A DOUBLE OPTIMIZED TRANSMISSION ZEROS BASED ON PI-CRLH DUAL-BAND BANDPASS FILTER

In this paper, design and measurements of a highly selective π-CRLH dual-band bandpass filter, with transmission zeros optimized to serve Wi-Max applications, is presented. The dual-bands are designed at 5.2 and 5.7 GHz with a sharp rejection level between them and transmission zeros before and after the passbands. The filter is designed using coupled gap zeroth order composite right/lefthanded (CRLH) resonators, which results in significant filter size reduction. Furthermore, two different coupled π-CRLH filters are discussed through the work development of this paper. The filter design concepts are verified and confirmed using electromagnetic simulations and experimental measurements. Presented results reveal that the proposed filter exhibits a rejection level greater than −20 dB, while maintaining 2 dB insertion loss and better than −25 dB for the transmission zeros with compact size (12 × 16 mm2) which is 70% smaller than similar conventional filters.