An Algorithm to Calculate Phase-Center Offset of Aperture Antennas when Measuring 2-Dimensional Radiation Patterns

Report No. ARL-TR-7169
Authors: Patrick Debroux, Berenice Verdin, and Samuel Pichardo
Date/Pages: January 2015; 20 pages
Abstract: Centering the phase center of an antenna onto the rotational axis used to measure its radiation pattern is an iterative and time- consuming process. To facilitate this, a MATLAB algorithm has been developed to calculate the phase-center offset from the axis of rotation of a 2-dimensional antenna pattern. The hybrid algorithm comprises a combination of the 2-point method to calculate the offset along the antennas main beam and an antisymmetry method is used to calculate offset perpendicular to the main-beam direction. The MATLAB algorithm is tested on the E-plane radiation pattern of a cylindrical horn antenna calculated using the high-frequency structural simulators electromagnetic simulation engine, radiating at 5 GHz. The algorithm calculates the phase-center offset to within 15%. Because the algorithm analyzes the unwrapped phase of the radiation pattern, which it converts to offset distance, no ambiguity due to offsets greater than a wavelength exists. Using this algorithm, the phase center of the antenna can be placed coincident to the axis of rotation after the first antenna pattern is measured and analyzed.
Distribution: Approved for public release
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Last Update / Reviewed: January 1, 2015