Design of a wideband parallel-coupled filtering antenna based on dual-frequency matching condition

Abstract

In this paper, a wideband filtering antenna is designed based on the dual-frequency matching condition. Instead of matching at only one radiating frequency in the conventional filtering antenna design, an antenna element with two radiating frequencies are considered and equivalently modeled as two series-connected parallel RLC resonators, a series inductor, as well as a shunt capacitance. To obtain a wideband impedance matching, last two stages of the parallel coupled-line sections in a filter are synthesized for matching the antenna at two frequencies. Finally, a prototype of a four-pole filtering antenna is designed and fabricated. The measured results achieve a wide bandwidth of 27.8% over 2.12–2.81 GHz with a flat antenna gain of 3.41 dBi over all the filtering band.