NIST developed three switched-array channel sounders at mmWave frequencies that can precisely measure radio propagation channel characteristics such as path loss, small-scale fading, delay dispersion, absolute delay, angle-of-arrival, and Doppler power spectrum. On the receiver side, every system is equipped with a custom-designed scalar-feed-horn antenna array with 16 elements featuring an omnidirectional azimuthal field-of-view and enabling 3D angle-of-arrival extraction. The channel sounders at 28.5 and 83.5 GHz have a single omni-directional antenna on the transmitter side, while the 60.5 GHz channel sounder has an antenna array on the transmitter side as well, adding capabilities of 3D angle-of-departure extraction.
The system architecture of our switched-array channel sounders and calibration techniques can be found in the references below:
 R. Sun, P.B. Papazian, J. Senic, Y. Lo, J.-K. Choi, K.A. Remley, C. Gentile, “Design and Calibration of a Double-directional 60 GHz Channel Sounder for Multipath Component Tracking,” IEEE European Conf. on Antennas and Propagation, 2017. (BEST PAPER AWARD in measurements) https://ieeexplore.ieee.org/document/7928270
 P. B. Papazian, C. Gentile, K.A. Remley, J. Senic, and N. Golmie, “A Radio Channel Sounder for Mobile Millimeter-Wave Communications: System Implementation and Measurement Assessment,” IEEE Transactions on Microwave Theory and Techniques, vol. 64, no. 9., pp. 2924-2932, Sept. 2016. https://ieeexplore.ieee.org/document/7534832
 P. B. Papazian, J.-K. Choi, J. Senic, P. Jeavons, C. Gentile, N. Golmie, R. Sun, D. Novotny, K.A. Remley, “Calibration of Millimeter-wave Channel Sounders for Super-resolution Multipath Component Extraction,” IEEE European Conf. on Antennas and Propagation, April 2016. https://ieeexplore.ieee.org/document/7481704