Quarter-Wave-Coupled Corrugated Filter
Simple, Reliable & Powerful / US Patent #6,169,466 by Rousslan Goulouev
E-plane corrugated waveguide filter based on plurality of corrugated resonators coupled by quarter-wave impedance inverting transformers. Due to high loaded Q of the resonators the filter provides pseudo-band-pass frequency response not typical for conventional corrugated filters.

Advantages over conventional corrugated filters
1. More frequency spectrum rejection. Provides steeper roll-off and additional rejection of frequency spectrum between the pass-band and waveguide cut-off. Can replace a cascade of conventional iris and corrugated filters for many applications.
2. Higher peak power handling.
3. Easy to design. Five minute exact design using simple MathCAD procedure.
4. More stable for manufacturing tolerances. Regular milling machinery can be used.

1. 50%-70% Longer than conventional corrugated filter.
2. Slight higher insertion loss.

Frequency response; (1) WR75 waveguide range, (2) In-band insertion loss, (3) harmonic transmission measured using standard calibration, (4) harmonic transmission measured using exciters of spurious modes.