Design of a Decoupling Network Utilizing Antennas as Resonators

This paper proposes a design method for a decoupling network between antennas using a patch antenna array as a resonator, aimed at reducing network components. A key challenge in utilizing a patch antenna array as a resonator is the narrow spacing between transmission admittance inversion poles between antennas, leading to narrowband isolation. To address this issue, the study focused on the phase of even and odd modes of the patch antenna and successfully widened the spacing between the inversion poles of the transmission admittance by connecting a transmission line of appropriate length to the antenna. As a result, isolation with two transmission zeros was achieved without the need for an external resonator.