Dimensional synthesis method for wide-band waveguide iris filters

This study presents a dimensional synthesis method for the design of wide-band waveguide iris filters without global optimisation. In the synthesis method, an alternative edge frequency mapping method is introduced and applied. In addition, an improved iris model with the exponent-weighted turns ratio is proposed in order to incorporate the frequency dependence of inverters. Based on the edge frequency mapping method and the improved iris model, a dimensional synthesis procedure is then presented. As design examples, two H-plane waveguide iris filters are designed for 17.6 and 20.2% fractional bandwidth, respectively. The measured and calculated results show good equal ripple performance within the whole frequency band.