The Research And Design Of Polarization Reconfigurable Antenna

In recent years,with the continuous development of communication systems,reconfigurable antennas have become a hot topic in the field of antenna research.A large number of new design methods and antenna models are constantly emerging.Such an antenna can change its operating frequency,radiation pattern,polarization mode,and input impedance and other characteristic parameters without changing its mechanical structure by a non-mechanical means.It is called an electrically controlled reconfigurable antenna.The electrically controllable reconfigurable antenna mainly achieves switching of the working mode by controlling the radiation structure of the antenna by using a PIN diode switch or an RF MEMS switch.The polarization reconfigurable antenna is a kind of electronically controlled reconfigurable antenna.It can increase the independent transmission and reception channels without increasing the antenna volume,and is particularly suitable for mobile communication terminals with limited size.In addition,the polarization reconfigurable antenna can achieve frequency reuse,eliminate multi-path fading in the communication system,and improve the performance of the communication system and the remote sensing system by controlling the polarization state.The application of polarized reconfigurable antennas has broad application prospects,from commercial applications to military applications,especially in the rapidly developing field of wireless communications and navigation.This paper designs two antennas that can be used in wireless communication systems.One is a left-hand circularly polarized antenna based on a ring gap and the other is a reconfigurable antenna.1.A left-hand circularly polarized antenna based on an annular gap achieve circularly polarized radiation by etching the annular gap at a suitable location on the ground plane.The center frequency of the antenna is 2.45 GHz,operating in the 2.4-2.5 GHz band.The impedance coefficient S11 of the antenna at the center frequency is less than-15 dB.The impedance bandwidth of S11 less than-10 dB is approximately 100 MHz,and the axial ratio AR at the resonance frequency is approximately 0.76dB.The bandwidth of AR less than 3dB is about 60MHz,and the maximum gain of the antenna is 5.7dB.The antenna performance is good and meets the design specifications.2.The polarization reconfigurable antenna is based on a left-hand circularly polarized antenna and is modified(by loading a MEMS switch at a suitable position in the slot)to achieve linear to circular polarization,left-hand circular polarization to right-hand circular polarization conversion.The advantage of this design is that it does not need to add extra perturbation units,nor does it need to design a complicated bias network.By adjusting the position of the slit and the switching of the switch,the conversion between linear polarization,left circular polarization and right circular polarization can be achieved.The center frequency of the antenna is 2.45 GHz,and the left-hand circular polarization can be converted to right-hand circular polarization at the center frequency.The axial ratios of the left-hand circular polarization and the right-hand circular polarization are 0.76 dB and 1.45 dB,respectively.The bandwidth is about 60MHz and the impedance bandwidth is about 100MHz.The antenna gains is 5.7 dB and 5.5 dB in left circular polarization and right circular polarization,respectively.It meet the design requirements.The left-circular polarized antenna and the polarized reconfigurable antenna designed in this paper are simulated by the electromagnetic simulation software HFSS 15.0.The performance of the antenna is stable and the desired effect is achieved.