Use of a microwave cavity for sensing dielectric properties of arbitrarily shaped biological objects

A rectangular waveguide resonator operating in the H/sub 105/ mode at 3.2 GHz is used in determining the change in resonant frequency, Delta F, and the Q factor of the cavity, Delta T, when measured with and without single corn kernels of various shapes and dimensions. By measuring those variables for a kernel oriented in two positions differing by a 90 degrees rotation with respect to the maximum E-field vector, the average values of Delta F and Delta T are found to be independent of shape. The ratio Delta F/ Delta T is independent of size and is a function of the material properties ( epsilon '-1)/ epsilon ". This function is shown to be related to the material density, moisture content, or other characteristics when all other properties except the one selected remain unchanged.<
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