A 190GHz active millimeter-wave imager

Abstract

The design and testing of a 190 GHz imaging system is presented. The system features two beam-scanning antennas; the first transmits a horizontal fan beam and the second receives a vertical fan beam. By correlating the signals from the antennas, an estimate of the millimeter-wave reflectivity at the intersection of the fan beams is obtained. Each fan beam is scanned by rotating a small subreflector within the antenna; this simple rotation motion allows rapid scanning. The system is portable, currently approximately 0.6m × 0.6m × 2m high; the key size constraint is imposed by the 450 mm aperture length of the antennas. The imager has an angular resolution of 0.25° and a field of view of 14° × 14°, resulting in a raw image of approximately 50 × 50 pixels. The raw image is processed using super-resolution techniques. Images will be presented which show the capability of the system to image metallic and ceramic objects beneath clothing. These images were obtained by illuminating the scene with signals from a frequency-doubled Gunn oscillator. While this paper focuses on active imaging, the system can also operate in passive mode with reduced sensitivity.

Near range MMW synthetic aperture radiometer 3D passive imaging

“…1. In recent years, near range MMW-SAR passive imaging technology has been developed, and imaging prototypes have been reported by Japanese NEC Corp. [9] and Australian ICT center of CSIRO [10]. Also, there is similar research on Terahertz in NJIT of USA [11].…”

Terahertz and Millimetre Wave Imaging with a Broadband Josephson Detector Working above 77 K

“…Active and passive mm-wave imaging [1][2][3] has been widely used in the area of security screening due to its unique combined features of penetration and resolution; and in astrophysics due to its sensitivity to emissions from astronomical objects. Infrared (IR) imaging of black body radiation is also a well developed technology.…”