Research And Design Of Frequency And Patterns Hybrid Reconfigurable WLAN Antennas

In order to cope with the increasingly diverse communication needs and complex application environments,modern wireless communication systems are constantly moving toward high integration and intelligence.Therefore,it will become more and more difficult for the analog and fixed conventional antennas to meet the application needs.Reconfigurable antennas can change their radiation characteristics through changes in their own structures or feed networks and have high adaptability to changing needs and complex application environments,so that they can improve or even eliminate the performance limitations of traditional fixed antennas.Therefore,they have been widely studied by scholars at home and abroad.Based on the study and research of the basic theory of antennas and the key technologies of reconfigurable antennas,a frequency reconfigurable antenna and a frequency and pattern reconfigurable antenna are proposed in this thesis.Among them,the design of the frequency reconfigurable antenna adopts the idea of structural synthesis method,the inverted F antenna and the inverted L antenna are combined,and the antenna can be switched between three frequency modes by loading two PIN diodes and a complete coverage of the Wireless Local Area Network(WLAN)bands is realized.The design of the frequency and pattern hybrid reconfigurable antenna adopts the idea of multiple types of antennas fusion.Three basic types of antennas are fused by the loading of five sets of PIN diodes,finally,the antenna can be switched between seven states in three modes,so that the frequency and pattern reconfigurability can be realized and the WLAN band can be fully covered.In the design process,the antenna model is built by HFSS 13.0,a well-known highfrequency electromagnetic simulation software,and the main performance parameters of the antenna are simulated and analyzed.The simulation results show that the relative bandwidth of the frequency reconfigurable antenna in the WLAN 2.4GHz,5.2GHz,and 5.8GHz bands are 9.6%,14.1%,and 17.8%,respectively,and the maximum gains at the resonant frequency are 2.98 dBi,3.13 dBi,and 4.33 dBi,respectively.The antenna has good bandwidth,gain and impedance matching characteristics.The relative bandwidths of the frequency and pattern hybrid reconfigurable antenna in the WLAN 2.4GHz,5.2GHz,and 5.8GHz bands are 51.1%,7.3%,and 9.0%,respectively,and the maximum gains at the resonant frequency are 2.78 dBi,3.71 dBi,and 4.73 dBi,respectively.It has good bandwidth,gain and impedance matching characteristics,and can achieve large beam direction switching through the reconstruction of its pattern in both directional radiation modes.In this thesis,the antennas are also fabricated,and the return loss and voltage standing wave ratio of the fabricated antennas are tested by vector network analyzer.The measured and simulated results of the two antennas have high consistency.Therefore,the two reconfigurable antennas designed in this thesis can have certain application value in WLAN systems for different application scenarios.