Northrop Grumman Systems Corporation

Scott R Sorbel

Jonathon J Linch

Thomas E Keavney

Vincent M Ortiz

Owen Cupp

Katherine T Fountaine

Peter J Widmann

An absorption element for absorbing radiation incident on the element at a certain wavelength band. The element includes a surface defining a normal direction perpendicular to the surface. The element also includes an array of a plurality of spaced apart nano-pillars extending from the surface at an angle orientation other than the normal direction, which creates angular asymmetry so as to increase the element's absorption response in a particular direction. The nano-pillars are made of a suitable semiconductor material and have a size relative to the wavelength band to absorb the radiation. In one non-limiting embodiment, the nano-pillars are angled at 45&#xb0; relative to the normal direction and are cone-shaped to broaden their absorption capabilities.

Reflection and diffraction control with slanted semiconductor metamaterials

A metamaterial resonator structure having a size for resonating a predetermined frequency band. The resonator structure includes one or more dielectric slabs each having a top surface and a bottom surface. A conductive resonator element is configured on the top surface of each dielectric slab and has a crescent shape including a center portion and opposing rounded end portions defining a gap therebetween, where the center portion has a wider dimension then the end portions so that a width of the element gradually tapers from the center portion to the end portions, and where the conductive element has a diameter that is a fraction of a wavelength of the frequency band. Several dielectric slabs can be stacked on top of each other, where each slab has a different size and each conductive resonator element is a different size so that each resonator resonates a different portion of the frequency band.

Crescent ring resonator

An exemplary apparatus attenuates sound in a frequency range, e.g. audible frequencies. A resilient planar membrane has first and second honeycombs with unit cells attached to opposing sides of the planar membrane. Each unit cell has rigid walls extending perpendicular to the planar membrane. Buttresses are mounted inside the unit cells where dimensions of the buttresses result in an alteration of an attenuation versus frequency characteristic in the audible or other frequencies relative to an attenuation versus frequency characteristic without the buttresses.

Honeycomb unit cell acoustic metamaterial with in situ buttresses for tuned acoustic frequency attenuation

Systems and methods are provided for redirecting electromagnetic radiation around an object. A first assembly, including a first interior wall and a first exterior wall enclosing a propellant gas, substantially encloses the object. A first control system is configured to energize the propellant gas to provide a first volume of plasma and control an electron number density of the first volume of plasma. The electron number density of the first volume of plasma is selected to minimize reflection of the electromagnetic radiation from the first exterior wall. A second assembly includes a second interior wall and a second exterior wall enclosing a propellant gas and is substantially concentric with the first assembly and substantially encloses the object. A second control system is configured to energize the propellant gas to provide a second volume of plasma and control an electron number density of the second volume of plasma.

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Redondo Beach, CA, United States of America

Scott R Sorbel