Research On Pattern Reconfigurable Microstrip Antenna For 5G

Entering 5G era,wireless communication technology has been greatly improved,and more and more 5G user groups make the communication environment increasingly complex,and the system has higher and higher requirements for antenna performance.Large-capacity,multi-function,and ultra-wideband are important directions for the development of wireless communications.In order to increase system capacity,researchers have proposed the use of Multiple-input-multiple-output(MIMO)technology to improve spectrum utilization.However,as the number of antennas used increases,the overall cost of the communication system and the weight also increases,there will be problems in electromagnetic compatibility.Reconfigurable antennas came into being under this background.In the communication system,the antenna is a device that receives and launch electromagnetic waves and plays a key role.Compared with ordinary antennas,reconfigurable antennas have the function of multiple antennas.However,the realization of reconfigurable antennas needs to excite multiple modes,and design a very suitable feed network so that modes can be switched freely.This is the focus and difficulty of reconfigurable antenna.Aiming at this difficulty,this paper loads shorting pins and slits on the circular microstrip antenna,uses PIN diodes to design the feed network to realize the design of pattern reconfigurable microstrip antenna,and uses the superposition of patterns to realize the azimuth plane pattern reconfigurable antenna design.The main work and innovation of this paper are as follows:(1)A bidirectional beam reconfigurable microstrip antenna based on Characteristic Mode Theory is proposed.On the basis of microstrip antenna,the circular patch is loaded with 7 shorting pins,and switching between two orthogonal bidirectional beams and four beams can be realized by controlling four PIN diodes.The Characteristic Mode Analysis provides the physical mechanism of antenna's work,and provides an appropriate feeding method for exciting each mode separately.The maximum gains of the two orthogonal bidirectional vertically polarized beams at 3.4 GHz are 6.8 and7.3d Bi.When all the diodes are in the on state,they are combined into a four-beam mode.The bidirectional reconfigurable microstrip antenna was processed and tested in a darkroom to verify effectiveness of the antenna design.(2)A azimuth-pattern reconfigurable microstrip antenna based on Characteristic Mode Theory is proposed.On the basis of circular microstrip antenna,a rectangular slot is opened in the vertical direction of the patch,and a row of shorting pins are loaded under the patch in the horizontal direction.With the help of characteristic mode analysis,the integration of different current modes can achieve mode reconfiguration.By controlling different feed ports,four controllable beams can cover the entire azimuth plane.The antenna was processed and tested,and the measured front-to-back ratio was close to 10 d B at 2.08 GHz,and the 3d B beam width on the azimuth plane could be switched from 82°(181°)to 190°(91°).(3)A beam switchable microstrip antenna based on Characteristic Mode Theory is proposed.On the basis of the circular microstrip antenna,four rectangular slots are opened on the patch,and five shorting pins are loaded in the horizontal direction.With the help of characteristic mode analysis,it can provide help for the excitation of each mode.The designed feed network can pass control ON/OFF of the PIN diodes to switch freely between the three modes.After simulation,two orthogonal bidirectional patterns appear near 3.25 GHz,and a broadside pattern.The gains of the three patterns are 3.3,4.5,and 5.3 d Bi respectively.