A compact high selective coupled gap CRLH TL based bandpass filter

This paper exhibits a new compact high selective gap band pass filter designed for the 5 GHz WiMAX service. The filter is based on fourth order coupling of coupled gap composite right left handed transmission line resonators. The resonators are designed to demonstrate a zeroth order mode at the passband center frequency for filter size reduction. The filter has a compact size 20×20 mm². The design concepts of the coupled filter response are discussed and verified using full electromagnetic full wave simulations and confirmed by experimental measurements with good agreements. The results confirm that the filter has 1.5 dB insertion loss and better than -25 transmission zero.