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2 years ago in Antenna Engineering , Engineering By Divya

How is the axial ratio of an antenna measured, and what is the correct procedure?

I am testing a circularly polarized antenna and need to quantify how pure the polarization is.
Axial ratio is widely referenced, but the measurement setup, probe orientation, and post-processing are not always clear.
I want a systematic, practical procedure that aligns with standards and ensures reproducible results.

All Answers (1 Answers In All)

By Finsi Answered 1 year ago

From my experience, axial ratio measurement is most reliable in the far-field region using a circularly polarized reference antenna or a rotating linearly polarized probe. I have seen practitioners rotate the receiving probe 360°, recording field strengths at multiple angles, then compute the ratio of major to minor axes of the polarization ellipse. I would recommend ensuring accurate alignment, calibration, and sufficient distance from the antenna to avoid near-field distortions. In practice, modern network analyzers or anechoic chamber setups often automate this process, giving reproducible axial ratio plots across the operational bandwidth.

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