Phased array calibration and diagnostics utilizing a student-built planar near-field system

A low-cost planar near-field system was designed, built, and programmed by students from the University of Rhode Island as a Capstone design project sponsored by Applied Radar, Inc. The objective of this paper is to explore the implementation of microwave holographic metrology (MHM) for the use of calibration and diagnosis of phased array performance on this near-field system. The simplest form of MHM is to analyze the near-field data on the collected planar surface, but this is not ideal because of a loss of resolution from the spreading introduced by the measurement distance. A more attractive approach is to project a focused planar “hologram” of the radiation pattern on the surface of the aperture of the antenna under test (AUT) through manipulation of the angular spectrum. The resulting hologram allows for the observation of amplitude and phase distributions on the aperture. This paper will provide insight into the design of the back-projection algorithm and present results for faulted and calibrated phased array scenarios to verify proper functionality of the algorithm.