A Method of Generating Radiation Nulls Utilizing Inherent Resonance Modes for Dual-Polarized Filtering Dipole Antenna Design

This communication proposes a method of generating radiation nulls for designing wideband dual-polarized filtering dipole antenna with simple structure. The proposed antenna consists of a pair of crossed dipole radiators, a ground plane, and a balun. Different from the previously proposed methods, the filtering performance of the proposed antenna is achieved by fully exciting the out-of-band resonance modes of the balun and radiator. The proposed dual-polarized filtering antenna has a very simple structure without any extra circuit and nearly has no radiation performance degradation. One radiation null and two other ones are generated at the lower and higher edges of the passband to achieve good frequency selectivity, respectively. The proposed antenna has high efficiency of about 90% inside the operating bandwidth of 1.7-2.8 GHz and out-of-band gain suppression of more than 20 dB.