On the in situ probe method for measuring the permittivity of materials at microwave frequencies

A technique to be used for determining in-vivo dielectric properties of materials at microwave frequencies is examined. The technique involves the use of an open-ended coaxial line as a sensor and models the coaxial aperture on the basis of a quasi-static analysis. This theory is discussed along with a correction method to account for system imperfections. With the proper choice of calibration standards and the use of the formulated admittance model, the complex permittivities of various unknowns can be determined over a wide range of frequencies. Experimental results are compared with data available in the literature. The technique limitations are also presented