Equivalent circuits of planar filtering antennas fed by apertures

The paper is focused on a design of a three-element filtering patch antenna array using an equivalent-circuit approach. The array is requested to exhibit a prescribed frequency response of a realized gain which corresponds to the output signal of a band-pass filter. When implementing the antenna, no filter elements are allowed to be used. Such an antenna can become a good candidate for the design of filtering antennas (filtennas). We present an equivalent circuit of such an antenna array. The equivalent circuit is validated by a full-wave model of the antenna. The equivalent circuit is transformed to a low-pass prototype filter. The low-pass prototype filter is intended to be exploited for the synthesis of filtering antenna arrays.