Time Domain Technique in Three Antenna Near-Field Measurement Methods

摘要

It is a common knowledge that time domain technique is of the advantage over frequency domain technique in eliminating undesired multiple reflections in antenna measurement techniques. This paper investigates the fundamentals of time domain technique in near-field measurement and introduces the implement of Antcom ITDNFS (Impulse Time Domain Near-Field System) and its time domain settings, especially the determination of time gates. To improve the time domain raw data, the properties of observed system impulse response and three common types of unwanted signals in near-field measurement are analyzed. It reveals that the advantage of time domain technique in some planar and cylindrical scanning cases is not as significant as it in spherical cases because the dominant errors caused by mutual couplings are unable to distinguish and remove. This paper further studies the applicability of time domain technique in three near-field scanning types by testing examples. Comparing resulting far-field patterns between ITDNFS and conventional frequency domain near-field system indicates good agreement or better performance attained by time domain technique.