Field Correlation Radiometry for Improved Spatial Focusing in Internal Temperature Sensing

Microwave radiometry has been demonstrated as a viable method for non-invasive measurements of internal body temperature, including that of the brain. Existing approaches use a single near-field antenna placed on the skin at low microwave frequencies where the sensing depth is on the order of centimeters. Such a near-field antenna integrates the temperature over a relatively large volume. Here we introduce a generalized theory for near field correlation radiometry of multiple radiometers for improving spatial resolution. Results of a numerical study for measuring core brain temperature are shown using two 1.5 GHz near-field antennas placed on the head, with a comparison to the single-antenna case.