Field theory design of a nove circular waveguide dual mode filter

A novel and simple configuration is proposed for the realization of dual-mode filters. The geometry consists of a circular cavity coupled with rotated rectangular waveguides through thick irises, with no need of tuning or coupling screws. The geometry is such that it can easily be analized and optimized using mode-matching technique without requiring any special numerical treatment. Filter performances are shown to be equivalent to those obtained with more complicated geometries.