Improved Broadband Antenna Gain Measurements Through Multipath Mitigation Using Combined Robot Motion Stirring

Published

July 9, 2026

Author(s)

Joshua Gordon, Benjamin Moser

Abstract

Abstract—In this paper we describe a technique that uses coordinated motion of two robotic antenna positioners to reduce the influence of chamber multipath reflections during antenna gain measurements. This technique demonstrates a new application that leverages the capability of modern robotic antenna ranges to accurately position pairs of antennas relative to an anechoic chamber over a wide range of poses (i.e., position and orientation). In this technique, through calibrated kinematic control of the robotic positioners, antenna-pair poses are dynamically changed relative to the bounds of the chamber (walls, floor, and ceiling), while maintaining the measurement geometry in the reference frame of the antenna pairs. This dynamic movement of the antenna pairs creates a scenario where the chamber is effectively moving relative to the reference frame of the gain measurement geometry, thus resulting in "stirring" of the multipath chamber reflections. Through this stirring process, the effect of multipath reflections can be effectively averaged out, allowing antenna gain to be recovered even in the presence of appreciable multipath chamber reflections. This is especially useful for antennas that produce significant multipath reflections, and that would otherwise be challenging to measure inside a chamber. For example, those antennas with relatively lower gain and or which operate at lower frequencies where radio frequency absorber is less effective. As a demonstration, we apply this stirring technique to the three-antenna gain extrapolation method to improve gain calibrations that involve broad band dual ridge horn antennas. Gain measurement results in the WR430 and WR650 bands that incorporate NIST standard gain horn reference antennas and lower gain dual ridge broadband horn antennas are presented. We show that antenna gain can be accurately recovered with uncertainties of ≈ ± 0.07 dB, even when measurements are significantly perturbed by several dB due to chamber multipath reflections caused by the lower gain dual ridge horn antennas.

Citation

IEEE Transactions on Antennas and Propagation

Pub Type

Journals

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Keywords

Antenna, antenna gain, dual ridge antenna, dual ridge waveguide antenna, gain, gain extrapolation, multipath, reflections, robotic antenna measurements.

Citation

Gordon, J. and Moser, B. (2026), Improved Broadband Antenna Gain Measurements Through Multipath Mitigation Using Combined Robot Motion Stirring, IEEE Transactions on Antennas and Propagation, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961127 (Accessed August 9, 2026)

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