Variations in mutual coupling correction factors for resonant dipoles used in site attenuation measurements

Site attenuation measurements using resonant dipole antennas are commonly used to certify test sites for compliance testing to the Federal Communication Commission Part 15 requirements. Mutual coupling has previously been shown to affect the impedance of resonant dipole antennas. It is pointed out that a correction factor must be added to ANS C63.4 normalized site attenuation for these measurements to agree with theoretically calculated results below 200 MHz. An accurate method-of-moments technique of predicting horizontal and vertical site attenuation at three meters with resonant antennas is presented. The electrical properties of the antenna balun can be input directly into the model, the exact antenna wire structure including the segmented elements can be included, and all mutual coupling effects are modeled in the problem solution