Abstract
We have conceived a distributed thermal sensor based on the processing of the correlation function of the thermal noise emitted by the two ports of a small-size lossy transmission line in the microwave domain. The transducer is a lossy coplanar waveguide (LCPW) where losses are created by a thinning down of the central conductor. The two ports of the LCPW are connected to a microwave correlation radiometer. The knowledge of electrical characteristics of the LCPW and an original application of the Kalman filtering to the signals recorded as a function of the delay time of the correlator allow us to retrieve the temperature profile along an LCPW of length 2 cm deposited on alumina. In the present situation, due to a bandwidth limited between 2 and 4 GHz, the spatial resolution of temperature retrieval is about 4 mm. We show in this paper that the application of this processing to the radiometric data obtained with four radiometers of bandwidth 2 GHz, working at 3, 35, 60, and 94 GHz, the spatial resolution, with an LCPW of length 1 mm, becomes 200 μm. These interesting results lead to the definition of a synthetic bandwidth correlation radiometer, and to a demonstration of the feasibility of a new thermometric microsensor. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 94–100, 1998.
Published Version
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