부산대학교 도서관

This paper addresses microwave radiometry for passive noninvasive subcutaneous temperature measurements at a few centimeter depth. A correlation radiometer is designed from off-the-shelf parts to operate in the quiet 1.4-GHz band and tested on aqueous phantoms. The radiometer is first tested with a matched load, and then with a near-field planar probe antenna, both with two water phantoms of different volumes. The measurement resolution, sensitivity and long-term stability is quantified in terms of integration time for a simple three-point calibration. The lowest measured absolute error compared to a ground-truth thermocouple measurement is $\pm 0.25\,$K over one hour of data collection with a single calibration. Measurements show that an integration time >1 s results in an absolute error limited by the radiometer gain fluctuations. A probe on a seven-layer tissue stack is designed for measuring brain temperature.