Dimensional synthesis for wide-band pseudo-elliptic waveguide filters using cavity-backed inverters

This study presents a dimensional synthesis method for the design of wide-band pseudo-elliptic waveguide filters without resorting to global full-wave optimisation. In this approach, the authors introduce and employ two novel cavity-backed inverters, which produce transmission zeros (TZs) in the out-of-band response, however, the frequency response in the passband is similar to that of normal iris inverters. So, the design procedures for the passband and out-of-band filter responses are carried out independently. As design examples, pseudo-elliptic waveguide filters with TZs in the lower and upper frequency bands are designed, respectively. The results show good equal-ripple performance in the passband and improved rejection performance with preset TZs beyond the passband.