Design Of Polarization Reconfigurable Antenna Array Based On Mode Combination Method

Polarization reconfigurable antenna has extensive applications in wireless communications,microwave imaging,and some other fields.Based on the theory of mode combination method,two polarization reconfigurable array antennas and a linear polarization reconfigurable antenna with arbitrary polarization azimuth angle were proposed.The three models were measured and the results are in good agreement with the simulation.The main work of this paper is given as follows:1.A polarization reconfigurable 2x2 array antenna based on a switchable feeding network is proposed,which can realize left-handed circular polarization(LCP)and right-hand circular polarization(RCP)and two linear polarization modes(LP1 and LP2).The main work includes designing a 1 minute 8 reconfigurable feeding network to switch the polarization states through DC bias-voltage.The measurement results show that the proposed antenna has an overlapping 10 dB impedance bandwidth of about 34% for the CP mode and the LP(2)mode,and the overlapped 3 dB axis ratio bandwidth is about 22.0% of the CP mode.For CP mode and LP(1)mode,the average realized gain is approximately 12.4 dB,which is stable over the axial ratio bandwidth.2.A polarization reconfigurable 2x2 array antenna based on reconfigurable antenna element is proposed,which can realize left-hand circular polarization and right-hand circular polarization and linear polarization switching.Two PIN diodes are implanted on the antenna radiator,and the working state of the radiant body is changed by adding a DC voltage to control the working state of the PIN diode,so that the polarization of the unit can be reconstructed,and the array LP mode is formed by the combination of the unit CP modes.Measurement results show that the proposed antenna has an overlapped 10 dB impedance bandwidth of around 11.2% for both CP modes and the LP one.The realized maximum gains are around 7.5dB for the CP modes and 5.6dB for the LP mode.3.A linear polarization azimuth angle adjustable antenna is proposed.Based on the theory of circular polarization mode combination,the antenna can achieve linearly polarized radiation at any azimuth angle of 360 degrees on the horizontal plane.In order to verify thetheory of mode combination,a dual-mode antenna was designed,and the linearly polarized radiation in the 135°,180°,225° and 270° directions was realized by controlling the initial phase of the fundamental modes.The simulation and measured results show that the 10 dB impedance bandwidth and gain of the antenna working in different linear polarization directions remain relatively stable.