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Real-time mm-Wave Imaging

Most imaging systems operate by detecting visible light or infrared radiation. These systems are generally passive, simply receiving visible light or infrared radiation from objects in the scene. In contrast, active systems illuminate the scene and then gather the reflected light or infrared radiation (e.g. a camera operating with a flash).

200GHz_receiver.gif
  The 200 GHz receiver showing (from right to left) two low noise amplifiers (LNAs), the subharmonically-pumped mixer and the driver amplifier for the local oscillator (LO)
CSIRO is conducting research into passive millimetre-wave imaging systems that produce a picture of a scene by detecting thermally generated millimetre-wave radiation. Systems using millimetre waves offer advantages over equivalent instruments detecting infrared and visible light because the millimetre-wave radiation can penetrate low visibility and obscuring conditions (caused for example by clothing, walls, clouds, fog, dust smoke and sandstorms).

Thus millimetre-wave imaging systems could be used in a range of important applications such as:

  • aids to aircraft landing;
  • collision warning in air, land and sea transport;
  • medical diagnostics (such as skin cancer detection);
  • mapping of hotspots in bushfires; and
  • covert and/or overt surveillance for intruders, contraband and weapons.

The imaging system under development at the CSIRO ICT Centre operates at frequencies near 200 GHz and is the subject of Australian and international patents. It uses two scanning antennas and our novel 200 GHz receivers to build up an image of the scene.

References

  • PCT Patent Application PCT/AU03/00897 (Australian Provisional Patent 2002950196)
    "Real-time Cross-correlating Millimetre-wave Imaging System". Inventors: John W. Archer, Oya Sevimli and Geoffrey C. James. PCT Publication Date: 22 January 2004; Provisional Patent Filed: 11 July 2002.
  • Archer J.W. and Shen M.G., "176-200 GHz receiver module using indium phosphide and gallium arsenide MMICs", Microwave and Optical Technology Letters, 43, 458-462 (2004).
  • Archer J.W. and Shen M.G., “W-band transmitter module using gallium arsenide MMICs”, Microwave and Optical Technology Letters, 42, 210-213 (2004).