Abstract:
PROBLEM TO BE SOLVED: To provide a probe sensor of a compact device for remotely detecting the presence of chemical or biological agents through the use of an electromagnetic microcavity element or an array or assembly of microcavity elements. SOLUTION: The sensor is provided with electromagnetic microcavities. An agent to be detected passes through the microcavities and is adsorbed and/or absorbed by the microcavities to modify the electromagnetic field inside the microcavities. After the agent has been adsorbed and/or absorbed, a probe beam is applied to the microcavities. The change of electromagnetic field is detected by a detector, and the frequency of the probe beam at which the resonance is observed is indicative of a particular agent being present. A method for detecting chemical and/or biological compounds uses the sensor. COPYRIGHT: (C)2008,JPO&INPIT
Abstract:
A multiple band reconfigurable reflecting antenna array and method for mulitple band operationand beam steering. An array of dipole antennas is disposed on a multiple band high impedancesurface. The antenna array is reconfigured by changing the length of the dipole elements, tothereby change the dipoles resonant frequency. At a given frequency band, small changes in dipole length allow to steer the reflected beam in the selected direction; whether large changes indipole length permit to switch the operating frequency band. A method of broadening thebandwith of a high impedance surface is also exposed.
Abstract:
A steerable antenna and method of steering a radio frequency wave receiving by and/or transmitting from the antenna. The antenna includes a tunable high impredance surface and at least one end-fire antenna disposed on said surface. The method includes varying the impedance of the tunable high impedance surface.
Abstract:
A crossed slot antenna, a method of fabricating same and a method of designing same. The antenna includes a cavity structure having conductive material on opposed surfaces thereof; and two slots in said conductive material, the slots having slightly different lengths and intersecting each other at or close to a 90 degree angle.
Abstract:
A tuneable impedance surface for steering and/or focusing a radio frequency beam. The tunable surface comprises a ground plane; a plurality of elements disposed a distance from the ground plane, the distance being less than a wavelength of the radio frequency beam; and a capacitor arrangement for controllably varying the capacitance of adjacent top plates, the capacitor arrangement including a dielectric material which locally changes its dielectric constant in response to an external stimulus.
Abstract:
A directive antenna and method of directing a radio frequency wave received by and/or transmitted from the antenna. The antenna preferably includes a high impedance surface with a plurality of antenna elements disposed on said surface, a plurality of associated demodulators and power sensors and a switch. A Vivaldi Cloverleaf antenna is disclosed.
Abstract:
A polarization converting surface for reflecting impinging radio frequency waves. The surface includes a ground plane and a plurality of elements disposed in an array a distance from the ground plane. Each element is preferably connected to the ground plane by a conductor, the array of elements having two major axes associated therewith. The elements have a first bandwidth corresponding to a first range of frequencies were a first reflection phase falls between -pi/2 and +pi/2 in a first one of said two major axes and a second bandwidth corresponding to a second range of frequencies were a second reflection phase falls between -pi/2 and +pi/2 in a second one of said two major axes. The first and second bandwidths partially overlap and preferably an upper half of one of the bandwidths overlies a lower half of the other one of the bandwidths.
Abstract:
An antenna for receiving and/or transmitting a radio frequency wave. The antenna includes a plurality of flared notch antennas disposed adjacent to each other and arranged such that their directions of maximum gain point in different directions, each of the flared notch antennas being associated with a pair of radio frequency radiating elements and wherein each radio frequency radiating element serves as a radio frequency radiating element for two different flared notch antennas and has a gap therein having a length equal to approximately one quarter wavelength of the radio frequency wave.