Abstract: A low-profile multi-band antenna module includes first and second antennas that transmit first and second radio frequency (RF) signals in a first and second RF band, respectively. A first RF multiplexer combines the first and second RF signals for transmission. The first antenna, second antenna, and first RF multiplexer are arranged on a panel. A transmission line communicates with the first RF multiplexer and transmits the first and second RF signals. A second RF multiplexer communicates with the transmission line and separates the first and second RF signals. At least one of the antennas communicates with an amplifier. The transmission line supplies direct current (DC) power to the amplifier. The first and second antenna are arranged on the panel in an orientation that minimizes electrical interference between the first and second antenna. A combination of the first and second antenna minimizes interference between the first and second RF band.

Abstract: A circularly polarized antenna system having improved axial ratio is disclosed. The antenna system comprises a circularly-polarized antenna, and a high-impedance buffer surface, surrounding the circularly polarized antenna, and disposed between the circularly polarized antenna and a ground plane. The width of the high-impedance buffer surface between the circularly-polarized antenna and the ground plane is selected to achieve an H-plane radiation pattern substantially identical to an E-plane radiation pattern over a desired scan angle.

Abstract: A radio frequency aperture comprising a plurality of insulating layers disposed in a stack, each layer including an array of conductive regions, the conductive regions being spaced from adjacent conductive regions. Also disclosed is method of bending or steering radio frequency waves impinging an antenna. The method includes disposing a plurality of insulating layers arranged in a stack between a source of the radio frequency waves and the antenna, wherein each insulating layer includes an array of conductive regions, the conductive regions being spaced from adjacent conductive regions and forming capacitive elements. The capacitance of the capacitive elements in the plurality of insulating layers is adjusted as a function of their location in the plurality of insulating layers.

Abstract: A compact sensor for detection of chemical and/or biological compounds in low concentration. The sensor comprises electromagnetic microcavities. The agent to be detected passes the microcavities, is absorbed and/or absorbed by the microcavities, and modifies 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 the 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 using the sensor.

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 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 high impedance (Hi-Z) wire effectively transparent to electromagnetic radiation polarized in the direction of the wire, within an operating frequency band. The Hi-Z wire is sheathed with a thin layer of resonant structures that are small compared to the wavelength, and behave as a kind of photonic band gap (PBG) material. A frequency-selective polarizer comprising a plurality of Hi-Z wires disposed parallel to one other in a grid. A wire grid reflector that enables stepwise phase control of the reflected wave and focusing of radiative power, the reflector comprising Hi-Z wires interspersed with conventional wires disposed parallel to one another in a grid.

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 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 at least selected ones of adjacent elements. A method of tuning the high impedance surface allows the surface to mimic, for example, a parabolic reflector or a diffraction grating.

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.

Abstract: A steerable antenna and method of steering a radio frequency wave received by and/or transmitted from the antenna. The antenna includes a tunable high impedance 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 high impedance surface having a reflection phase of zero in multiple frequency bands and a method of making same. The high impedance surface includes a ground plane; a plurality of conductive plates disposed in a first array spaced a distance from the ground plane, the distance being less than a wavelength of the radio frequency beam, said first array having a first lattice constant; and a plurality of conductive elements associated with said plurality of conductive plates, said plurality of conductive elements defining a second array, said second array having a lattice constant greater than the lattice constant of the first array.

Abstract: A tuneable impedance surface for steering and/or focusing a radio frequency beam. The tunable surface comprises a ground plane; a first plurality of elements disposed in an array a first distance from the ground plane, the distance being less than a wavelength of the radio frequency beam; and a second plurality of elements disposed in an array a second distance from the ground plane, the second plurality of elements be moveable relative to the first plurality of elements.

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 −&pgr;/2 and +&pgr;/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 −&pgr;/2 and +&pgr;/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: A compact sensor for detection of chemical and/or biological compounds in low concentration. The sensor comprises electromagnetic microcavities. The agent to be detected passes the microcavities, is absorbed and/or absorbed by the microcavities, and modifies 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 the 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 using the sensor.

Abstract: A multiple band reconfigurable reflecting antenna array and method for multiple band operation and beam steering. An array of dipole antennas is disposed on a multiple band high impedance surface. The antenna array is reconfigured by changing the length of the dipole elements, to thereby 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 in dipole length permit to switch the operating frequency band. A method of broadening the bandwidth of a high impedance surface is also exposed.

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 method and apparatus for providing a high impedance structure or surface comprising at least one electrically conductive wire forming at least one elongate wire spiral, the at least one elongate wire spiral being defined by a plurality of spirals of said at least one wire, the spirals having a pitch and being spaced apart along a major axis of said elongate wire spiral; and an arrangement for varying the pitch of the spirals of said at least one wire to thereby tune the impedance of said tuneable impedance structure. An embodiment useful as an antenna aperture to steer a radio frequency beam having two different polarizations is disclosed.