Artificial complementary resonators for mutual coupling reduction in microstrip antennas

In this paper, mutual coupling between microstrip antennas that radiate in the same frequency band is investigated. A novel technique based on complementary resonators is used to reduce the mutual coupling between such low-profile radiating elements. The technique comprises etching patterned inclusions from the ground plane. The filtering characteristics of the band-gap structure are investigated by means of dispersion diagram analysis and the retrieved constitutive parameters. A 10 dB reduction in the mutual coupling between two patch antennas was achieved using the new structure. Experimental results are presented to validate the concept. The proposed technique can be useful to minimize coupling and co-channel interference in multi-band antennas.