Correction Of Antenna In OATS

The theoretical NSA values given by the standards are grounded on the assumption that transmit and receive antennas are infinitesimal dipole antennas which is inappropriate to measurements. Besides, the electric field only contains the far field part in the theory model no matter in ANSI C63.4-2003 or ANSI C63.5-2006. Therefore, considering that the coupling effect in near field may cause obvious error, correction of antenna factor is requisite for every NSA measurement, especially when tuned dipoles are employed. In this paper, first I analyze the EMC measurement theory and get the formula of correction factors of antenna, then the simulated value of some parameters used in the measurement is compared with the theory value, and the software based on the method of moments is chosen to calculate the correction factor of antenna at 3m and 10m distance above a finite metal plane, finally the simulated results are compared with that given by ANSI C63.4 and CISPR and modify the measurement value. That is, at the end of this paper, taken the influence of actual test site and mutual coupling between antenna and test site into account, the problem of values traceability regarding test site have been solved, and the uncertainty of the measurement has been lessened.