Research And Design On Optically Controlled Frequency-reconfigurable Antenna

With the capability to dynamically change their radiation characteristics,reconfigurable antennas will become indispensable parts for the RF front-ends of the next-generation wireless communications.In this dissertation,optically controlled microwave switch(OCMS)and it's applications in reconfigurable antenna have been investigated in this thesis,and several design schemes of optically controlled frequency-reconfigurable antennas are presented.The specific content and work of this paper contains:1.The key factors affecting the performance of OCMS are analyzed based on the stratified plasma layer model based on OCMS.A kind of sink structure was designed to improve the insertion loss of the OCMS.The OCMS was tested.The equivalent conductivity of the plasma layer was extracted by the test results,which laid a foundation for the design of the optically controlled frequency-reconfigurable antenna.2.In the design of optically controlled frequency-reconfigurable monopole antenna,by controlling two OCMSes with the laser to change the antenna's resonant frequency.The antenna can operate at different frequencies with three cases.These three operating bands can cover some practical wireless communication applications,such as GSM(1.8GHz),WLAN(2.4GHz,5.5GHz).3.A compact novel CPW-fed frequency-reconfigurable antenna is designed and fabricated.The dimension of the antenna is 14×12.6×1.0mm~3.The frequency-tunable characteristic of antenna can be obtained by adding two OCMSes.The antenna can operate at different frequencies with three cases.By controlling two OCMSes with the laser,two appropriatelyplaced laser-controlled photoconductive silicon switches are used to achieve reconfigurable frequency characteristics in the three bands of 3.2-5.0,5.0-7.0 and 8.3-8.8GHz with the reflection coefficient below-10 dB.4.A novel optically controlled frequency-reconfigurable microstrip antenna with completely switchable frequency bands has been presented.The dimension of the antenna is40×40×1.6mm~3.The antenna uses a switchable slotted structure on the ground plane to deliver the reconfigurable capability.The proposed antenna is simple to design and fabricate and exploits four OCMSes to switch on the desired frequency bands.The antenna is able to operate at five different switching states with a reasonable return loss.By controlling four OCMSes with the laser and a four-way splitter,the antenna can be tuned to cover a ultra-wideband(2.3-7.6GHz),three narrower operating bands(2-2.7GHz,5.0-6.5GHz and 1.8-2.8 GHz)and dual-band(1.8-3.2GHz and5.0-6.2GHz).