Electromagnetic shielding and absorptive materials
AssigneeThe Pennsylvania State University
InventorsVijay K. Varadan, Vasundara V. Varadan
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Abstract
A material having a matrix and a plurality of inclusions which are chiral is effective as a coating to reduce incident reflections and absorptions of microwave frequency electromagnetic energy. The matrix can use an electrically conductive polymeric material as the base as well as any other low loss dielectric material. Chiral inclusions may be in the form of helices or any other small object displaying handedness. Moreover, it is possible to use electrically conductive polymeric materials by themselves as absorbers of electromagnetic energy. There are a variety of uses for these materials and the unique properties including gaskets for controlling the emission of microwave energy from electronic enclosures.
Claims21
A composite material comprising:
- a base material having a first dielectric constant which is complex in the frequency range of 150 megahertz to 100 gigahertz, and being at least partially opaque to electromagnetic energy with frequencies in the range of 150 megahertz to 100 gigahertz;
- and
- a chiral material having handedness, having a second dielectric constant which is different from the first dielectric constant, and being dispersed throughout the base material.
A composite material which is intrinsically anisotropic and structurally chiral comprising:
- a first layer of anisotropic material having an axis of anisotropy lying in the layer;
- a second layer of anisotropic material having an axis of anisotropy lying in the second layer, the axis of anisotropy for the second layer being positioned at a first predetermined angle from the axis of anisotropy for the first layer;
- and
- a third layer of anisotropic material having an axis of anisotropy lying in the third layer, the axis of anisotropy for the third layer being positioned at a second predetermined angle from the axis of anisotropy for the first layer, the second predetermined angle being larger than the first predetermined angle.
A gasket operable to shield electromagnetic wave propagation through a space defined between two surfaces, comprising an elongated resilient member having a characteristic transverse dimension, a length which substantially exceeds the characteristic transverse dimension, exhibiting transverse compressibility, and fashioned from a composite material including a substantially continuous phase having a plurality of chiral inclusions therein, each chiral inclusion having a characteristic size which is substantially smaller than the characteristic transverse dimension.
A gasket operable to shield electromagnetic wave propagation through a space defined between two surfaces, comprising an elongated resilient member having a characteristic transverse dimension, a length which substantially exceeds the characteristic transverse dimension, exhibiting transverse compressibility, and fashioned from a composite material including a substantially continuous phase of an electrically conductive polymeric material, the continuous phase having a plurality of chiral inclusions therein, each chiral inclusion having a characteristic size which is substantially smaller than the characteristic transverse dimension.
Dependencies are inferred from the claim text.