Passive millimeter-wave camera images: current and future

摘要

Abstract: Rapidly improving technology is transitioning current laboratory images into reality with fielded systems expected within two years. W-band radiometers have been shown to be effective in detecting metallic and nonmetallic weapons concealed under heavy garments in both outdoor and indoor situations. Systems that are in development will provide real-time display and weapon detection in controlled situations. The incorporation of technology improvements that have already been demonstrated will double the sensitivity and provide affordable systems with rapid scanning for general use. Lockheed Martin and Intelligent Machine Technology are working to build a demonstration system for the Department of Justice and the Air Force Research Laboratory that can be extended to take advantage of rapidly moving semiconductor improvements. Our current radiometer modules use a PIN switch for the Dicke calibration function followed by multiple low noise amplifier stages, a Schottky detector and a video amplifier. Sensitivity of such modules if primarily a function of the insertion loss and noise figure of the front end MMEC circuits. Processing improvements at Lockheed Martin and refined chip design will result in a 3-db improvement in the effective noise figure within the next year. Imaging is also greatly improved by achieving greater effective bandwidth and higher operating frequency. Whereas present modules operate from 80 to 90 G Hz, MMEC improvements will provide for operation up to 140G Hz with a doubling of the bandwidth in the near term. Receiver operation up to 540G Hz has also been demonstrated at other labs.!0