WAVEGUIDE FILTERS WITH PLANAR CIRCUIT INSERTS SUITABLE FOR INTEGRATION OF ACTIVE DEVICES

This paper presents a class of waveguide bandpass filters with conformal iris patterns made of planar circuits suitable for integration of active devices. Multiple planar inserts are located along the propagation path with specially designated spacing between two adjacent planar inserts on which the iris patterns are etched. The electrical performance of such novel filters with the enclosure of a circular waveguide is demonstrated by the field-theoretical design and experimental characterization of a three-pole Tschebyscheff-type filter. Results of this type of planar-insert-based waveguide filter is compared with its conventional all-metallic iris counterpart designed at the same center frequency, showing nearly an identical frequency response between the two different topologies. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 77–80, 1997.