Using the calculable dipole antenna for antenna calibration and validation of EMC test sites

The validation of a calibration test site is a precursor to the calibration of antennas. Non-uniformity of electromagnetic fields in the test site impact directly on the attainable uncertainty of antenna gain or antenna factor. The validation of a test site relies on calibrated antennas, whose calibration relies on a high quality test site. This interdependence means that neither can be measured precisely until at least one is known precisely. In the case of a test site with a ground plane, and for frequencies as low as 30 MHz, this conundrum is beautifully solved by the use of the calculable dipole antenna. The antenna factor is precisely calculable from the antenna dimensions, combined with the measured S-parameters of the balun. The international standard CISPR 16-1-5 describes the use of the calculable dipole to validate test sites that are used to calibrate EMC dipole-like antennas. This paper gives the rationale for the validation processes described in CISPR 16-1-5. The usability of this approach is enhanced by broadbanding the performance of the calculable dipole to over 200% bandwidth, which is achieved by method-of-moments code.