High-Isolation Dual-Frequency Operation Patch Antenna Using Spiral Defected Microstrip Structure

This letter presents a practical method to improve the performance of a dual-frequency dual-polarized patch antenna via increasing the isolation between receiving and transmitting ports using spiral defected microstrip resonators. They are added to the feeding lines to enhance the ports isolation of the antenna. Experimental results show that the proposed method improves isolation to higher than 55 dB at both frequency bands.