Design of a Novel Filtering Antenna using Open Loop Resonators along with Metallic Via

This paper demonstrates a novel, planar, and compact third-order filtering antenna for WLAN application. The filtering antenna is designed using a conventional rectangular microstrip patch antenna along with a 2nd-order highly selective bandpass filter. This filter is realized with the help of four simple open-loop resonators and a metallic via that connects the source and load. To improve the matching between the filter and antenna, a pair of parallel open stubs are connected to one side of the filter. The simulation results of the proposed filtering antenna exhibit good filtering performance, including a flat gain response with good band-edge selectivity in the desired frequency band (5.33 GHz - 5.52 GHz) with a fractional impedance bandwidth of 3.5% and keeping the center frequency at 5.4 GHz. The other significant results observed are radiation efficiency of 85.3%, cross-polarization rejection level of more than 30 dB, front-to-back ratio (FTBR) of 25 dB, and a realized gain of 5.7 dBi.