Space-Efficient UWB 2-D and 3- D antenna elements. Anatoliy Boryssenko* and Elen Boryssenko A&E Partnership, Belchertown, MA, USA

Transcription

1 Space-Efficient UWB 2-D and 3- D antenna elements Anatoliy Boryssenko* and Elen Boryssenko A&E Partnership, Belchertown, MA, USA 1

2 Outline Background and Motivations Attempt of Design Systematization Case Study 1: 2-D UWB Antenna Case Study 2: 3-D UWB Antenna Case Study 3: Omnidirectional UWB Antenna Summary Questions Methodology Practical Design Illustrations 2

3 Application Areas 1. UWB Telecommunication: license-free short range radios, boomed at the beginning of the 2000s and quite decayed so far; range extender; RFID; MIMO arrays; stealth comm.; SDR; 2. UWB Sensing and Imaging Applications: detection of landmines, UXOs, IEDs; through-the-wall vision; full in-body scanner; biomedical applications; UAV antennas and arrays (SAR imaging, SIGINT); 2. Biomedical Applications: imaging (tumors, hematomas, external objects (surgery leftover ); cardio-vascular monitoring; blood circulation; others 3. High-Power Electromagnetics (HPEM): IED neutralization, atmosphere pressure industrial plasma; focused hyperthermia 4. Test Equipment 5. Likely Others 3

4 Major Design Specifications to Deal With Impedance/Gain Bandwidth: typically Max Frequency : Min Frequency Terminal: at given reference level, e.g. S11=10dB Radiation: radiations in designated directions Efficiency: Pout/Pinp as high as possible, sometimes compromised to trade for lower Min Frequency Polarization: typically linear, purity is not of major concern unless particular required Additional Others: spectral masks, pattern shapes, etc. Size, Weight and Cost: application specific, driven by electrical specs 4

5 Required vs. Realizable Dimensions Design Specifications Bandwidth Size Constraints Design Process Methods/Tools Examples/Experience Intuition/Heuristics Innovation/Invention Physics Realizable Dimensions How these two could be close? Space using efficiency: ratios of linear dimensions in XYZ with respect to the lowest operational frequency; they should be <0.5λ Prior theoretical and numerical studies are mainly for CW Some extensions for UWB do not supply with explicit guidelines, design rules, etc. 5

6 Outline Background & Motivation Some Attempt of Design Systematization Case Study 1: 2-D UWB Antenna Case Study 2: 3-D UWB Antenna Case Study 3: Omnidirectional UWB Antenna Summary Questions 6

7 Search in UWB Antenna Literature Some Google Images 7

8 How to Navigate in this Vast Realm? A metaphorical view on UWB Antenna Chaos Taxonomical and Heuristic Studies on UWB Antenna Design Strategies, High Frequency Electronics, August

9 Shape Variations to Broaden Resonances and Increase Impedance Bandwidth Monopole Conductor Extrusion BOR 2-D to 3-D Rolling Taxonomical and Heuristic Studies on UWB Antenna Design Strategies, High Frequency Electronics, August

10 Shape Variations to Increase Radiation Gain Bandwidth and Magnitude Bow-tie Dipole to Vivaldi Backing with Reflector Bow-tie Dipole to TEM-horn Taxonomical and Heuristic Studies on UWB Antenna Design Strategies, High Frequency Electronics, August

11 Topological and Metric Relations Topological Similarities Bandwidth versus Size Principal Dimensions to Define Lowest Operational Frequency 11

12 Outline Background & Motivation Attempt of Design Systematization Case Study 1: 2-D UWB Antenna Case Study 2: 3-D UWB Antenna Case Study 3: Omnidirectional UWB Antenna Summary Questions GHz Bandwidth Gain monotonic >2dB Operate with and without GRND 12

13 Parametric Tuning & Physical Phenomenology 50 Ω 120π Ω Antipodal Vivaldi Antenna (AVA) Some representative cross-sections Two-sided slot Asymmetrical Strip Line Symmetrical Strip Line Microstrip 13

14 Parametric Modeling of Shapes Coded in this script lines 14

15 Variety of Antenna Conductor Shapes We need to cover all such possible shapes: 1) Parametric geometrical model 2) Modeling tool in Matlab 3) CAD inputs for CEM solvers 15

