Cylindrical/Spherical Near-Field Antenna Measurement System

A low-cost, fully operational cylindrical and spherical near-field antenna measurement system designed, built, and programmed by a University of Rhode Island Capstone team is presented. The goal of this project was to modify an existing planar near-field system and apply new processing techniques to extract the far-field patterns of an antenna under test (AUT) of any physical shape. The aim of this paper is to present the design methodology and implementation of adding the capability of acquiring and processing cylindrical and spherical waveforms to the planar system and the corresponding immediate, positive impact of this fully-functional measurement system on the sponsoring company, Applied Radar, Inc. The development methodologies for adding the cylindrical and spherical measurement capabilities were identical and encompassed two steps. The first step was designing the system to be able to collect and characterize the electric fields in their respective coordinate system. Secondly, the collected electric fields undergo a post-processing routine which has been customized to each waveform coordinate system and results in an accurate representation of the far-field pattern of the AUT. The results of the near-field measurements are shown and the impact of this added capability on Applied Radar, Inc. is discussed.