Design of Wide-Band Pseudo-Elliptic Waveguide Filters With Cavity-Backed Inverters

This letter presents a method for the design of wide-band pseudo-elliptic waveguide filters without resorting to global full-wave optimization. In this approach, we introduce and employ two novel cavity-backed inverters, which produce transmission zeros in the out-of-band response, however, whose frequency response in the passband is similar to that of normal iris inverters. As a design example, a pseudo-elliptic waveguide filter with transmission zeros in the lower and upper frequency bands are designed and fabricated. The results show good equal-ripple performance in the passband and improved rejection performance with preset transmission zeros beyond the passband.