A hermetically sealed encapsulation for microwave junction diodes

The advent of non-linear capacitor diodes for use in microwave parametric amplifiers has created the need for a low loss, low parasitic encapsulation that can be evacuated, backfilled and sealed with an inert atmosphere. A high alumina ceramic-metal encapsulation has been developed which has these as well as other desirable features: (1) it has a threaded base which can be screwed into either stripline or waveguide circuitry; (2) it has a very low thermal impedance; and (3) although small in size, it is easily inserted into its circuits because it has a hexagonal can which permits the use of a standard six-point socket-screw driver. This encapsulation is currently being used in the fabrication of diffused silicon mesa type diodes intended for use in parametric amplifiers. It has also proved to be a good encapsulation for radar input limiter diodes.