A Patch Circularly Polarized Antenna Based On Filtering Phase-shifting Power Division Feeding

Nowadays,with the development of the technology,people have put forward stricter requirements for information transmission,which brings more opportunities and greater challenges to mobile communications.At present,there are many studies on filtering antennas and circularly polarized antennas,but the researches on filtering circularly polarized antennas are insufficient.This thesis mainly conducts a series of researches on the filtering circularly polarized antennas and designs a patch circularly polarized antenna based on filtering phase-shifting power division feeding.The design of the filtering circularly polarized antenna is inctrduced in detail.The antenna are studied as follows:1.A third-order hairpin filter with a center frequency of 2.4 GHz is designed.Based on the hairpin filter,a phase shifter with a phase-shift of 90°is studied.During the operating frequency band of 180MHz,the S₂₁ is above-1d B,the S₁₁ is below-25d B and the phase-shift is 90°±2°.2.The Wilkinson power divider is used to connect the phase shifter to realize a power divider filter feeding network.The operating bandwidth is 210MHz?2.29GHz-2.51GHz?.In the operating band,the S₁₁ is below-22d B and the phase-shift is 90°±3°.3.A filtering circularly polarized antenna is designed.The patch is elevated with air as the medium to increase the bandwidth of it.The impedance bandwidth of 2.24GHz-2.5GHz is wide.The gain of the antenna is very smooth during the band,and the maximum is 6.1d B.Outside the high-frequency operating band?2.5GHz-2.7GHz?,the gain is less than-10d B.With-3d B as the standard,the axial ratio bandwidth is 2.24GHz-2.5GHz,which is consistent with the impedance bandwidth.The axial ratio is also smooth in the frequency band.This antenna has good circular polarization characteristics.