Research On Fabry-Perot High Gain Antenna And Polarization Adjustable Technology

Compared with bulky horn antennas and traditional microstrip array antennas,the Fabry-Perot Cavity antenna(FPCA)has the advantages of high directivity,simple feeder network,and low cost.Therefore,FPCA have potential value in current or next-generation communications.On the other hand,because the polarized reconfigurable antenna has the characteristics of diversified functions,it can not only meet the requirements of the changeable and high rate of contemporary communication channels,but also improve the spectrum utilization and reduce the energy attenuation caused by the multipath effect.This paper studies broadband high-gain FPCA and polarization adjustable technology.1.This thesis analyzes the principle of FPCA,looks for the reasons for the narrow bandwidth of traditional FPCA,and finds ways to increase the gain bandwidth of FPCA.On this basis,a partially reflective surface(PRS)with a positive phase gradient was first designed.By adjusting the different parameters of the PRS unit,a positive gradient phase is achieved within 2.8-3.89 GHz.Secondly,a broadband feed antenna is designed with an impedance bandwidth of 32.4%(2.95-4.09 GHz).Finally,the PRS is combined with the feed antenna to form FPCA.The simulation results show that the impedance bandwidth is32.36%(2.9-4.02 GHz),the 1-d B gain bandwidth is 22.7%(2.96-3.73 GHz),and the peak gain is 14.02 d Bi.Compared with the feed antenna,the FPCA gain can be increased up to The maximum aperture efficiency is 42.7%.The FPCA has been processed and tested,the test results verify the correctness of the simulation results.2.In this paper,the polarization switching antenna is studied,and a polarization tunable resonator antenna that can realize three polarization switching is designed.First,a simple structure with a metasurface structure with polarization deflection capability is designed,and there is no need to load active controllable devices like general polarization reconfigurable antennas to avoid the effect of active device loss on gain.Secondly,a feed antenna with an impedance matching bandwidth of 24.1%(3.06-3.9 GHz)is designed.Finally,Finally,the metasurface structure and the feed antenna are combined,and the distance between them is determined according to the FPCA principle.By rotating the metasurface,the polarization conversion of the antenna can be realized.Among them,when the metasurface is rotated by90° or 270°,the antenna is left-handed circular polarization(LHCP).At this time,the impedance bandwidth is 22.9%(3.09-3.89 GHz),and the axial ratio(AR)bandwidth is15.4%(3.35-3.91 GHz);When the metasurface is rotated by 0° or 180°,the antenna is righthanded circular polarization(RHCP),the impedance bandwidth is 20.9 %(3.08-3.8 GHz),and the AR bandwidth is 8.3 %(3.56-3.87 GHz);When the metasurface is rotated by 135°,the antenna is linearly polarized(LP),the impedance bandwidth of the antenna at this time is 21.8 %(3.07-3.82 GHz),the maximum gain is 11.8 d Bi,and the 1-d B gain bandwidth at this time The width is 8 %(3.3-3.6 GHz).In addition,compared with the feed antenna,when working in linear polarization mode,the gain of this antenna during online polarization operation is increased by 1-2 d Bi.And the gain of the antenna is higher than 8 d Bic in circular polarization mode.3.This thesis takes the polarization principle of electromagnetic waves as the theoretical basis.We have designed two polarization converters with functions of polarization adjustable and frequency adjustable.In order to achieve the adjustable characteristics of polarization,a variable capacitance diode is introduced into the polarization converter.The first one is a double-sided pattern polarization converter,each side is loaded with two varactor diodes on the diagonal of the structure,and the capacitance value of the varactor diode in the polarization converter is controlled by controlling the DC bias voltage.The chemical converter can realize the conversion of LP-LP,LP-LHCP and LP-RHCP and the adjustable frequency within 3-4 GHz.The other is a double-sided quasiZ-type polarization converter,which has a simpler structure.By adjusting the capacitance value of the varactor diode loaded on the Z-type patch,the surface impedance of the converter changes and the transmission polarization is adjusted.The electric field of the converter changes and realizes the switching of three polarization modes and the adjustable frequency within 3-4 GHz.