16 Not-Optimal Antenna Major Scattering Events in CST 16

17 Nearly-Optimal Antenna Major Scattering Events in CST 17

18 TD and FD Pictures of Scattering Events Not Optimal Nearly Optimal 18

19 Ground Plane Impact 0.55 GHz 0.85 GHz 2.00 GHz Unwanted! 3.00 GHz Unwanted! 4.00 GHz 19

20 Catastrophic Pattern Distortions Very band! Very band! Exploring the surface current distributions helps often to realize what is going wrong Pattern problems are not necessary related to bad impedance mismatching 20

21 Terminal Features Simulated Measured 21

22 Radiation Pattern Examples for Final Design Resulted from iterative design optimizations Freq, GHz W/o GRND, db W/ GRND, db Realized gain is monotonically increased from 2 dbi (3dBi with ground plane) at 0.5 GHz up to 8 dbi at 7 GHz 22

23 A bit More Bandwidth w/o Extra Space Introducing Additional Delays and Longer Transitions Equivalent Straight Signal Path from the Feed Point To the Aperture Opening A wider bandwidth might be expected from this spacesaving layout 23

24 Simulated vs. Measured S11 Simulated Measured HFSS Model Physical Structure Built 24

25 How Space Efficient Our Designs Are? TYPICAL 107x74 mm, 20-mil Rogers RO4003 ONE of BESTs 52x57 mm, 60-mil Rogers RO x0.67 λmax 0.47x0.52 λmax OURS: 0.33x0.27 λmax 0.30x0.30 MHz 0.15 λmax difference is 3 inch 0.50 λmax difference is 1 feet 25

26 One More Comparison vs. Commercial 3-D ETS Lindgren GHz 4.0 lb 9.6 x 11 x 6 in This coffee-maker cartoon box has its overall Cost $5k (2009) with 4-week delivery dimensions ±1 inch close to ETS Lindgren mil FR4 Weight ¼ lb 26

27 Outline Background & Motivation Attempt of Design Systematization Case Study 1: 2-D UWB Antenna Case Study 2: 3-D UWB Antenna Case Study 3: omnidirectional UWB Antenna Summary Questions 27

28 Design Evolution: from 2-D to 3-D 28

29 Folded TEM Horn: Tongue Element Flare Profiles Polygon CAD Model Prototype 29

30 Typical Input Impedance GHz Operational Band Predicted Input Impedance MoM Mesh Dimensions: 8 high 4 wide 2 deep Parametrically optimized to support 50-Ω input resistance & nearly 0-Ω input reactance 30

31 DIY UWB Compact UWB Antenna Dimensions: (w/o supporting foam) 3 high 3 wide 1 deep 2-8 GHz Operational Band 31

32 Simulated Radiation Patterns GHz GHz E-plane H-plane Good gain and front-to-back ratio! 32

33 Simulated vs. Measured Patterns 3 GHz 4 GHz 5 GHz 6 GHz E H Solid simulated Dashed - measured 33

34 3-Element Array (One Tx & Two Rx) Aperture side view Backside view Control PCB Tongue Radiator Tripod Tuning Element Tx PCB Left Rx PCB 34

35 Folded TEM Horn UWB Reflector Feed 2-18 GHz Operational Band Dimensions: 2 high 2 wide 3 deep Input Impedance Tends to nearly 50 Ohm Resistance & 0 Ohm Reactance 35

36 Simulated Radiation Patterns 2-18 GHz Operational Band 36

37 Outline Background & Motivation Attempt of Design Systematization Case Study 1: 2-D UWB Antenna Case Study 2: 3-D UWB Antenna Case Study 3: Omnidirectional UWB Antenna Summary Questions 37

38 Distributed Lumped RLC Loading Design Concept Computer Model Prototype Design Technique: Numerical ElectroMagnegnetic Optimizer (NEMO) It is only one way to tune such antennas otherwise brute-force try-and-error is inefficient E.g. tuning one R or L or is completely counterintuitive 38

39 Impedance Bandwidth Input Impedance (Simulated) VSWR (Measured) W/o lumped RLC W/ lumped RLC Positive gain bandwidth Cab be tunable as for SDR 39

40 Radiation Pattern Radiation Pattern Regular Monopole RLC Loaded Monopole Note the effect of finite ground is tolerated also 40

41 Summary Tried to demonstrate a systemized approach to design 2-D and 3-D space-efficient UWB antennas Illustrated this methodology by three examples of practical directional and omnidirectional designs Omitted some important steps such as simulations and parametric optimization using commercial and home-made CEM tools Designed, built and tested successfully several broadband multi-octave phased arrays by employing somewhat similar methodology 41

42 Thank You! Questions? 42