Microwave Images of Sub-Surface Utilities in an Urban Environment

The principle of identifying concealed object shapes by microwave holography has become established in recent years. An important application would be the imaging of buried cables and pipes if the problem of the high attenuation of ground and the strong surface return could be overcome. It is shown in the present work that a synthetic aperture imaging technique based on polarization discrimination mitigates these problems. The technique has been tested in the real urban environment by producing an image of a gas pipe at depths up to 0.25m below the ground surface. An area of ground is scanned with 0.95GHz radiation, the backscatter is recorded in complex form, and the data is computer-processed to produce focussed images on a 16-level TV display.