Formulation of normalized site attenuation in terms of antenna impedances [EMI measurement applications]

General formulas for normalized site attenuation (NSA) are derived in terms of antenna impedances by using the two-port circuit theory to show the effects of mutual coupling. The investigations focus on the antenna factors and antenna calibration procedures that are appropriate for NSA, and the validity of the NSA concept is discussed on the basis of these theoretical investigations. The NSA measurements are found to be appropriate for site validation when using broadband antennas having constant antenna factors. It is theoretically concluded, however, that the original concept of the NSA may not be applicable to the use of tuned dipole antennas, even after adopting the correction factors specified in the existing ANSI standard. NSA is shown to require different correction factors if the antennas have changeable antenna factors