THERMOMETRY ON LOSSY COPLANAR LINES BY MICROWAVE CORRELATION RADIOMETRY

The principle of this original thermal sensor is the same as for inter ferometric synthetic aperture microwave radiometry [1], presently used for remote sensing. Our aim is to apply this process for short-range thermometry. It is well known that a dissipative material creates a no ise signal depending on its temperature. The correlation function of s uch noise signals exhibits significant values if both contributions to the correlation product are sufficiently correlated. For example, we consider both ports of a lossy transmission line to be connected to a wideband microwave correlation radiometer. If a hot spot is located on the line, the output signal is maximal if the delay line of the corre lator compensates the distance of the hot spot with respect to the cen tre of the line. Then, it is possible to evaluate the position and the intensity of the corresponding hot spot. Recent experimental studies made with microstrip lines and coplanar waveguides have shown that a t emperature retrieval is possible in a more complicated temperature dis tribution by a Kalman filtering of the correlation function of the noi se. The study of other passive dissipative networks is probably also p romising.