The Research Of Ultra-wideband Antenna And Its Array Technology

With the continuous advancement of technology,broadband high-resolution radar,high-throughput mobile and satellite communications,global navigation satellite systems,wireless power transmission,electronic warfare and other military civilian systems have developed rapidly.Antennas are an important part of these systems.As the emission structure of electromagnetic signals,the quality of their indicators directly affects the overall performance of the communication system.As the functions of communication systems become more and more complex,higher requirements are imposed on the applicable bandwidth of antennas.Therefore,research on ultra-wideband antennas and their arrays has received more and more attention.Ultra-wideband antenna arrays have advantages such as strong beam directivity and higher gain compared to ultra-wideband antenna elements.This paper studies the ultra-wideband Tightly Coupled Array(TCA)technology.In this paper,the TCA technology is deeply analyzed,and its equivalent circuit model is introduced.The coupling effect of two adjacent elements in the antenna array and the selection of the grounding plate position are added to expand the bandwidth of the antenna array.The paper also analyzes the balance and impedance transformation characteristics of its feed.According to the theoretical analysis,a TCA antenna unit powered by Wilkinson and Balun is designed,and the upper layer of the radiation structure is loaded with the matching layer.The simulation results of the antenna element under the periodic boundary conditions show that the VSWR in the band of 3.1-16 GHz is less than 2,and the usage requirement is still satisfied within the scanning range of ±45° on the E surface.Then the dielectric matching layer was replaced and a double-layer frequency selective surface(FSS)was designed.The high-frequency characteristics of this structure are improved,but the performance of the dual-polarized unit is lower than that of the wide angle impedance matching(WAIM).The dual-polarized TCA composed of the WAIM layer antenna elements is simulated,and the VSWR is substantially less than3 in the 3.6-18 GHz band.Then,the lead-in structure is added to the WAIM.Through the simulation analysis of several guiding structures,a guiding structure similar to the Yagi antenna is designed,which enhances the beam directivity of the antenna array and improves the gain.The TCA unit with the guiding structure is expanded into a 4×4 dual-polarized tightly coupled array,which is processed,assembled and tested.The test results show that S11<-6d B(stationary wave ratio is less than 3)in the 2-12 GHz band;the highest point of the gain is slightly deviated from the main direction at the 6GHz frequency point,and the axial symmetry of the other frequency points is better.The cross-polarization suppression of each frequency point is greater than 10 d B.