Antenna Calibration Methods for Antenna Factor Measurements

In the fields of electromagnetic interference and electromagnetic compatibility, it is important to measure the strength of the electric field originating from electric devices. For this purpose, knowledge of the antenna factor of a receiving antenna is necessary. According to international standards, the accurate measurement of the antenna factor involves the use of calibration test sites characterized by very large sizes of both the ground plane and the empty space volume above it. As a consequence, these setup conditions make the antenna factor measurements quite expensive for the customer. In this paper, the authors discuss the well know antenna-based and site-based methods as well as recently measurement method called Antenna Impedance Method as able to obtain the free-space antenna factor. Moreover, the authors investigate on the suitability of semi-anechoic chamber for reliable antenna factor calibrations. In particular, the experimental measurements of the antenna factor obtained by using the antenna impedance method were compared with Standard Field Method and the data provided by the manufacturer of three antennas (Biconical, Log-periodic and Horn antenna) founding an agreement with the international standard ANSI C63.5-2006.