Study And Design Of Reconfigurable Microstrip Antenna

Reconfigurable antenna can change its electrical parameters by adjusting the antenna structure dynamically.In the wireless communication system,the reconfigurable antenna can be used to reduce the number of the antennas,thereby decreasing the interference between communication systems and increasing the channel capacity of communication systems.This thesis presents the designs of a reconfigurable band-notch antenna,a frequency reconfigurable antenna and a frequency-pattern reconfigurable antenna.Reconfigurable characterizes of the antennas are achieved by introducing some PIN diodes and controlling the states of PIN diodes.The main research work are presented as follows.In chapter one,the background and significance of the reconfigurable antenna is firstly presented.Then,the relevant research status is introduced.In chapter two,a UWB monopole antenna with reconfigurable band-notch characteristics is presented.A stepped rectangle radiating patch is used to achieve ultra wideband operation.A slit is etched on the patch,and three switches are positioned in the slit.The reconfigurable band-notch capability of the antenna is achieved by changing the states of switches.The simulated and measured results show that the proposed antenna can operate at the UWB band and three reconfigurable notch bands.It covers the entire UWB band from 3.1 GHz to 10.6 GHz,with three reconfigurable notched bands 3.4-3.69 GHz,3.7-4.2 GHz and 5.2-5.875 GHz.In chapter three,a compact frequency reconfigurable slot antenna for LTE(2.3 GHz),AMT-fixed(4.5 GHz)and WLAN(5.8 GHz)applications is proposed.A U-shaped slot with short ends and two L-shaped slots with open ends are etched in the ground plane to realize dual-band operation.By inserting three PIN diodes inside the slots,three frequency bands can be achieved.Simulated and measured results show that the antenna can switch between two single-band modes(2.3 and 5.8 GHz)and two dual-band modes(2.3/4.5 and 4.5/5.8 GHz).In chapter four,a compact frequency and pattern reconfigurable slot antenna for TD-LTE(3.4-3.8 GHz)and C-band(3.7-4.2 GHz)applications is designed.The antenna consists of a fork-shaped feeding structure and a ground plane with two symmetric sickle-shaped slots.Two PIN diodes are placed in the connections of the horizontal and vertical arms of the fork-shaped feeding,the antenna can achieve pattern reconfigurability.Meanwhile,in order to achieve frequency reconfigurability,other two PIN diodes are inserted in the sickle-shaped slots.Simulated and measured results show that,at 3.4-3.8 GHz and 3.7-4.2 GHz,the antenna can switch its radiation patterns between an omni-directional mode and two directional modes,respectively.