Quasi-elliptic two pole microstrip filter with source-load coupling

Second order filters are very attractive for front-end part of wireless system in a case of low insertion loss and compact size required. Selectivity of a filter can be improved using additional transmission zeros. A planar two pole filter which has two finite transmission zeros can be realized using dual-mode resonator or 0/spl deg/ feed structure. The filter described in this paper has transmission zeros which realized using coupling between input and output microstrip lines. We also presented rejection filter, which used for improving rejection performance of bandpass filter.