Short-circuited series stubs for application in uniplanar low-pass filters

摘要

An alternative uniplanar low-pass filter with series stubs is presented in this paper and its upper stopband is extended up to five times of its cutoff frequency. The basic filter structure primarily consists of short-circuited series stubs on slot line and connecting lines on coplanar waveguide. Under the target of Chebyshev function low-pass frequency responses, all the element values involved in this filter topology is determined via efficient synthesis design approach rather try-to-cut optimization approach. Later on, the connecting line between adjacent stubs is replaced by its equivalent T-shaped transmission line to suppress the higher order harmonic bands. As design examples, two five-pole uniplanar filters with and without harmonic-suppressed elements embedded are designed, fabricated and measured.