An antenna device includes a ground conductor (1), a dielectric tube (2) containing an ionizing gas and passing through the ground conductor, whose folded-back portion (201) and both ends are disposed in different sides of the ground conductor, first electrodes (3, 4) disposed at both ends of the dielectric tube (2), a plasma excitation power supply connected to the first electrodes, bringing the ionizing gas into a plasma state; a second electrode (6) ring-shaped and disposed at the both ends side of dielectric tube (2) from the ground conductor (1), fitted to and in contact with the dielectric tube outer surface, a high frequency transmitter (7) supplying a high frequency signal to the second electrode (6), and a feed line (8) connecting the second electrode and the high frequency transmitter. Each end of the dielectric tube (2) is larger than the second electrode in the inner diameter.

In an antenna including a dielectric window and a slot plate provided on one surface of the dielectric window, in a case where a reference position g is a center position in a width direction of each slot S and a center position in a length direction in the slot plate, the reference position g of each slot is located on a virtual circle centered on a center of gravity G0, and line segments connecting the reference positions g of the slots S and virtual point G1 to which the slots belong are located radially from a virtual point G1, angles (1 to 4) between adjacent line segments are equal to each other, and angles (1 to 4) formed by the length directions of the slots S at the reference positions g and the line segments to which the slots belong are equal to each other.

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).

Provided is a semiconductor plasma antenna apparatus. The apparatus includes: a cell array unit in which a plurality of PIN diode cells are arranged, and in which a cell pattern is formed by using a predefined PIN diode cell among the plurality of PIN diode cells; and a driver circuit unit configured to control a drive of the predefined PIN diode cell, wherein the driver circuit unit comprises: a direct-current conversion unit equipped with a DC-DC converter configured to drive a diode load of the cell pattern by applying an output voltage to a PIN diode cell corresponding to the cell patterns formed in the cell array unit; and a constant current controller configured to controlling a plasma concentration of the PIN diode cell by controlling a constant current for the diode load of the cell pattern.

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.

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.

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.

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.

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.

Provided is a semiconductor plasma antenna apparatus. The apparatus includes: a cell array unit in which a plurality of PIN diode cells are arranged, and in which a cell pattern is formed by using a predefined PIN diode cell among the plurality of PIN diode cells; and a driver circuit unit configured to control a drive of the predefined PIN diode cell, wherein the driver circuit unit comprises: a direct-current conversion unit equipped with a DC-DC converter configured to drive a diode load of the cell pattern by applying an output voltage to a PIN diode cell corresponding to the cell patterns formed in the cell array unit; and a constant current controller configured to controlling a plasma concentration of the PIN diode cell by controlling a constant current for the diode load of the cell pattern.