Subcutaneous fat thickness measurement using rectangular waveguide by approximation of waveguide admittance to plane wave admittance

In this paper, we propose a fast algorithm to measure skin and subcutaneous fat thickness. To reduce a computational complexity in mode matching method, an aperture admittance of a waveguide attached to human body which consists of materials with high dielectric constant and loss is approximated to the characteristic admittance of the plane wave. In order to estimate the thickness of skin and subcutaneous fat, maximum likelihood estimation (MLE) method is used. For accurate estimation, the permittivities of pork composed of skin, fat and muscle were measured by open ended coaxial cable. The proposed algorithm is verified by measuring the thickness of skin and fat and comparing the result with ultrasound scanning.