Low cost, one-shot switch waveguide window

Abstract

Inexpensive and reliable apparatus for blanking the signal path between an antenna and a transmitter or a receiver to protect them from harmful radiation in the absence of power forms supplied thereto. The apparatus is preferably formed as a printed circuit waveguide switch window having a plurality of parallel conductors, such as metal wires or printed circuit traces, disposed on a dielectric substrate. The waveguide switch window is secured between two sections of waveguide. The conductors have a predetermined separation and width that are designed to appear as a solid metal surface that rejects radiation over a wide bandwidth. A bias terminal is coupled to the plurality of conductors, and insulating material is disposed between the bias terminal and the conductors to insulate the top portion of the grid array from the adjacent waveguide. The lower portion of the grid array is grounded to the adjacent waveguide. When the waveguide switch window is in its protective, blanked state, it blocks undesired radiation from entering the antenna and destroying sensitive components in the receiver. When a predetermined voltage is supplied to the bias terminal, it vaporizes the grid array and opens the waveguide switch window to allow normal operation of the antenna and receiver. As proven by tests, the waveguide switch window provides radiation immunity against high level input radiation power and high isolation (30 dB) for receiver protection in the blanked state, and with no measurable loss in the unblanked state.