Narrowband/wideband decoupling networks for antenna arrays and excitation ditribution control

In this paper, we present narrowband/wideband decoupling networks for antenna arrays. The narrowband decoupling network is composed of only lumped elements, and the design equations that are valid for arbitrary two-element antenna arrays are derived. Moreover, we discuss the excitation distribution of the antenna elements when this network is applied. The wideband decoupling network consists of directional couplers, a transmission line, and a parallel resonant circuit. This network is effective for strongly frequency-dependent antenna coupling, and the design method is derived. We design two-element antenna arrays with the narrowband/wideband decoupling networks and confirm the validity of these networks.