Various estimations of composite Q-factor with antennas in a reverberation chamber

Abstract

This paper deals with the estimation of the composite Q-factor in a reverberation chamber using one or two antennas (possibly a set of them). Most of Q-factor estimations provided in literature are based on the estimation of the ensemble average of the electric power captured at the terminal of a receiving antenna, the EM field being produced with another one. We first highlight that using two antennas and a vector network analyzer, three different estimations are possible and they are found experimentally to be almost equivalent. Second, removing one antenna the Q-factor may change mainly in the frequency range for which the Q-coefficient of an antenna is no more negligible. Furthermore a post-processing of these two types of measurements allows to extract an estimation of this Q-coefficient alone. This estimation is quite favorably compared to its theoretical estimation based on ideal random field hypothesis.