Miniaturized dual-mode bandpass filter using inductively loaded ross-slotted patch resonator

An inductively loaded cross-slotted patch resonator is presented to build up a miniaturized dual-mode bandpass filter. By terminating the cross-slot on the square patch with the T-shape slot stubs, the resonant frequency is exhibited to be largely lowered due to an additional inductive loading, implying a capacity in size-miniaturization. In parallel, the rectangular slit is introduced at the four sides of the cross-slotted patch to facilitate the tightened parallel coupling between the feeders and resonator. A dual-mode filter with the patch size of lambda/4 squared is then designed and predicted results are evidently supported by measurement.