A Low Profile, Wideband Filtenna Based on Differential Feed Structure

A low profile, wideband filtenna based on differential feed structure is proposed in this paper. The filtenna with good out-of-band rejection characteristics, composed of a modified radiation patch, a hybrid loop bandpass filter and a differential feed structure used to generate two differential signals with equal amplitude and 180° phase difference. Besides, the modified patch is also used as the laststage resonator of the filter to broad the bandwidth of the antenna. In the simulation, the center resonance frequency of the antenna is 2.31 GHz, the 10-dB fractional impedance bandwidth is 8.66%, and peak gain is 5.0 dBi. Excellent performance characteristics are demonstrated including flat passband realized gain values and filter responses with sharp roll-off rates and high out-of-band suppression levels. The numerical analysis is performed using HFSS 18.0.