Abstract:
A touchscreen, now incorporated in most smartphones, tablets, laptops, and similar devices, presents an effective and transparent method to incorporate continuous active user verification schemes. The touchscreen element grid structure can be used to capture information, such as a set of one-dimensional time-varying signals produced as the user's finger moves past the grid intersections points. This information may be used to verify the user, or that a valid user currently has possession of the mobile device, even while the user is not consciously engaged in an active verification process. Further functions, such as habitual gesture recognition, can also be performed using the same grid outputs.
Abstract:
A prism coupled waveguide-fed solar collector array optimized for geometric fill factor. An integrated linear array of prisms is arranged with their input faces in a common plane. The exit faces of the prisms each feds a corresponding optical waveguide and detector.
Abstract:
The use of rectennas, or antenna-coupled rectifiers, using metal-insulator-metal tunnel diodes as rectifiers for energy conversion has been explored with more fervor recently, given the advances in nanotechnology fabrication and increased resolution of features. Some have made these devices from symmetric metals (e.g. Ni—NiO—Ni) and asymmetric metals (e.g. Al—AlOx/Pt), and have used deposited oxides as well as native oxides. One key to obtaining a highly asymmetric device with efficient current generation needed for high conversion efficiency is to instead use dissimilar metals and a thin reproducible oxide. The described method allows for a thin, reproducible native oxide of nickel be integrated with any antenna metal to overcome oxide surface roughness problems that typically hamper the practicality of these devices.
Abstract:
A stacked bow tie antenna array structure is placed within, for example a rectangular reflector. Spaces between the bow tie elements and the reflector are filled with close spaced conductive plates.
Abstract:
Techniques for implementing series-fed antenna arrays with a variable dielectric waveguide. In one implementation, coupling elements with optional controlled phase shifters are placed adjacent each radiating element of the array. To avoid frequency sensitivity of the resulting array, one or more waveguides have a variable propagation constant. The variable waveguide may use certain materials exhibiting this phenomenon, or may have configurable gaps between layers. Plated-through holes and pins can control the gaps; and/or a 2-D circular or a rectangular travelling wave array of scattering elements can be used as well.
Abstract:
Dispersive properties of a linear dispersive delay line are retained in a spiral configuration by constraining the radius of curvature depending on a desired propagation mode. The compact form factor spiral can be either a continuous spiral or a piecewise linear approximation. The spiral comprises a highly dielectric waveguide such as titanium dioxide or barium tetratitanate. Preferably, a spacer with a low dielectric constant and a microstrip are disposed on the top surface. The microstrip prevents attenuation of low frequencies, thereby increasing the operating frequency range. A second dielectric spacer and a second microstrip can be deposited on the bottom surface of the waveguide. Alternatively, the bottom surface of the waveguide can face a ground plane. The waveguide can be fed by horns or half-horns.
Abstract:
A solar energy collector includes a planar waveguide formed of multiple material layers having at least two different dielectric constants. Two or more dichroic filters disposed within the waveguide core, and two or more minors are also disposed within the waveguide core. At least one optical to electrical detector positioned in alignment with each of the dichroic filters, and at least one optical to electrical detector is aligned with each of the mirrors. The dichroic filter may be formed from a plurality of material layers.
Abstract:
System and methods for detecting substances such as explosives via the nuclear quadrupole resonance effect. We observe that the nuclear quadrupole resonances of explosives located within a cavity portal involve continuous Rabi transitions which are nonlinear processes since stimulated emission occurs. In other words, where there are no resonances caused by the presence of an explosive, high average power and low average power measurements should be identical. However, when resonances are stimulated by the system, the difference between these two conditions can be compared to determine a correction to measurements made when a person located in the cavity has explosive material on their person, without the need for separate empty portal or elaborate calibration procedures.
Abstract:
A cylindrically symmetric satellite antenna that provides directional and omnidirectional operating modes in a compact form factor. Feed points located at the top of the cylindrical structure provide increased platform isolation. Combining networks, disposed below or within the cylindrical structure, may be replaced with inexpensive baluns composed of coaxial line sections.