Antenna Measurement Implementations and Dynamic Positional Validation Using a Six Axis Robot 1 David R. Novotny † , Joshua A. Gordon, Michael Francis, Ronald Wittmann, Alexandra Curtin, Jeffrey Guerrieri Communications Technology Laboratory National Institute of Standards and Technology Boulder, CO, United States of America † david.novotny@nist.gov Abstract—We have performed spherical and extrapolation scans of two antennas at 118 GHz using a commercial 6-axis robot. Unlike spherical scanning, linear extrapolations do not precisely conform to the natural circular movement about individual robot axes. To characterize the quality of the data, we performed dynamic position and orientation characterization of the robotic systems. A laser tracker is used to measure the probe antenna movement relative to the antenna under test, this information is used to continually update the position and posture of the probe during scanning. We correlated the laser tracker data with the mmWave insertion phase to validate dynamic measurement position results at speeds up to 11 mm/s. We previously demonstrated spherical measurements with this system. The extrapolation measurements presented here require more stringent accuracies for pointing that general pattern analysis. I. INTRODUCTION Higher frequencies, multiple geometries, many antennas, multiple frequencies, rapid beam state changes, shorter testing requirements…. We are attempting to address many of these antenna testing issues simultaneously. There are requirements to test at higher frequencies for climate, security, and communications applications that need tighter tolerances on positioning, orientation and timing between system components than at lower frequencies. The ability to test multiple geometries such as planar scans at various orientations, or a spherical and extrapolation measurement with one setup, may allow for more rigorous testing with minimal increases in test time. We now see cell phones and spacecraft with many operational antennas that may need to be tested independently and having a test facility that can accommodate multiple testing requirements (NFC, Bluetooth, GPS, Cellular & Wi-Fi), might prove valuable. Finally, the ability to rapidly move probe antennas around test objects while maintaining orientation relative to the object under test may have applications in dynamic antenna testing and conformal testing such as medical and shielding applications. The use of coordinated robotics with multiple degrees of freedom and using laser-based positioning metrology equipment to guide and correct the scan geometries may offer solutions to these antenna testing issues. 1 US GOVERNMENT WORK - NOT SUBJECT TO COPYRIGHT II. OVERVIEW Previously, the Antenna Metrology project at NIST and others have presented results of mmWave spherical scanning using a six Degree-or Freedom (6DoF) robotic system [1,2]. The Configurable Robotic MilliMeter Antenna facility (CROMMA), fig. 1, has produced pattern and imaging measurement results from 60 to 225 GHz [1,3]. The major goal of this endeavor is to develop a configurable platform that can use different measurement geometries with minimal setup and alignment. The 6DoF positioning capabilities of the antenna under test (AUT) and probe stages, guided by the laser tracker, allow for correcting both pointing and positioning throughout the scan geometry with minimal alignment effort between the antenna and positioner. We continue to explore the ability of commercial-off-the- shelf (COTS) hardware to perform high accuracy testing. There is a lively debate on the practical ability to perform large volumetric scans using conventional mmWave measurement equipment [4,5]. Both positioning of the antennae and mmWave stability need to be determined to assess the quality of the entire measurement. If there is a considerable amount of variation in mmWave phase or amplitude (e.g. due to cable flexing or temperature shifts) then significant errors may be seen in the calculated antenna parameters. Similarly, if the quality of Figure 1. Major components of the Configurable MilliMeter Robotic Antenna Facility (CROMMA).