INTEGRATED EVANESCENT MODE FILTER WITH ADJUSTABLE ATTENUATOR.

摘要

A waveguide evanescent mode filter (8) is integrated with a monolithic microwave integrated circuit (MMIC) (6) by forming both the MMIC circuitry (10) and the waveguide filter (8) on a single substrate that forms a common ground plane (15) for both elements. The waveguide (14) has a superstructure with an interior recess that is contoured to provide a desired cutoff frequency. The underlying portion of the ground plane can form the lower portion of the waveguide (14) itself, and can also be contoured to define the cutoff frequency. Adjustable attenuation is provided by a resistive card (26) that can be inserted by different amounts into the waveguide (14).