Equivalent Lumped-circuit Analysis of the Filtering Two-Elements Series-Fed Array Antenna

A filtering two-elements series-fed vertical array antenna is presented in this paper, and the equivalent filtering lumped-circuit of the antenna is analyzed. The antenna consists of the dipoles for radiation and double-sided parallel strip line (DSPSL) for feeding. The dipoles are designed as the series resonators. The DSPSL is shorted in both ends and served as a parallel resonance. Because dipoles are fed in-phase by the DSPSL structure, the series resonators are excited in parallel. By introducing the J-inverter, the series resonators are transformed to the parallel resonators. Then these lumped-circuits are merged into a second-order filtering network by applying the network theory. Eventually, the proposed antenna can be regarded as the second order filter.