Analysis of log periodic dipole array antennas for site validation and radiated emissions testing

Log periodic dipole array (LPDA) antennas are one of the most widely used antenna types for normalized site attenuation (NSA) and radiated emission (RE) testing. A thorough understanding of the possible error sources associated with the calibration and application of LPDAs for EMC tests over a ground plane is essential for evaluating and minimizing measurement uncertainties. Systematic errors are present in the standard site calibration and NSA measurement, which are independent of random effects and equipment uncertainties. In an effort to determine the effects on NSA and RE testing, these errors are examined using a numerical moment-method model and measurements. Error contributions from mutual coupling between antenna and image, active phase center variation, radiation pattern, and cross-polarization effect are investigated.