Power limiting apparatus

摘要

Power limiting apparatus for use in a sensitive receiving system includes a gas-filled coaxial hermetically sealed line. The inner conductor includes a central region of reduced diameter connected to a metallisation layer between the inner and outer conductors. An annular gap electrically isolates the outer regions of the metallisation. When excess energy enters the device, gas breakdown occurs across the gap to produce a plasma which reflects the excess energy and prevents it travelling onward to sensitive receiver stages. The gap and adjacent metallisation act as a capacitor which is incorporated into a wideband filter for example a Chebychev filter, the reduced diameter region acting as an inductor. This tunes out the effects of the capacitance during normal operation of the device when low power signals are transmitted through the device to the receiver circuitry.