Compact dual-band filtering antenna based on capacitor loaded patch radiator

A chip capacitor loaded dual-band microstrip patch filtering antenna with closely spaced bands is presented. It is shown that an additional resonance can be created in the frequency response of a microstrip patch antenna by etching a slit on its signal plane and loading it with chip capacitors. The frequency of the new resonance can be controlled through the chip capacitor. For dual-band design, the new resonance frequency (2.46 GHz) is placed close to the patch antenna resonance frequency (2.4 GHz) to obtain a frequency ratio of 1.025. The realized gain in the upper and lower bands is 7.7 dBi and 7.1 dBi leading to estimated efficiencies of 81.5% and 73% respectively. The patch antenna is implemented on a single layer printed circuit board (PCB), occupying an area of 0.54 λ
_g
× 0.48 λ
_g
.