An antenna assembly may include an antenna element, a radome structure disposed proximate to the antenna element and including a plurality of plasma elements, a driver circuit operably coupled to the plasma elements to selectively ionize individual ones of the plasma elements, and a controller. The controller may be operably coupled to the driver circuit to provide control of plasma density of the individual ones of the plasma elements. The plasma elements may include respective enclosures. At least some of the enclosures may have at least two peripheral edge surfaces substantially fully contacted by corresponding peripheral edge surfaces of adjacent enclosures at at least one section along a longitudinal length thereof.

The present invention is directed at a waveguide antenna for microwave enhanced combustion of a previously ignited fuel-air mixture. The waveguide antenna has a thermal conductivity of at least 150 W/mk and can be formed from a metallic shell with a ceramic core.

An antenna comprising: a radio frequency (RF) coupler; a transceiver communicatively coupled to the RF coupler; a laser configured to generate a plurality of femtosecond laser pulses so as to create, without the use of high voltage electrodes, a laser-induced plasma filament (LIPF) in atmospheric air, wherein the laser is operatively coupled to the RF coupler such that RF energy is transferred between the LIPF and the RF coupler; and wherein the laser is configured to modulate a characteristic of the laser pulses at a rate within the range of 1 Hz to 1 GHz so as to modulate a conduction efficiency of the LIPF thereby creating a variable impedance LIPF antenna.

Various methods, apparatus, devices and systems are provided for electrically short antennas for efficient broadband transmission. In one example, among others, a system includes a segmentally time-variant antenna and a segment controller that can control conductivity of individual segments of the segmentally time-variant antenna. The conductivity of the individual segments is modulated to allow a pulse to propagate from the proximal end to the distal end of the segmentally time-variant antenna and impede a reflection of the pulse from propagating back to the proximal end of the segmentally time-variant antenna. In another embodiment, a method includes injecting a pulse at a first end of a segmentally time-variant antenna and modulating conductivity of individual segments to allow the pulse to propagate to a second end of the segmentally time-variant antenna and impede a reflection of the pulse from propagating back to the first end.

A sealed case (6) includes a first electrode (4) and a second electrode (5). The maximum size of each of these electrodes and a distance between them are equal to or smaller than one tenth the wavelength of a signal of interest. The sealed case (6) is configured such that the internal gas becomes a plasma state. The second electrode (5) is connected to a first conductor (1), and the first electrode (4) is connected to a second conductor (2) disposed to be perpendicular to the first conductor (1).

Aspects and embodiments relate to a plasmonic metamaterial structure, applications and devices including that plasmonic metamaterial structure, and a method of forming that plasmonic metamaterial structure. Aspects and embodiments provide a plasmonic metamaterial structure which comprises: a plurality of optical antenna elements. The plurality of optical antenna elements comprise: a first electrode, a second electrode and a plasmonic nanostructure element located between the first and second electrode to form an electron tunnelling junction between the first and second electrodes. The plurality of optical antenna elements are configured such that the electromagnetic field of one optical antenna element spatially overlaps that of adjacent optical antenna elements and adjacent optical antenna elements are electromagnetically coupled to allow the plurality of optical antenna elements to act as a plasmonic metamaterial. Aspects and embodiments also provide devices including that plasmonic metamaterial structure, and a method of forming that plasmonic metamaterial structure. Aspects and embodiments recognise that the sensitivity of an electron tunnelling junction, coupled with provision of a plurality of optical antenna elements may provide a practical structure which can provide sensing platforms, modulation, light source and nanoscale light source devices and applications.

Aspects of the disclosure are directed to an apparatus for providing an ionic fluid antenna. The apparatus may include a body configured to contain an ionic fluid, an acoustic transducer coupled to the body, and a power supply coupled to the acoustic transducer that is configured to drive the acoustic transducer in accordance with at least one frequency. Aspects of the disclosure are directed to an apparatus for providing an ionic fluid antenna used in secure communications, comprising: a body configured to contain an ionic fluid, an acoustic transducer coupled to the body, and a power supply coupled to the acoustic transducer that is con figured to drive the acoustic transducer based on an encryption of data using polarized photons for quantum key distribution.

The present invention is directed at a waveguide antenna for microwave enhanced combustion of a previously ignited fuel-air mixture. The waveguide antenna has a thermal conductivity of at least 150 W/m-k and can be formed from a metallic shell with a ceramic core.

An aircraft communications system may include a RF-transparent enclosure, a plasma antenna element and a controller. The RF-transparent enclosure may be disposed substantially conformal with a portion of the aircraft. The plasma antenna element may be housed within the RF-transparent enclosure. The controller may be operably coupled to the plasma antenna element to provide control of operation of the plasma antenna element. The plasma antenna element may include one or more RF-conductive plasma devices that are selectively ionized to a plasma state under control of the controller.

A plasma antenna assembly may include a plasma antenna element, a plasma density sensor operably coupled to the plasma antenna element to measure plasma density during ionization of the plasma antenna element, a driver circuit operably coupled to the plasma antenna element to selectively provide pulsed current to the plasma antenna element for ionization of plasma in the plasma antenna element, and a controller operably coupled to the driver circuit and the plasma density sensor to provide control of the plasma density of the plasma antenna element.