A Study Of Dual-polarized Microstrip Antennas

Based on the UHF band dual-polarized microstrip antenna technical indicators, designing a square microstrip patch antenna which is working in a center frequency of 642 MHz in the UHF band with a direct feed and using Ansys HFSS software for the modeling and simulation. Because the gain of a single antenna is about 8.5d B, designing the corresponding feed network, establishing the square microstrip patch antenna array with a direct feed. After the simulation, Antenna performance parameters are obtained for example(VSWR), port isolation, radiation pattern and cross-polarization parameters equality. In the work of the band(606-678MHz), the VSWR of the antenna is less than 1.5, port isolation is more than 17 d B and gain is greater than 11 d B. Cross-polarization level is less than-21 d B. Front to back ratio is more than about 19 d B.Port isolation is not high, it is more difficult problem during the research process.Finally, the antenna is processed into a physical model, and tested. Initially the test results are not ideal, to find the reasons, the program of original fixed radiation patch has been improved to increase the number of screws, changing pads under medium size measures can effectively improve the flatness of the radiation patch, as well as effective controlling the radiation patch and the parasitic patches’ height. The antenna after commissioning were tested, the test results are consistent with the simulation results to verify the correctness of the design.The study results show that the design of the square microstrip patch with the coupling feed array antenna is feasible. The simulation and test results show that the performance indicators meet the design requirements, which increases the valuable experience for the future design of such antennas.