Abstract: A method is provided for creating a spectral EM frequency to calculate the thickness of a material with unknown permeability and conductivity using metallic transparencies. The method comprises the steps of testing empirically to approximate the conductivity, testing empirically to approximate the permeability, creating a first set of electromagnetic waves adjacent to the material to be measured of a relatively low frequency, impinging the first set of electromagnetic waves on the material for saturating the material, creating a second set of electromagnetic waves having specific constant amplitude of a higher frequency than the first set of electromagnetic waves, the second set of electromagnetic waves for engaging the material and generating a sensing signal having modified characteristics, and receiving the sensing signal through the saturated material such that the modified characteristics of the sensing signal are processed to determine the thickness of the material.

Abstract: A device is provided for detecting the ullage level and flow in a vessel by detecting the presence of a solid or liquid material in proximity to a microwave detector. The device may be mounted to the side of the vessel or suspended inside the vessel so as to bring the microwave sensor into proximity with the surface of the contents of the vessel. A microwave bridge circuit may be used to detect a change in either the amplitude or phase of a signal reflected by the material within the vessel compared to a reference signal tuned to either the presence or absence of the anticipated solid or liquid material. In one embodiment, the reflected material signal is compared to the signal from a sample chamber containing the material to be detected. The device can reliably detect the level of multiple interfaces for various materials having distinct electric or magnetic properties.