Antennas and the associated time domain range for the measurement of impulsive fields

The construction and evaluation of a TEM horn antenna designed at NBS to be used as a transfer standard to generate and measure impulsive electromagnetic fields is reported. The different electrical field generation and measurement techniques were analyzed to determine the major sources of error and establish a standard of impulsive field strength having a well establish statement of accuracy. The evaluation of this horn was done in two independent ways, by placing the horn in the field of a conical transmission line, and by a three antenna intercomparison. The two methods were found to agree within + or - 3 dB over the range of 0.6 to 5 GHz. Part of this disagreement is due to the assumption of far field conditions, and an experimental technique is described which determines the frequency range over which this assumption is valid.