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1 year ago in Electrical Engineering By Nithin Rao
What are the common methods for measuring the axial ratio of antennas?
Circularly polarized antennas are often evaluated using axial ratio, which quantifies polarization purity. I want to understand the measurement approaches—both in simulation and physical experiments—the instrumentation required, and how the results are interpreted to assess antenna performance across the operating band.
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By Rubbaiyya Answered 8 months ago
From my experience characterizing circularly polarized antennas, I have seen several reliable methods for measuring axial ratio. One common approach uses a rotating linearly polarized probe in an anechoic chamber to measure received power at different orientations, from which the axial ratio is calculated. Another practical method uses a vector network analyzer (VNA) with orthogonal probes to capture magnitude and phase of orthogonal components. I would recommend ensuring the antenna is in its far-field region and that frequency sweeps cover the operational band. While simulations can predict axial ratio trends, experimental validation is essential because fabrication tolerances, feed network imperfections, and environmental reflections can noticeably affect the measured polarization purity.
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