Research Of Low-profile Circularly Polarized Antenna For Satellite Terminal

With the rapid development of satellite information system in China,as the"gate"for sending and receiving electromagnetic waves,the requirements for antennas are getting higher and higher.Circularly polarized antennas have low polarization mismatch loss and low multipath interference,which are usually used in satellite systems.Low-profile antennas can not only effectively solve the problem of smaller and smaller system space,but also are easy to mount and conform to more scenarios.Similarly,as a satellite terminal antenna,it must have wide beam and high gain at low elevation angle.The former expands the range of its receiving signal,and the latter can improve the receiving sensitivity of the entire system,which is suitable for multi-dimensional areas.Based on the application scenarios of satellite terminals,this article explores the properties of low profile,low elevation angle,high gain,and wide beam.Based on theory,three low profile and wide beam circularly polarized antennas,which are suitable for different scenarios,are designed and processed.The main work and innovations of this paper are as follows:1.Design a miniaturized circularly polarized satellite terminal antenna based on PIFA structure.PIFA is a linearly polarized antenna.The four PIFA arrays are circularly polarized in the far field through sequential rotating feeding,and the PIFA horizontal radiation patch is designed in the form of Archimedes spiral to make the antenna more compact.At the same time,a series-type one-to-four feeder network is designed for feeding.This antenna is suitable for most areas in China and can be used as a vehicle antenna.2.Design a low-profile circularly polarized satellite terminal antenna based on AMC structure.Design a gradual cross electric dipole to broaden the bandwidth of the antenna;add magnetic dipoles to broaden the antenna bandwidth while broadening the antenna's lobe width.In addition,a new AMC structure was designed to reduce the antenna profile by more than half and the principle was analyzed in detail.This antenna is suitable for most areas in China and can be used as a handheld and vehicle antenna.3.A low-profile circularly polarized satellite terminal antenna based on high-order mode is designed.The pattern formation mechanism and far-field pattern shape of the loop microstrip antenna are analyzed,and a low-profile antenna with a"hump"shape pattern is designed using the patternTM₂₁ as the working mode.A broadband Wilkinson power splitter is designed as the feed network to broaden the impedance bandwidth of the antenna.This antenna is suitable for high latitude areas in China.These several antennas designed in this article can be used in different scenarios.The radiation principle and formation mechanism of each antenna are analyzed,also simulation processing and experimental verification have been carried out.These antennas have simple structure,low profile,wide beam,low elevation angle and high gain,which are innovative and practical.