NEAR-FIELD MICROWAVE RADIOMETRIC WEIGHTING FUNCTIONS FOR MULTILAYEREDMATERIALS

A modal method is used for the determination of the near field weighti ng functions related to the power transmitted from a rectangular waveg uide aperture towards a lossy material and, by reciprocity, to the cor responding radiometric signals created by the thermal noise emission. This method is applied to homogeneous or multilayered material, such a s in microwave radiometry applied to medicine for non invasive thermom etry of the subcutaneous tissues. Rom the knowledge of the weighting f unctions, we propose a new definition for the volume of material coupl ed with the probe, as radiometric measurement terms. We present exampl es of such coupled volumes, as a function of frequency or size of the probe.