Design Of Several Wide Beam Beidou Navigation Antennas

In recent years,Chinese Beidou satellite navigation system has been rapidly developed and also gradually put into use.Circularly polarized wave can eliminate multipath effects and overcome Faraday rotation,so circularly polarized antennas are very suitable for Beidou satellite navigation system.The antenna with wide beamwidths can be used to receive more satellite signals,thereby stability of the Beidou satellite navigation system can be improved.Therefore,the wide-beam circularly polarized antenna for the Beidou navigation system is an important topic.In this thesis,the Beidou navigation antenna is our research aim.Based on the circularly polarized microstrip antenna,the design method for the Beidou navigation antenna with wide beamwidths is mainly studied.Two Beidou navigation antennas with wide beamwidths are presented.The main research work of this thesis can be summarized as follows:1.A Beidou navigation antenna?with wide beamwidths is designed.The conductor walls shorted to the floor are loaded around the circularly polarized microstrip antenna to broaden the antenna beamwidths and cut off the weaker portions of the conductor walls to increase antenna efficiency.The designed antenna with wide beamwidths has good circular polarized characteristic.Simulated results show that the 3dB axial ratio bandwidth of the antenna covers the Beidou B1 band(1561MHz?8MHz).At the center frequency(1.561GHz),the half-power beamwidths in E and H planes of the antenna are 112~?(7)-57~?(25)55~?(8)and111~?(7)-57~?(25)54~?(8)respectively.The beamwidth of the designed antenna is extended more than 42%than the circularly polarized microstrip antenna.According the simulated model,the Beidou navigation antenna?with wide beamwidths is fabricated and measured.The measured results are in good agreement with the simulated results.2.A Beidou navigation antenna?with wide beamwidths based on the parasitic structure is designed.Loading the parasitic ring antenna and the parasitic monopole array can broaden the beamwidths of the circularly polarized microstrip antenna.Simulated results show that the 3dB axial ratio bandwidth of the antenna covers the Beidou B1 band(1561MHz?8MHz).At the center frequency(1.561GHz),the half-power beamwidths in E and H planes in antenna are 127~?(7)-65~?(25)62~?(8)and 127~?(7)-62~?(25)65~?(8)respectively.The gains of the designed antenna are greater than-1.5dBic when the elevation angle is larger than 10~?.The simulated antenna efficiency is about 83%.According the simulated model,the Beidou navigation antenna?with wide beamwidths based on parasitic structure is fabricated and measured.The measured results are in good agreement with the simulated results.