Compact bandpass wageguide filters based on modified split-ring resonators

Small-sized waveguide bandpass filters based on modified split-ring resonators are considered. Extremely compact dimensions are their salient features distinguishing them from known designs. The filters demonstrate enhanced out-of-band suppression in a broad frequency range. We propose a way to reduce the longitudinal dimensions of the filter, consisting in rotation of the adjacent resonators. Arrangement of adjacent sections at a right angle to each other provides a required coupling coefficient between the resonators, separated by shorter coupling guide sections.