Effect of Quiet Zone Ripples on Antenna Pattern Measurement
Compact antenna test range (CATR) is one of the most commonly used antenna measurement techniques, particularly in the microwave/millimetre wave range. A conventional industry standard for the quiet zone of a CATR is ±0.5 dB amplitude variation and ±5º phase variation to conduct measurement with acceptable accuracy. Such a high standard, however, has not been rigorously verified in theory. And it is in contrast to 22.5º phase variation condition for the far-field method. Being inspired by many measurements, where the quiet zone is not up to the industry standard while satisfactory results are still obtained, this paper systematically investigates the effect of quiet zone performance on the radiation pattern measurement. It aims at searching for a guideline specifications for the construction of a CATR. Theoretical models have been built to predict the quiet zone performance on the antenna pattern measurement, particularly on the main beam. Many factors have been considered, such as amplitude and phase ripple, amplitude/phase taper, and electrical size. In coupling with experimental study, it is shown that a much more relaxed condition can be followed depending on the required measurement accuracy.