Using ANSI C63.5 standard site method antenna factors for verifying ANSI C63.4 site attenuation requirements

Alternative open area test sites such as semianechoic chambers or sites covered by all-weather enclosures must meet the site attenuation requirements set forth in ANSI C63.4 before being used to make FCC Part 15 radiated emission requirements. The site attenuation test requires two antennas with known antenna factors. These factors can be obtained by measuring the site attenuation of a reference site using the standard site method (SSM) referenced in ANSI C63.5. However, imperfections in the reference site can result in errors that become part of the antenna factors. Depending on the sign and magnitude of these errors, it may not be possible to show that the alternative site meets the site attenuation requirements of C63.4 even though it may be a good site. The difficulty with using the standard site method for obtaining antenna factors is the initial assumption that the reference site is ideal without providing any means of verifying it