A compact square open-loop resonators with meander spurlines feeder

A compact square open-loop resonators with meander spurlines feeder is proposed to develop the square open-loop bandpass filter. The filter is based on square open-loop resonator consists of four identical patches with attached to an inner corner of the square open-loop. The proposed square open-loop resonators with meander spurline structures placed at the input and output ports. The proposed square open-loop resonators have a wide stopband resulting from the meander spurlines. A prototype filter is designed at 1.95 GHz. The return loss is greater than 13.5 dB, and the insertion loss better than 2.65 dB.