Microwave breakdown on the RANT flight antennas: Preflight tests

The report summarizes all of the laboratory breakdown data obtained by the contractor with the RANT S-band and VHF flight antennas. Comparisons are made between the observed and expected values of breakdown power for the observed values of pulse duration to breakdown for all of the data. The calculations were done using the Aerospace breakdown code (BRKDN4) for pulsed breakdown in uniform air in a nonuniform electric field. It was concluded that values of power incident on the antennas are in better agreement with values deduced from preassembly individual component tests than with those from the incident-power measurement system incorporated in the assembled vehicle. It was further concluded that best agreement between predicted and observed breakdown power is obtained if it is assumed that the antenna efficiencies are 0.49 for VHF and 0.68 for S-band.