Design of high selectivity filtering antenna based on multi-coupling path

Abstract

In this paper, a filtering antenna with high selectivity is proposed. The filtering antenna consists of λ/4 resonator and a rectangular patch. The λ/4 resonator is fed by microstrip feed line with short-circuited via. The rectangular patch is used as the radiator of filtering antenna and is fed by the λ/4 resonator through an H shaped aperture in the ground. By introducing a new coupling path between feed line and rectangular patch, two radiation nulls appear at the both sides of the bandpass of gain, which effectively improve the selectivity of the filtering antenna. The design results show that the filtering antenna operates at 3.37 GHz with fractional impedance bandwidth of 10.3%, and two radiation nulls appear at 2.9 GHz and 3.86 GHz.