The first video rate imagery from a proof-of-concept 32-channel 22 GHz aperture synthesis imager is reported. This imager has been brought into operation over the first half of year 2011. Receiver noise temperatures have been measured to be ~453 K, close to original specifications, and the measured radiometric sensitivity agrees with the theoretical predictions for aperture synthesis imagers (2 K for a 40 ms integration time). The short term (few seconds) magnitude stability in the cross-correlations expressed as a fraction was measured to have a mean of 3.45×10^-4 with a standard deviation of ~2.30×10^-4, whilst the figure for the phase was found to have a mean of essentially zero with a standard deviation of 0.0181°. The susceptibility of the system to aliasing for point sources in the scene was examined and found to be well understood. The system was calibrated and security-relevant indoor near-field and out-door far-field imagery was created, at frame rates ranging from 1 to 200 frames per second. The results prove that an aperture synthesis imager can generate imagery in the near-field regime, successfully coping with the curved wave-fronts. The original objective of the project, to deliver a Technology Readiness Level (TRL) 4 laboratory demonstrator for aperture synthesis passive millimetre wave (PMMW) imaging, has been achieved. The project was co-funded by the Technology Strategy Board and the Royal Society of the United Kingdom.

Date Published: 5 October 2011
PDF: 12 pages
Proc. SPIE 8188, Millimetre Wave and Terahertz Sensors and Technology IV, 818805 (5 October 2011); doi: 10.1117/12.899564

Published in SPIE Proceedings Vol. 8188:
Millimetre Wave and Terahertz Sensors and Technology IV
Keith A. Krapels; Neil Anthony Salmon; Eddie Jacobs, Editor(s)