Forum for Electromagnetic Research Methods and Application (FERMAT) Computational Electromagnetics Laboratory Wide Angle Scanning Planar Phased Array Antenna (Invited) Shaoqiu Xiao( 肖绍球 ), Yan Li( 李燕 ), Ren Wang( 王任 ), Youfeng Chen( 程友峰 ), Xiao Ding( 丁霄 ), Wei Shao( 邵维 ) and Bing-Zhong Wang( 王秉中 ) School of Physical Electronics University of Electronic Science and Technology of China, Chengdu 电子科技大学物理电子学院计算电磁学及其应用实验室 2017-08-03
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Abstract: Linear and 2-D phased arrays with wide-angle scanning are expected, especially for low elevation target searching. Many efforts have been done to enlarge the scanning range. There are several methods to broaden the scanning coverage of array. In this presentation, we only focus on enlarging the beam-width of elements to improve the wide-angle scanning performance of array. Pattern reconfigurable antenna, which increases beam-width equivalently, is used in a linear Vivaldi array for wide-angel scanning in time-domain. Element with Inherent wide beam is applied in linear and 2-D phased array to extend the scanning region. Key words: phased array; wide-angle scanning; linear and 2-D array
Biography: Shaoqiu Xiao received Ph.D. degree in Electromagnetic field and Microwave Technology from the University of Electronic Science and Technology of China (UESTC), Chengdu, China, in 2003. From January 2004 to June 2004, he joined UESTC as an assistant professor. From July 2004 to March 2006, he worked for the Wireless Communications Laboratory, National Institute of Information and Communications Technology of Japan (NICT), Singapore, as a Research Fellow with the focus on the planar antenna and smart antenna design and optimization. From July 2006 to June 2010, he worked for UESTC as an associate professor and now he is working for UESTC as a professor. He visited Ecole Normale Superieure de Cachan, Paris, France, as a senior research scholar in July 2015- August 2015. His current research interests include planar antenna and phased array, computational electromagnetics, microwave passive circuits and time reversal electromagnetics. He has authored/coauthored more than 260 technical journals, conference papers, books and book chapters.
Outline 1. Background and Motivation 2. Wide-Angle Scanning Array with Linear Array 3. Two-dimensional Wide-Angle Scanning Phased Array 4. Conclusions
Outline 1. Background and Motivation 2. Wide-Angle Scanning Array with Linear Array 3. Two-dimensional Wide-Angle Scanning Phased Array 4. Conclusions
Ship-based Satellite-borne Computational Electromagnetics Laboratory Planar phased array is applied extensively in civilian and military field. Ground-based Airborne
A Key Shortcoming and Challenges About Planar Phased Array: limited beam scanning range Non effective radiation range Beam scanning effective coverage range (conical surface) Non effective radiation range How to extend the effective coverage range of beam scanning?
Outline 1. Background 2. Wide-Angle Scanning Phased Array with Linear Array 3. Two-dimensional Wide-Angle Scanning Phased Array 4. Conclusions
Wide angle scanning phased array base on pattern reconfigurable antenna Rutern Loss(dB) 0-5 -10-15 -20-25 -30 Element state III state I state II -35 2.00E+009 2.10E+009 2.20E+009 2.30E+009 2.40E+009 2.50E+009 Frequency(GHz) Reflection coefficient Nomalized Radiation(dB) 0-2 -4-6 -8-10 -12-14 Fabrication state I state II state III -16-90 -60-30 0 30 60 90 Theta(deg) Radiation pattern State I: k1 and k2: on; k3 and k4: off; called R-mode State II: k1 and k2: off; k3 and k4: on; called L-mode State III: k1 and k2: off; k3 and k4: off; called B-mode
All elements in B-mode All elements in R-mode All elements in L-mode Realize wide angle scanning together By shifting states of the elements and adjusting the excitations of the elements, a good performance is achieved with 1 8 array: Scanning range: -60º ~ 60º ; Gain fluctuation: < 3 db ; Side lobe level: < -10dB
Linear array with time-domain antenna element Energy pattern reconfigurable element Mode P1 P2 1 on off 2 on on 3 off on In time domain, energy pattern is adopted to replace the radiation pattern in frequency domain. And the fidelity of the wave-form is also an important consideration. They are defined as follows: Energy pattern Fidelity
Performance of three reconfigurable modes Maximum direction of Mode-1: -45 Maximum direction of Mode-2: 0 Fidelity > 0.9 Maximum direction of Mode-3: +45
Using energy pattern reconfigurable element forms 1 8 linear array for beam scanning. The active VSWRs are lower than 2.2 on the frequency of 3.4~7.2GHz when scanning on the direction of -70º~+70º of the energy pattern.
The energy pattern can scan from -70º~+70º. When using Mode-1 on the scanning of -70º~-10º, Mode-2 on the scanning of -10~+10º,Mode-3 on the scanning of +10º~+ 70º.
The fidelities are all more than 0.9 on the scanning of the maximum radiation direction of the energy pattern.
