A W-Band Imaging Radiometer Measurement in Near Field of Antenna

Abstract

Radiometers are able to detect the hidden object such as weapons in the situation, where the others sensor systems failed. The ability of object detection depends on the radiometric contrast of measured object and parameters of the radiometric sensor system. For experimental measurements, a direct detection radiometric module in W-band and a horn antenna was used. The paper deals with a measurement of radiometric image of objects in near field of radiometer antenna. As a measured object, the bakelite plate with a square shaped aluminum foil located in the mid-point was chosen. It provides us the object with high radiometric contrast suitable for testing of radiometric sensor system. In the paper, there is also description of basic low-frequency circuitry design of radiometer, which has ultralow noise and high gain performance, too. The main part of the paper describes outcomes of measurements which were realized in order to verify parameters of designed radiometer low-frequency circuitry. Radiometric image was scanned by inverse synthetic aperture technique, that means that a radiometer antenna was static and a sensed object was moving in $\boldsymbol{x}$ and $\boldsymbol{y}$ axis in front of the antenna.