A Novel Collimation Correction Of Active Array Antenna implemented In Risat

摘要

Traditionally, collimation error estimation of an active array antenna is carried out from the Near-Field (NF) hologram where all the elements of the active array antenna are illuminated simultaneously. However, typical NF processing resolution is ～λ and typical element spacing in scan direction is less than ～0.7 λ. Consequently it becomes very difficult to resolve amplitude and phase errors, especially in the presence of sharp amplitude and phase discontinuities. Further, this method requires area scanning of antenna in near field to obtain . hologram. This paper presents a novel method, where amplitude and gain response of individual rows are measured using a single scan. For this purpose, TR modules are switched one at a time. The correction coefficients, estimated with this method, are very accurate and free from aforementioned distortions because of wide impulse response of NF processor. Further, only a linear scan is sufficient to assess the correction factors with significant impact on the time required for such estimation.