| With the continuous development of modern mobile communication technology,antennas,as an indispensable part of wireless communication systems,are also moving rapidly in the direction of multi-function,integration and miniaturization.More and more researchers are beginning to explore antenna-related technologies in order to promote antenna research towards the era of miniaturization and integration.In the work of the communication system,the antenna generally transmits and receives the signal,and then the filter filters the signal,and finally the signal can be identified or used.These two parts are often designed separately and used cascaded by transmission lines.Then the size of the two,their respective radiation efficiency,filtering effect and whether the impedance between the two matches,will seriously affect the performance of the entire communication system.Some filter antennas require additional filtering circuitry to ensure communication quality,but this adds additional losses and reduces antenna gain.At this time,a filter antenna that can simultaneously radiate and filter,with excellent overall performance,simple structure and anti-interference has attracted widespread attention.Pattern reconfigurability technology can change the shape of the pattern or the radiation direction of the main beam without changing the polarization mode and operating frequency of the antenna.Therefore,this paper has done relevant research work on the design of the above high-performance antennas,and the main research content is roughly as follows:Firstly,the background and significance of differential filtering antenna applications are pointed out,and the research status of this field in China and abroad is summarized.In addition,the remaining problems and technical challenges are analyzed.Then,in view of the problems discovered above and have been existing,the design method of differential dualpolarization antenna with filtering function is explored.The designed antenna has a strict symmetrical structure and uses differential feeding.Without adding extra filter circuits,good filtering characteristics are achieved while ensuring the effect of external radiation of the antenna.The final antenna exhibits good radiation direction characteristics while also having low cross-polarization and high port isolation.And the antennas are formed into an array to improve the gain and enhance the ability to receive and radiate the signal.Finally,the reconfigurable effect of differential antenna pattern is analyzed,and the reconstruction effect of antenna pattern is achieved by loading guides on both sides of the antenna.The details are as follows:(1)Two differential feed filter antennas are proposed.The antenna consists of a double-layer parasitic patch,a drive patch,a ground slot and a feed structure.The differential signal passes through the feed network and couples to the drive patch through a coupling slot on the ground,thereby driving the two parasitic patches to radiate outward.Based on this 2-port antenna,a second 4-port differential filtered dual-polarized antenna is designed.By using two identical pairs of differential feeders to excite the proposed antenna,advantages such as high isolation and low cross-polarization can be obtained.The measured results show that the antenna operates in the frequency band of4.5-5.31 GHz and the impedance bandwidth is 16.2%,covering the 5G communication band from 4.8 to 5 GHz.A maximum gain of 9.2 d Bi is achieved in the band.In addition,due to the complete symmetry of the antenna structure and the differential feeding method,the proposed filter antenna has a stable radiation pattern in the working frequency band and achieves a low cross-polarization level.At the same time,ultra-high polarization isolation of more than 70 d B was obtained.(2)A differential filtering array antenna is proposed.In order to achieve a stronger signal receiving capability,the differential filter antenna was transformed into a 1x4 array antenna,and an array antenna was designed.The resulting differential filtering antenna array operates at a center frequency of 4.9GHz and has a peak antenna gain of 15.7d Bi,which has stronger radiation performance,and exhibits good filtering effect and high common-mode rejection.(3)A reconfigurable antenna with differential feed pattern is proposed.Parasitic patches with PIN diodes are loaded on both sides of the dipole antenna as the guide of the antenna,and the work of the guide is controlled by switching the diode switch,so as to realize the reconfigurable pattern of the pattern.The simulation results show that the antenna operates in the 3.35-3.83 GHz band,with a relative bandwidth of 13.4% and an average gain of 6.5dBi. |
