Peculiarities of Time Domain Antenna Measurement Using Ultra-Short Pulses

Abstract

This paper proposes a method for measuring the antenna radiation pattern (RP) with ultrashort pulses using the tower method at an open test site. It has been shown by experiments that the far-field boundary does not depend on the pulse duration if the bandwidth of exciting pulse exceeds that of antenna. When measuring in the interference zone, it is possible to separate the direct pulse and the pulse reflected from the underlying surface in time domain at any RP shape of the antennas used. The time window method makes it possible to exclude reflections from the ground and simulate the free space. The energy attenuation typical for the free space has been demonstrated when radiating at raised antennas and using a time window. In this case, there is no interference pattern typical for narrowband signals. It is shown that if the pulse reflected from the ground cannot be eliminated, the attenuation acquires the character of propagation along the underlying terrain. To demonstrate the use of the proposed technique, measurements of the horn antenna RP obtained by the pulse method are presented, and the results obtained are compared with the measurements in an anechoic chamber employing narrowband signals.