摘要:
A waveguide filter (22,24) is incorporated into a cavity resonator (20) for a free-electron laser or the like by coating a material layer (24) on the inner peripheral surface of a hollow waveguide member (22). A high pass filter configuration is provided when the conductivity of the material layer (24) is higher than that of the waveguide member (22), such that electromagnetic signals having wavelengths longer than the skin depth of the material layer (24) pass into and are affected by the lower conductivity waveguide member (22). Reversing the conductivities produces a low pass filter configuration in which signals having wavelengths shorter than the skin depth are affected by the material layer (24). A bandpass filter configuration is provided by adding an additional material layer (32) of low conductivity to a high pass filter, whereas a band exclusion filter configuration is produced by adding an additional material layer (32) of high conductivity to a low pass filter.
摘要:
An electromagnetically operational micro-truss structure and methods are disclosed. A micro-truss structure comprises a grid of interlocking elements, and a metallic coating selectively coats the grid. The metallic coating is configured to resonate an electromagnetic energy.
摘要:
A transmission line feed for a surface wave medium having a dielectric substrate with an array of electrically conductive patches formed thereon. The transmission line feed includes a microstrip substrate, the microstrip substrate having a first permittivity which is lower than a second permittivity of the dielectric substrate of the surface wave medium, the microstrip substrate abutting against the dielectric substrate of the surface wave medium; a tapered microstrip disposed on the microstrip substrate, the tapered microstrip tapering from a relatively narrow end to a relatively wide end, the relative wide end terminating where the microstrip substrate abuts against the surface wave substrate; and an adapter for coupling a transmission line to the relatively narrow end of the tapered microstrip.
摘要:
A material of variable emissivity includes a first metallic layer having a first aperture, a second metallic layer having a second aperture, and a variable dielectric layer interposed between the first metallic layer and the second metallic layer.
摘要:
A dielectric artificial impedance surface antenna (DAISA) including a dielectric with a thickness, the dielectric thickness varying to provide a modulated impedance to a signal traversing the dielectric, the dielectric having a first surface, and a second surface opposite the first surface.
摘要:
A tunable impedance surface, the tunable surface including a plurality of elements disposed in a two dimensional array; and an arrangement of variable negative reactance circuits for controllably varying negative reactance between at least selected ones of adjacent elements in the aforementioned two dimensional array.
摘要:
A resistively heated diesel particulate filter (DPF). The resistively heated DPF includes a DPF having an inlet surface and at least one resistive coating on the inlet surface. The at least one resistive coating is configured to substantially maintain its resistance in an operating range of the DPF. The at least one resistive coating has a first terminal and a second terminal for applying electrical power to resistively heat up the at least one resistive coating in order to increase the temperature of the DPF to a regeneration temperature. The at least one resistive coating includes metal and semiconductor constituents.
摘要:
In various embodiments, an adaptive spectral surface is provided including an upper layer having a frequency selective surface, a lower layer being at least partially reflective, and an active dielectric material layer therebetween. The active dielectric material may include a dielectric material with an adjustable permittivity, permeability, or thickness. The active dielectric material may be a dielectric material adapted to change its dielectric constant in response to at an applied electric field, an applied magnetic field, or/and thermal stimulus. Some embodiments allow shifting of the resonance of the spectral absorptive/reflective emissions of the adaptive spectral surface. Some embodiments allow modification of the electromagnetic signature of an adaptive spectral surface apparatus.
摘要:
A material of variable emissivity includes a first metallic layer having a first aperture, a second metallic layer having a second aperture, and a variable dielectric layer interposed between the first metallic layer and the second metallic layer.
摘要:
A method of and apparatus for modulating an optical carrier by an incident electromagnetic field. The electromagnetic field propagates in a dielectric-filled transverse electromagnetic waveguide, At least one slice of an electro-optic material is disposed in the dielectric-filled transverse electromagnetic waveguide, the electro-optic material in the dielectric-filled transverse electromagnetic waveguide having at least one optical waveguide therein which has at least a major portion thereof guiding light in a direction orthogonal with respect to a direction in which the dielectric-filled transverse electromagnetic waveguide guides the incident electromagnetic field. Light is caused to propagate in the at least one optical waveguide in the at least one slice of an electro-optic material in the dielectric-filled transverse electromagnetic waveguide for modulation by the incident electromagnetic field.