Enhancing isolation between two closely spaced patch antennas using parasitic elements

Two parasitic elements are proposed for enhancing isolation between two closely spaced 5.8-GHz patch antennas. The parasitic elements composed of two simple microstrip lines artificially introduce an extra coupling to cancel out the direct coupling between the two patch antennas, and thus a significant improvement in isolation can be attained. The simulation and measurement validate the decoupling ability of the two parasitic elements. The experimental results indicate that the achieved isolation between the two antennas is better than 20 dB and characterized by a dip of 29.8 dB, with an extremely close edge-to-edge separation of just 1.2 mm.