A novel five-pole microstrip cascade quadruplet filter

Abstract

A five-pole cascade quadruplet microstrip filter is presented. The source and load of the filter couple to two resonators respectively, which establishes two independent quadruplet blocks to control two independent pair of finite transmission zeros. The proposed tuning fingers are introduced to effectively control the strength of cross couplings. Compared to the eight-pole CQ filter, the proposed five-pole CQ filter provides an alternative choice of the filter with two pairs of transmission zeros but has less passband insertion loss. Both simulated and experimental results are given.