410 results about "Frequency selectivity" patented technology

An electromagnetic resonance non-contact power transmission device includes a transmitter including a transmitter resonance element having a mechanism for discretely or continuously varying a resonant frequency, a transmitter excitation element coupled to the transmitter resonance element by electromagnetic induction, and an alternating current source for applying an alternating current at the same frequency as the resonant frequency to the transmitter excitation element, and a plurality of receivers each including a receiver resonance element having a specific resonant frequency, a receiver excitation element coupled to the receiver resonance element by electromagnetic induction, and an output circuit for outputting an electric current induced by the receiver excitation element. Electric power is transmitted selectively from the transmitter to any of the receivers having different specific resonant frequencies by changing the resonant frequency of the transmitter.

An electronic marker locator with a digital architecture for providing accurate and consistent estimation of the signal strength is presented. The marker locator includes a Digital Phase-Locked Loop (DPLL) structure. The electronic marker locator transmits known and adjustable frequency bursts corresponding to the markers to be located while synchronously capturing the signals returned from the markers. Because of the convergence properties of the DPLL, very consistent measurements of the reflected marker signal field strength are possible, resulting in both an improvement of maximum detection depth and depth accuracy. Further, the analog front-end hardware can be reduced, offering wider resistance to component tolerances, lower calibration and test times, and flexible frequency selectivity.

The radiation properties and wave guiding properties of frequency selective surfaces are used in conjunction with closely spaced antenna elements to fabricate antenna structures having adjustable radiation characteristics. The direction, magnitude, and polarization of radiation patterns for such antenna structures can be adjusted by varying the texture or patterning of layers of conducting material forming the frequency selective surfaces. The invention enables the fabrication of low profile antenna structures that can easily be conformed or integrated into complex surfaces without sacrificing antenna performance.

An antenna (100) for microwave radiation including a first horn (135) which includes a plurality of corrugations (150). At least one of the corrugations (150) is formed of a frequency selective surface (FSS) (138). The FSS has a plurality of FSS elements (305) coupled to at least one substrate (310). The substrate (310) can define a first propagation medium such that an RF signal having a first wavelength in the first propagation medium can pass through the FSS (300). The FSS (300) is coupled to a second propagation medium such that in the second propagation medium the RF signal has a second wavelength which is at least twice as long as a physical distance between centers of adjacent FSS elements (305).