Bulls-eye mid-frequency impedance probe
AssigneeThe Boeing Company
InventorArthur C. Lind
Life of this patent
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Abstract
The bulls-eye mid-frequency impedance probe has probe electrodes of a larger surface area that conform to the test surface to provide a very low impedance coupling between the probe and surface, unlike other open end coaxial probes. This probe provides accurate measurement of the dielectric properties of dielectric materials in the mid-frequency range of 10 MHz to 1 GHz on flat and curved solid surfaces, while conforming simple or complex curved surfaces by providing a resilient means between the probe contact surface and the probe box.
Claims11
A device for measuring the dielectric characteristics of material samples by contacting the surface of the samples, said device including a probe connected to a coaxial like by a connector having an outer conductor and a central conductor, wherein the probe comprises:
- a flexible contact surface comprising a flexible nonconductive substrate, an external conductor mounted upon the substrate and an internal conductor mounted upon the substrate, said external and internal conductors adapted to establish contact with and to conform to a shape of the samples, said external conductor being in electrical contact with the outer conductor of the connector and said internal conductor being in electrical contact with the central conductor of the connector;
- and
- a probe housing in physical contact to the substrate of the flexible contact surface.
A method for measuring dielectric characteristics of a solid material including the steps of:
- calibrating a signal processing device having an electrical line;
- measuring a complex impedance of a bulls-eye dielectric probe attached to the electrical line, said measurement of the complex impedance of the bulls-eye dielectric probe comprising:
- determining if the solid material is covered with a dielectric material;
- measuring the complex impedance of the bulls-eye dielectric probe based upon a dielectric spacer if the solid material is covered with a dielectric material;
- and
- measuring the complex impedance of the bulls-eye dielectric probe based upon the presence of an air gap if the solid material is free of dielectric material;
- measuring a complex impedance of the solid material;
- and
- calculating a dielectric constant of the solid material based on an analytical model of a coaxial cable radiating into semi-infinite space taking into account the complex impedance of the bulls-eye dielectric probe and the solid material.
Dependencies are inferred from the claim text.