Research On The Technique Of Reconfigurable Antenna For Satellite Communication

In this thesis,the technologies of wide beam,low elevation gain coverage,pattern reconfiguration and polarization reconfiguration of antennas are studied and applied in detail.The main work is divided into three aspects:1.According to the requirements of the low elevation gain for the low and medium earth orbit satellites,a four arms helical antenna working in S-band is designed.The simulation results show that its gain at low elevation is less than 0d B,and its performance is difficult to meet the gain requirements of low and medium orbit satellites at low elevation.In order to overcome the above problems,a circularly polarized planar helical antenna with conical mode radiation characteristics is studied,and the impedance matching of the antenna is adjusted by loading a ring sleeve.The simulation results show that the gain at the elevation angle of 10 ° is more than 3d B in the operating frequency band.2.In order to further improve the gain at low elevation,the designed antenna array is studied and further optimized.Firstly,in order to solve the low gain of antenna array at low elevation angle,this thesis uses meander technology to miniaturize the antenna to broaden the beam width of antenna,and overcomes the deterioration of element pattern in array by loading metal cavity around each array element.Secondly,the array antenna is fed by Wilkinson power divider and matrix switch to realize the reconfigurable radiation characteristics of the pattern.The simulation results show that in the working frequency band,the gain of the ring array antenna is greater than 8d B in the angle range of elevation from 10 ° to 90 °.Finally,the antenna is processed and tested,and the test results are in good agreement with the simulation results.3.The polarization reconfigurable technology is studied.According to the different polarization requirements of low and medium orbit satellite communication system,two Polarization Reconfigurable methods are used to design the relevant antenna respectively.Firstly,by changing the on and off state of PIN diode,the dipole antenna can switch between left-handed circular polarization and right-handed circular polarization,and introduce parasitic structure into the radiation plate to further broaden the beam width.The simulation results show that the VSWR is less than 2 and the gain is greater than 5d B in the frequency range of 2.24 ～ 3GHz.Secondly,a slot antenna loaded with Polarization Reconfigurable surface is proposed.By rotating the super surface,the radiation performance of linear polarization and double circular polarization can be obtained.The simulation results show that in the frequency range of 1.9 ～ 2.2GHz,the voltage standing wave ratio of the antenna is less than 2,the gain is greater than 7d B and the axial ratio is less than 3dB.