Conical Near-Field Antenna Measurements [AMTA Corner]

A near-field measurement technique for the prediction of asymptotic far-field antenna patterns from data obtained from a modified cylindrical or plane-polar near-field measurement system is presented. This technique utilizes a simple change in facility alignment to enable near-field data to be taken over the surface of a conceptual right cone [1, 2], or right conic frustum [3, 4], thereby allowing existing facilities to characterize wide-angle antenna performance in situations where hitherto they would perhaps have been limited by truncation. This paper aims to introduce the measurement technique, and to describe the novel probe-corrected near-field-to-far-field transform algorithm. The algorithm is based upon a cylindrical-mode expansion of the measured fields. Preliminary results of both computational electromagnetic simulations and actual range measurements are presented. As this paper recounts the progress of ongoing research, it concludes with a discussion of the remaining outstanding issues, and presents an overview of the planned future work.