Wide-angle scanning phased array based on image theory Image theory For low profile (planar) application, only JpM and MpE are suitable for wide angle converge of element because of specific boundary condition.
Example of MpE Wide-angle scanning phased array with magnetic dipole on metal plate Antenna element The loaded parasitic elements widen the radiation beam of the magnetic dipole. The 3dB beam coverage range is from - 75º 75º in the elevation plane.
8-element phased array with microstrip magnetic dipole elements Spacing between elements is 1/3λ 0. Strong coupling effect contributes to the broad beam coverage of the active element pattern of the array. The 3 db beam coverage range of the active element pattern is over ±80
Fabricated and measured photograph Simulated scanning pattern The measured and simulated results indicate that the array can scan its main beam from - 78 ~79 with a maximum gain of 15.2dBi and a minimum gain of 12.9dBi over the entire scanning range. Measured scanning pattern
Example of JpM Wide-angle scanning phased array with electric dipole on artificial magnetic wall The periodic metal structure printed on grounded substrate has a reflection phase of 0 o at 5.8GHz, which means the surface can be regarded as an artificial magnetic wall.
Antenna element is formed by a metal strip placed on the designed artificial magnetic wall Radiation beam in E-plane is extended as the increasing of periodic structure number.
Array prototype Comparison of end-fire patterns of different array Beam scanning performance of proposed array The results indicate that the array can scan its main beam from -90 ~90 with a maximum gain of 15dBi with fluctuation of 3dB over the entire scanning range.
Outline 1. Background 2. Wide-Angle Scanning Array with Linear Array 3. Two-dimensional Wide-Angle Scanning Phased Array 4. Conclusions
Although the linear array can scans its main beam within wide angle range, there are huge challenge to realize twodimensional wide-angle scanning for planar phased array Directivity(N*N=16*16) 1 0.8 0.6 0.4 0.2 d/lam=0.3 d/lam=0.4 d/lam=0.5 d/lam=0.6 d/lam=0.7 Directivity of the array factor decline when the scanning angle of phased array increase. The ideal aperture efficiency is close to cos(θ 0 ). This characteristic is unfavorable for wide angle scanning 0 0 0.5 1 1.5 30 thetax 0 60 90
Disadvantage: high profile (about 2~3 wavelength at highest operation frequency) and space range of beam scanning not so wide Computational Electromagnetics Laboratory Low profile Vivaldi array for wide angle scanning application All-metal Vivaldi antenna has been used extensively in wide band phased array Wide band phased array with All-metal Vivaldi antenna
An all-metal Vivaldi antenna made of stainless steel with coaxial feed and a copper floor is designed. The element width is selected to be 12mm (0.48*λ 0 ) and the profile is only 9.4mm (0.376*λ 0 ), where λ 0 is the wavelength corresponding to the highest operating frequency in free space.
The frequency band range of the element is 7.2GHz-12GHz H-plane patterns are almost all omnidirectional patterns E-plane HPBWs: 150 o (8GHz) 186 o (10GHz) 202 o (12GHz)
1 8 linear array with E-plane coupling Element distance : 13.5mm Gains: 8.68dBi(8GHz) 11.98dBi(10GHz) 12.16dBi(12GHz)
1 8 linear array with H-plane coupling Element distance : 12mm Gains: 9.33dBi(8GHz) 10.40dBi(10GHz) 11.30dBi(12GHz)
8 8 all-metal Vivaldi array with triangular lattice structure
When the array scans from broadside to 56 О, the gain decline 3dB at 10GHz However, the active S parameters is so bad
8 8 all-metal Vivaldi array with triangular lattice structure and absorber
When the array scans from broadside to 56 О, the gain decline 3dB at 10GHz However, the active S parameters are also improved remarkably.
2-D Planar Wide-Angle Scanning Phased Array Based on Wide-Beam Elements Element structure design The parasitic pixel surface is able to induce significant currents due to the strong coupling between the driven antenna and the parasitic surface. Driven antenna Pixel surface
The measured HPBWs of the antenna are 188 and 156 in the two planes. The simulated and measured peak gains are 2.86 and 2.12 dbi, respectively.
0.42 λ 0 0.43 λ 0
Array supports a wide-angle scanning from 75 to 78 along the xoz-plane, and 75 to 77 along the yoz-plane, respectively.
Outline 1. Background 2. Wide-Angle Scanning Array with Linear Array 3. Two-dimensional Wide-Angle Scanning Phased Array 4. Conclusions
Conclusions: The background of researches on wide angle scanning phased array is introduced Two kinds of methods have been proposed to realize wide angle scanning for linear array. Two examples of planar phased array for twodimensional wide angle scanning have been demonstrated
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2018 Microwave Week 2018 微波周 May 7-11, 2018, Chengdu, China 5 月 7 日 11 日, 成都 2018 Int. Conf. on Microwave and Millimeter Wave Tech. (ICMMT 2018) 2018 年国际微波毫米波技术会议 2018 年全国微波毫米波会议 (NCMMW 2018)
Prof. Shaoqiu Xiao Email: xiaoshaoqiu@uestc.edu.cn