Method and apparatus for the testing of dielectric materials
First Claim
1. A method for the nondestructive testing of a sheet of dielectric material having opposite faces conductively surfaced and edges of exposed dielectric, comprising:
- determining, by means of injected microwave energy passed through the dielectric sheet, respective values related to the average dielectric constant of the sheet along a plurality of paths in the plane of the sheet, said paths comprising a first group of mutually parallel paths and a second group of mutually parallel paths oriented to intersect the paths of the first group; and
comparing said values with one another, thereby identifying variations in dielectric constant within said sheet.
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Accused Products
Abstract
Method and apparatus for the nondestructive testing of metal-clad microwave circuit boards to determine dielectric constant variations within the dielectric sheets of such boards. The method involves using injected microwave energy to measure values related to the average dielectric constant along a plurality of paths in the plane of the sheet. The paths are divided into two intersecting groups, with each path being parallel to the members of its own group. Resulting values are then compared in order to identify dielectric constant variations within the sheet. Measurements may be made by means of phase delay or amplitude/resonance frequency techniques. A preferred apparatus for phase delay measurement is disclosed which includes means for making a simultaneous phase delay measurement along a reference air path.
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Citations
27 Claims
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1. A method for the nondestructive testing of a sheet of dielectric material having opposite faces conductively surfaced and edges of exposed dielectric, comprising:
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determining, by means of injected microwave energy passed through the dielectric sheet, respective values related to the average dielectric constant of the sheet along a plurality of paths in the plane of the sheet, said paths comprising a first group of mutually parallel paths and a second group of mutually parallel paths oriented to intersect the paths of the first group; and comparing said values with one another, thereby identifying variations in dielectric constant within said sheet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An apparatus for the nondestructive testing of a sheet of dielectric material having opposite faces conductively surfaced and edges of exposed dielectric, comprising:
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a signal generator for producing microwave energy; a transmitter connected to receive microwave energy from said signal generator and adapted to radiate said microwave energy as a directional beam, said transmitter being positionable adjacent an edge of the sheet such that said beam enters the sheet at said edge and travels through the sheet along a path in the plane of the sheet; a microwave receiver; means for positioning the microwave receiver a variable distance from the transmitter, such that the microwave receiver is positionable adjacent an edge of the sheet to receive said beam as its exits from the sheet; means for directing a portion of said microwave energy along an air path whose length is in a fixed ratio to the length of the path through the sheet; and means for comparing the phase delay of the microwave energy passing through the sheet with the phase delay of the microwave energy passing along the air path. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification