Revisiting the Measurement of Gain in Tapered Ranges

Author: Vince Rodriguez
Publication: AMTA 2024
Copyright Owner: NSI-MI Technologies

Tapered anechoic ranges were introduced in the late 1960s. Since their introduction tapered anechoic chambers have become popular tools for the measurement of antenna patterns at frequencies under 1 GHz. Dating back to their first installations, several papers mention the fact that these chambers did not have a spherical wave propagation and thus, the Friis transmission equation to measure gain cannot be applied [1,2]. The array factor theory of taper chambers presented in [3] states that from the point of view of the antenna in the QZ the tapered chamber appears to be a free space environment. The phase behavior across the QZ, reported in [4] appears to agree with the theory since the phase distribution follows the far field equation. In this paper simulations for a dipole and a biconical antenna are performed that suggest that the array factor theory for the tapered ranges while not perfect provides an approximated explanation for their operation. The simulations confirm the measurements done in [2] and additionally show that at some discrete frequencies the propagation in the tapered range does follow closely the free space attenuation.

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