A Measurement Technique for Determining the Time-Domain Voltage Response of UHF Antennas to EMP Excitation

A laboratory time-domain measurement technique is being developed that will provide research, development, testing, and evaluation laboratories with the capability to determine quickly and economically the transient response of vhf and uhf antennas. The procedure uses a transverse electromagnetic (TEM) horn radiator to illuminate the test antenna with a short pulse of electromagnetic energy. The transient voltage generated at the output of the antenna by this incident field is approximately the impulse response of the antenna and can be used to obtain the approximate response of the antenna to an arbitrary incident field. In some cases, especially where the response to a nuclear EMP is desired, it may be necessary to process the data in order to compensate for the nonideal waveform that illuminates the test antenna. Analysis of the test equipment indicates that the sampling oscilloscope and x-y recorder used in the experiment provide an accurate means of obtaining data. The wide-bandwidth radiation properties and small physical size of the TEM horn antenna are well suited to laboratory measurements, and a wire model antenna could be designed for field tests. (Author)