ZNO VARISTORS FOR PROTECTION AGAINST NUCLEAR ELECTROMAGNETIC PULSES

A prototype NEMP protective device which uses commercial ZnO-based metal-oxide-varistor materials is described and evaluated. The devices are mounted in a standard diode package which threads into the centerline of a specially adapted GR-874T fitting. The varistor response is examined for 500-ps rise time pulses and no delay is evident on this time scale. A low insertion loss of approximately 0. 1 dB at 100 MHz is achieved by reducing the size of the varistor chip. It is concluded that metal-oxide-varistor ceramic materials are very promising for NEMP transient suppressors. It is also likely that the already favorable performance and frequency range of the present devices can be further improved by optimization of the varistor composition, processing schedules, and geometry for this particular application.