摘要:
The thickness of a web is measured by passing the web through the gaps of a loop-gap resonator. Changes in web thickness alter the resonant frequency of the resonator which is detected by a control circuit. Three embodiments of the invention are described, and in one embodiment, the moisture content of the web is also measured.
摘要:
A reusable self-supporting field director for use in a microwave oven is characterized by a plurality of vanes, each extending radially outwardly from a central axis. The vanes are supported in a slotted central support member. Each vane has a predetermined thickness dimension. Each vane comprises a substrate formed from an electrically non-conductive material having a predetermined coefficient of thermal expansion and an electrically conductive wrapper having a predetermined coefficient of thermal expansion that is different from the coefficient of thermal expansion of the substrate. The wrapper wraps the substrate so that a portion of the first and second major surfaces are covered and the radially inner end of each vane is wrapped by an electrically conductive material. The wrapper and the substrate are arranged in a laterally symmetric fashion so that thermal expansion effects due to heating are equalized across the thickness of each vane.
摘要:
A reusable self-supporting field director for use in heating an article in a microwave oven is characterized by a plurality of vanes, each vane extending radially outwardly from a central axis and being angularly adjacent to two other vanes. The vanes are attached to each other at their inner ends. Each vane has a substrate formed from an electrically non-conductive material and an electrically conductive wrapper that wraps the substrate so that a portion of the first and second major surfaces are covered and the radially outer end of each vane is wrapped by an electrically conductive material. The wrapper and the substrate are arranged in a laterally symmetric fashion so that thermal expansion effects due to heating are equalized across the thickness of each vane.
摘要:
A susceptor assembly comprises a generally planar susceptor having an electric field director structure mechanically connected thereto. The field director structure includes at least one, but more preferably, a plurality of two or more vanes mechanically connected to the susceptor. Each vane has a surface at least a portion of which is electrically conductive. The vane(s) are most preferably disposed substantially orthogonal to the planar susceptor. The connection may be either a fixed or a flexible articulating connection.In use, such as in the presence of a standing electromagnetic wave generated within a microwave oven, only an attenuated electric field component of the electromagnetic wave exists in a plane tangent to the surface of the vane in the vicinity of the conductive portion of the vane. Attenuation of the electric field component of the electromagnetic wave in the plane tangent to the surface of the vane resulting in enhancement of the component of the electric field substantially orthogonal to the conductive surface.Rotation of the susceptor assembly within the oven, or variation of the standing electromagnetic wave generated within the oven (as by a mode stirrer) results in a substantially uniform warming, cooking and browning effect on a food product placed on the planar susceptor.
摘要:
A susceptor assembly includes a generally planar susceptor having an electric field director structure mechanically connected thereto. The field director structure includes at least one, but more preferably, a plurality of two or more vanes mechanically connected to the susceptor. Each vane has a surface at least a portion of which is electrically conductive. The vane(s) are most preferably disposed substantially orthogonal to the planar susceptor. The connection may be either a fixed or a flexible articulating connection. In use, such as in the presence of a standing electromagnetic wave generated within a microwave oven, only an attenuated electric field component of the electromagnetic wave exists in a plane tangent to the surface of the vane in the vicinity of the conductive portion of the vane.
摘要:
A reusable self-supporting field director for use in heating an article in a microwave oven is characterized by a plurality of vanes, with each vane extending radially outwardly from a central axis.Each vane is angularly adjacent to two other vanes and is attached to each other at their inner ends. Each vane has a predetermined thickness dimension.Each vane each vane has a substrate formed from an electrically non-conductive material having a predetermined coefficient of thermal expansion, and an electrically conductive sheath having a predetermined coefficient of thermal expansion that is different from the coefficient of thermal expansion of the substrate. The sheath encases the substrate so that a portion of the first and second major surfaces and a portion of the first and second minor surfaces of each vane are covered by an electrically conductive material. The sheath and the substrate are arranged in a laterally symmetric fashion so that thermal expansion effects due to heating are equalized across the thickness of each vane.
摘要:
Methods of detecting an interface between first and second materials having different dielectric loss factors disposed in a stratified manner in a volume of materials using a sensing apparatus having a length of transmission line that includes an inner conductor surrounded by a dielectric material and at least one shielding conductor are disclosed. A predetermined number of sublengths of the inner conductor are exposed along the length of the transmission line, with adjacent sublengths of the exposed inner conductor being separated by shielded sublengths. In a first embodiment the sensing apparatus is excited by a radio frequency signal at a predetermined amplitude. The excited sensing apparatus is inserted into the volume of materials to a predetermined depth through the first layer and into the second layer. The signal transmitted through the sensing apparatus is detected and its attenuation measured. The interface between strata within the volume is identified based upon the attenuation of the radio frequency signal. In an alternate embodiment the sensing apparatus is excited by a radio frequency signal at a predetermined amplitude and progressively inserted into the volume of materials. The position of the sensing apparatus within the volume is tracked and the attenuation of the radio frequency signal is monitored as a function of insertion distance into the volume to detect first distance ranges having a substantial rate of change of attenuation and second distance ranges having substantially no change of attenuation. The location of the interface between strata within the volume is identified based upon differences in the rate of change in attenuation in adjacent first distance ranges.
摘要:
Disclosed are conductive polymeric materials comprising a resin-based structural material loaded with micron conductive fibers and/or micron conductive powders or to provide a conductive thermoplastic composition rather than an insulator. Also disclosed are antennas comprising the conductive thermoplastic compositions and methods for their fabrication.
摘要:
Methods of detecting an interface between materials having different dielectric loss factors using an apparatus having a transmission line including an inner conductor surrounded by dielectric and a shielding conductor are disclosed. Sublengths of inner conductor are exposed along the line, with adjacent sublengths being separated by shielded sublengths. In one embodiment the apparatus is excited by a signal and inserted into the materials to a predetermined depth. Signal attenuation is measured. The interface between strata is identified based upon signal attenuation. In another embodiment the apparatus is excited by a signal and progressively inserted into the materials. Apparatus position is tracked and t-he attenuation of the signal is monitored as a function of insertion distance to detect ranges having a substantial rate of change of attenuation and ranges having substantially no change of attenuation. The interface is identified based upon differences in the rate of change in attenuation.