Compact Broadband Dual-Band Filtenna With High Selectivity for Vehicle Application

This article presents a compact dual-band filtenna with high selectivity and seven controllable radiation nulls for vehicle application. The proposed filtenna is composed of three dual-mode resonators and a feedline, which are etched on a 3D hollow substrate. To achieve dual-band responses with compact size, three dual-mode resonators are investigated, which feature broad band and controllable frequency ratio to fully cover WIFI bands. For miniaturization, filtering responses are realized by designing multi-path couplings between resonators and the feedline. Without increasing antenna size and extra filtering circuits, seven controllable radiation nulls are realized beside pass-bands. Therefore, the proposed filtenna possesses dual-band and broadband Quasi-elliptical filtering responses with compact size and high selectivity. Moreover, the in-band radiation performance is almost unchanged. To analyze and guide the antenna design, the working mechanisms are presented. For demonstration, the proposed dual-band filtering antenna is implemented with Laser Direct Structuring (LDS). The overall size of the proposed dual-band filtenna is 0.16*0.09*0.04
${\bm{\lambda }}_0^3$
operating with the fractional bandwidth of 10.2% and 13.6%, respectively. The in-band radiation efficiency is of −1.5 dB and −1 dB, respectively. The proposed filtering antenna features compact size, controllable frequency ratio and radiation nulls and high in-band radiation, rendering it suitable for Shark-Fin scenarios.