Millimeter-Wave Near-Field Measurements Using Coordinated Robotics

Published

October 29, 2015

Author(s)

Joshua A. Gordon, David R. Novotny, Michael H. Francis, Ronald C. Wittmann, Alexandra Curtin, Miranda L. Butler, Jeffrey R. Guerrieri

Abstract

The National Institute of Standards and Tech- nology (NIST) recently developed a new robotic scan- ning system for performing near-field measurements at millimeter-wave frequencies above 100 GHz, the CROMMA (Configurable Robotic Millimeter-Wave Antenna) Facility. This cost-effective system is designed for high-frequency ap- plications, is capable of scanning in multiple configurations, and is able to track measurement geometry at every point in a scan. The CROMMA combines real-time six- degree- of-freedom optical spatial metrology, and robotic motion, to achieve antenna positioning to within 25μm rms. A unified coordinated metrology approach is used to track all posi- tional aspects of scanning during near-field measurements. A vector network analyzer is used to capture millimeter- wave amplitude and phase. We present spherical near-field measurements of the forward hemisphere of a 24 dB stan- dard gain horn at 183 GHz made with the CROMMA. Using the configurable scanning ability, two different radii were used to acquire near-field and far-field measurements. The near-field data were taken at a 100 mm radius,(≈ 1/3 of the far-field distance derived from 2D2 /λ). Far-field measurements were taken at 1000 mm radius (≈ 6D2/λ). The E − plane and H − plane patterns are determined from the measurements. The far-field pattern derived from the transformed 100 mm radius near-field measurements are di- rectly compared to the 1000 mm radius measurements. The 1000 mm measurements are then also transformed to the far field at infinity and compared to the transformed 100 mm radius near-field measurements. The two transformed data sets (100 mm and 1000 mm radii) are then compared to the theoretical pattern of the standard gain horn. We de- scribe the system components of the CROMMA and the coordinated metrology approach used. An analysis of the positional repeatability and accuracy that is achievable with this system is also presented.

Citation

IEEE Transactions on Antennas and Propagation

Volume

63

Issue

12

Pub Type

Journals

Download Paper

DOI Link

Keywords

near-field, robotics, far-field, coordinated metrology

Citation

Gordon, J. , Novotny, D. , Francis, M. , Wittmann, R. , Curtin, A. , Butler, M. and Guerrieri, J. (2015), Millimeter-Wave Near-Field Measurements Using Coordinated Robotics, IEEE Transactions on Antennas and Propagation, [online], https://doi.org/10.1109/TAP.2015.2496110 (Accessed October 8, 2024)