Site Validation Based on the Use of Broadband Calculable Antennas and Numerical Simulations

Semi-anechoic chambers and open area test sites validation in the frequency range between 30 MHz and 1000 MHz is typically carried out by comparing measurement results obtained by using a pair of biconical and log-periodic (broadband) dipole antennas with tabulated reference values of normalized site attenuation (NSA) provided by CISPR and ANSI standards. It is here shown, through simulations based on validated electromagnetic models of biconical and log-periodic dipole antennas, that the NSA reference values reported in the CISPR 16-1-4 and ANSI C63.4 standards may differ up to about 3 dB from those obtained by using pairs of calculable broadband antennas. Large deviations are observed both in the lower frequency range (30 MHz-250 MHz), where the use of the biconical antenna pair is prescribed, and in the higher frequency (300 MHz -- 1 GHz), where a pair of log-periodic dipole antennas is required. The observed 3 dB deviation is not negligible since the tolerance set by the standard is ± 4 dB.