A Compact Dual‐Band Filtering Antenna With Slot‐Modified Ground Plane for 2.4/4 GHz Short‐Range Wireless Applications

ABSTRACT In this letter, a compact dual‐band filtering antenna with a slot‐modified ground plane is proposed for 2.4 and 4 GHz dual‐band short‐range wireless applications. The filtering antenna is implemented on a single piece of FR4 substrate. It consists of a feeding line, two long rectangular slots, a semicircular annular patch, and a peripheral via array. The two long rectangular slots are mainly utilized to generate three resonances so as to form the passband. The annular patch is employed to introduce an additional resonance to broaden the impedance bandwidth. The peripheral via array is added to reshape the bottom layer current distribution to suppress unwanted modes and enhance the filtering response. To verify the design concept, the prototype is fabricated and measured. The measured results are in good agreement with the simulated ones demonstrating that the antenna achieves two operating bands centered at 2.52 and 4.16 GHz, with an impedance bandwidth of 41.5% and 7.3%, respectively. The measured peak realized gains are 7.0 dBi and 4.5 dBi in the lower and upper passbands, respectively, while the radiation patterns maintain good radiation characteristics.