Research On Circular Polarized Antenna For Vehicle-borne Satellite Communication

In recent years,the development of satellite communication technology has been changing with each passing day.With the popularization of automobiles,the application of in-vehicle satellite communication has become more and more widespread,and people have put forward higher requirements for in-vehicle satellite communication services.As the basis of in-vehicle satellite communication,research on in-vehicle satellite communication antennas is particularly indispensable.This paper focuses on existing bandwidth and miniaturization of the vehicle satellite communication antennas.Some of the research results have been published in well-known foreign journals in this field.The main research work of this paper is as follows:.1.In view of the fact that most of the satellite communication antennas are circularly polarized antennas,a broadband single-feed antenna with a single parasitic patch is proposed,which comprises a four-sided metal wall and an irregular metal floor.Thus,the axis of the antenna is adjusted.The specific gain of the antenna is also achieved.The cross dipole arm adopts a novel form of semi-ellipse and rectangular arm combination,which produces two adjacent axial ratio passbands that greatly broadens the bandwidth of the antenna.The measured relative axial ratio of the antenna is 71.8%(2.3GHz-4.85GHz),the average gain is 9dB,and within the passband,the flat of the gain is less than 2dB.2.Considering the uncertainty of the satellite communication during the driving process,it is necessary to miniaturize the antenna.Achieving high antenna gain and wide-angle circular polarization are also very important.Therefore,a 2×2 small printed antenna array is designed.The antenna unit is composed of four inverted L antennas,which is fed by an equal amplitude phase difference power splitter,so that the antenna radiates circularly polarized waves externally.It can be seen from the results that the gain of the antenna unit(0.25?×0.25?×0.05?,? is the center frequency 1.48GHz)is about 3.8dB,and the gain of the 2×2 antenna array is about 7.6dB.In addition,the small array also has some scannability by introducing a feed network consisting of a 3dB directional coupler.3.Based on the wide application of Ku-band in satellite communication systems,the research on the carrier-satellite communication antenna in Ku-band is also increasing.In order to reduce the cross polarization of the antenna and the interference it receives,the design of carrier-satellite communication circular polarization antennas is particularly important.Thus,a wide-band small circularly polarized antenna with cascade metal cavity is designed.The simulation results show that the antenna has a standing wave bandwidth of 6.6-17.8 GHz and an axial ratio bandwidth of 11.8-17.7 GHz.At the same time,in order to achieve low profile,a 2×2 low profile microstrip antenna array based on SIW feed is designed.The height of the antenna array is only 1.408mm(0.056?),and the gain of the antenna array is 13dB.