High-Efficiency Circularly Polarized Phased Array Based on 5 μm-Thick Nematic Liquid Crystals: Design, Over-The-Air Calibration, and Experimental Validation
Xin Yu Wu,
Fengshuo Wan,
Hongyuan Feng,
Shichao Jin,
Chong Guo,
Yu Wei,
Dunge Liu,
Yuqian Yang,
Longzhu Cai,
Zhi Hao Jiang,
Wei Hong
Affiliations
Xin Yu Wu
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Fengshuo Wan
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Hongyuan Feng
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Shichao Jin
State Key Laboratory of Space–Ground Integrated Information Technology, Beijing Institute of Satellite Information Engineering, Beijing 100095, China
Chong Guo
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China; Research Institute of Millimeter-Wave and Terahertz Technology (RIMMATT), Nanjing 211111, China
Yu Wei
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Dunge Liu
State Key Laboratory of Space–Ground Integrated Information Technology, Beijing Institute of Satellite Information Engineering, Beijing 100095, China
Yuqian Yang
State Key Laboratory of Space–Ground Integrated Information Technology, Beijing Institute of Satellite Information Engineering, Beijing 100095, China
Longzhu Cai
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China; Research Institute of Millimeter-Wave and Terahertz Technology (RIMMATT), Nanjing 211111, China
Zhi Hao Jiang
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China; Research Institute of Millimeter-Wave and Terahertz Technology (RIMMATT), Nanjing 211111, China; Corresponding author.
Wei Hong
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China; Research Institute of Millimeter-Wave and Terahertz Technology (RIMMATT), Nanjing 211111, China
This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquid-crystal-based phased array (LCPA), including the design, over-the-air (OTA) in-array calibration, and experimental validation. The LCPA contains 16 phase-shifting radiating channels, each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter (LCPS) based on a loaded differential line structure. Thanks to its slow-wave properties, the LCPS exhibits a maximum phase-shifting range of more than 360° with a figure of merit of 78.3(° )·dB−1 based on a liquid crystal layer with a thickness of only 5 μm. Furthermore, an automatic OTA calibration based on a state ergodic method is proposed, which enables the extraction of the phase–voltage curve of every individual LCPA channel. The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm, experimentally demonstrating a scanned circularly polarized beam from −40° to +40° with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB. The bandwidth of the LCPA, which satisfies the requirements of port reflection (|S11|) < −15 dB, an axial ratio (AR) < 3 dB, beam squinting < 3°, and a gain variation < 2.2 dB, spans from 25.5 to 26.0 GHz. The total efficiency is about 34%, which represents a new state of the art. The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams, along with the systematic design and calibration methodology, holds potential promise for a variety of millimeter-wave applications.
