An assembly formed by additive manufacturing comprises a top face sheet, a bottom face sheet, and a core structure between the top face sheet and the bottom face sheet, the core structure comprising a plurality of cells, wherein structural elements of the core structure defining the plurality of cells exhibit at least one electrical property in at least one direction varying from at least one electrical property in a second, different direction and at least one structural property in at least one direction varying from at least one structural property in a second, different direction, wherein at least a portion of the structural elements comprises a radar absorbing structure, the structural elements comprising a matrix material and at least one additive dispersed in or on the matrix material. Related radar absorbing structures and related methods of fabricating the radar absorbing structures are also disclosed.

To provide a transmission-type electromagnetic-wave absorber that can satisfactorily absorb electromagnetic waves of high frequencies in or above the millimeter-wave band while reducing the reflection of electromagnetic waves on the surface of the absorber. The transmission-type electromagnetic-wave absorber includes an electromagnetic-wave absorbing layer 1 containing a magnetic iron oxide 1a that magnetically resonates at a frequency in or above the millimeter-wave band and a binder 1b containing an organic material. The real part of the complex relative permittivity of the electromagnetic-wave absorber is 5.5 or less at 1 GHz.

An electronic module that comprises a housing; a cover that is disposed over the housing to define an interior; and one or more electronic components positioned within the interior is provided. At least a portion of the housing, cover, or both contain a polymer composition that exhibits an in-plane thermal conductivity of about 1 W/m-K or more as determined in accordance with ASTM E 1461-13 and an electromagnetic shielding effectiveness of about 20 dB or more as determined at a frequency of 1 GHz in accordance with EM 2107A.

An antenna for a ground-penetration radar system is disclosed. The antenna has a housing that defines a cavity. A radiator is located on a surface of a planar substrate within the cavity. A wear-block is located between the radiator and the opening to the cavity for providing mechanical protection to the radiator. An absorber assembly is located on an opposite side of the radiator from the opening. The absorber assembly comprises a microwave absorber and a first dielectric layer. The first dielectric layer is located between the radiator and the microwave absorber.

An apparatus is described that selectively absorbs electromagnetic radiation. The apparatus includes a conducting surface, a dielectric layer formed on the conducting surface, and a plurality of conducting particles distributed on the dielectric layer. The dielectric layer can be formed from a material and a thickness selected to yield a specific absorption spectrum. Alternatively, the thickness or dielectric value of the material can change in response to an external stimulus, thereby changing the absorption spectrum.

A metallic component including NiCr and having a skin depth of greater than or equal to 1.0 m in a frequency range from 20-40 GHz, as calculated by: $=\sqrt{\frac{2}{\left(2f\right)\left({}_0{}_r\right)}}503\sqrt{\frac{}{{}_{r}f}}.$ In this equation, is skin depth in meters (m); is resistivity in ohm meter (.Math.m); f is frequency of an electromagnetic radiation in hertz (Hz); .sub.0 is permeability; and .sub.r is relative permeability of the NiCr metallic material. The metallic component may be a discrete metallic particle or a layer in a multilayer thin film.

A metallic component including a metallic material and having a skin depth of greater than or equal to 1.0 m in a frequency range from 20-40 GHz, as calculated by: $=\sqrt{\frac{2}{\left(2f\right)\left({}_0{}_r\right)}}503\sqrt{\frac{}{{}_{r}f}}.$
In this equation, is skin depth in meters (m); is resistivity in ohm meter (.Math.m); f is frequency of an electromagnetic radiation in hertz (Hz); .sub.0 is permeability; and .sub.r is relative permeability of the metallic material. The metallic component may be a discrete metallic particle or a layer in a multilayer thin film.

A method for providing control of surface waves propagating on a surface includes forming a surface treatment on the surface, wherein the surface treatment is configured to achieve a tensor surface admittance distribution matrix on the surface determined according to a modified transformation electromagnetics (tEM) equation.

The present invention provides an electromagnetic wave absorbing sheet which contains conductive short fibers and an insulating material, and which exhibits particularly high radio wave absorbing properties in one direction.

A multilayer thin film that reflects an omnidirectional structural color having a reflective core layer comprising a metallic material, a second layer extending across the reflective core layer, a third layer extending across the second layer, and an outer layer extending across the third layer. The multilayer thin film reflects a single narrow band of visible light that is less than 30 measured in Lab color space when viewed from angles between 0 and 45, and the reflective core layer has a skin depth of greater than or equal to 1.0 m in a frequency range from 20-40 GHz, as calculated by:

[00001]$=\sqrt{\frac{2}{\left(2f\right)\left({}_0{}_r\right)}}503\sqrt{\frac{}{{}_{r}f}},$

is skin depth in meters (m); is resistivity in ohm meter (.Math.m); f is frequency of an electromagnetic radiation in hertz (Hz); .sub.0 is permeability; and .sub.r is relative permeability of the metallic material.