A Cascaded Resonator Decoupling Network for Two Filtering Antennas

In this paper, a novel method for the decoupling between two filtering antennas is presented. The mutual coupling between two filtering antennas is investigated and a coupled-resonator decoupling network (DN) is developed. This coupled-resonator DN is co-designed with the coupled filtering antennas with little effect on the original filtering responses. By connecting this network to the coupled antennas in parallel, the mutual coupling between two 2 nd order filtering antennas can be suppressed dramatically. A step-by-step realization of the DN is provided. To verify the concept, a prototype using the proposed DN was fabricated and measured. Full-wave simulations and measurements indicate that this coupled-resonator DN can enhance the isolation between two filtering antennas up to 30 dB without significantly affecting the filtering performance of each antenna, at a cost of 1.15 dB efficiency drop.