A dual-mode polarizer for selectively switching between linear polarization and circular polarization includes a first meander-line polarizer, and a second meander-line polarizer spaced apart from the first meander-line polarizer to define a first gap therebetween. A first angular orientation between the first and second meander-line polarizers produces variably-oriented linear polarization of a signal passing through the first and second meander-line polarizers, and a second angular orientation between the first and second meander-line polarizers produces variably-oriented circular polarization of a signal passing through the first and second meander-line polarizers.

A leaky-wave antenna includes a substrate extending along an axis, and a dielectric waveguide extending along the axis and arranged in the substrate. The dielectric waveguide includes at least a top side, a bottom side, and opposite sides arranged between the top and bottom sides. A distance defined between the opposite sides varies along the axis for at least part of a length of the dielectric waveguide.

A leaky-wave antenna includes a substrate extending along an axis, and a dielectric waveguide extending along the axis and arranged in the substrate. The dielectric waveguide includes at least a top side, a bottom side, and opposite sides arranged between the top and bottom sides. A distance defined between the opposite sides varies along the axis for at least part of a length of the dielectric waveguide.

Provided is an antenna device including a feeding antenna conductor, a non-feeding antenna conductor, a ground conductor, and an artificial magnetic conductor disposed between the feeding antenna conductor and the non-feeding antenna conductor, and the ground conductor. The antenna device further includes a conductor that electrically connects the artificial magnetic conductor to the ground conductor. The conductor is disposed at a position opposite to the feeding antenna conductor with respect to the non-feeding antenna conductor, and is separated from the non-feeding antenna conductor.

Provided is an antenna device including a feeding antenna conductor, a non-feeding antenna conductor, a ground conductor, and an artificial magnetic conductor disposed between the feeding antenna conductor and the non-feeding antenna conductor, and the ground conductor. The antenna device further includes a conductor that electrically connects the artificial magnetic conductor to the ground conductor. The conductor is disposed at a position opposite to the feeding antenna conductor with respect to the non-feeding antenna conductor, and is separated from the non-feeding antenna conductor.

Polarization current antennas include an arc-shaped dielectric radiator, electrodes, and a feed network. The electrodes and feed network are configured to generate an electric field within the dielectric radiator. The electrodes are positioned on the top and bottom of the dielectric radiator and the electromagnetic radiation is emitted through the outer surface thereof. Phase differences between excitation signals supplied to the electrodes may be selected so that a speed of a volume polarization distribution current pattern that is generated in the dielectric radiator will be substantially equal to the speed of light within the dielectric radiator. The antenna emits both conventional spherically decaying electromagnetic radiation and as non-spherically decaying electromagnetic radiation that decays as a function of distance d at a rate that is less than 1/d.sup.2. The non-spherically decaying radiation includes a highly focused beam that has an angular beamwidth that narrows as the distance d increases.

An antenna is provided. The antenna includes a transparent substrate and a metal layer disposed on the transparent substrate. The metal layer includes a plurality of hollow regions, at least one hollow region in the plurality of hollow regions is surrounded by at least one metal line group and the at least one metal line group includes at least one metal line; a cross section of the at least one metal line has a non-rectangular shape.

A surface-wave waveguide may include a base conductive ground plane including opposite side edges and a pair of conductive side walls. One conductive side wall extends from each side edge of the conductive ground plane. The surface-wave waveguide may also include a substrate including a dielectric material disposed on the base conductive ground plane and between the conductive side walls. The surface-wave waveguide may also include an impedance sheet disposed on the substrate and between the conductive side walls. The impedance sheet may include a predetermined impedance characteristic for transmitting an electromagnetic wave.

A surface-wave waveguide may include a base conductive ground plane including opposite side edges and a pair of conductive side walls. One conductive side wall extends from each side edge of the conductive ground plane. The surface-wave waveguide may also include a substrate including a dielectric material disposed on the base conductive ground plane and between the conductive side walls. The surface-wave waveguide may also include an impedance sheet disposed on the substrate and between the conductive side walls. The impedance sheet may include a predetermined impedance characteristic for transmitting an electromagnetic wave.

An UC dielectric waveguide of the embodiments includes: a dielectric substance wiring propagating a terahertz wave; and a medium disposed around the dielectric substance wiring and having a large refractive index difference with respect to the dielectric substance wiring. A THz circuit of the embodiments includes a dielectric substance THz circuit connected between a first and second UC dielectric waveguides. The dielectric substance THz circuit includes a circuit including a linear-shaped UC dielectric waveguide, a bent-shaped UC dielectric waveguide, and a Y-coupled branch circuit. There are included a first holding unit holding the first UC dielectric waveguide and a second holding unit holding the second UC dielectric waveguide. The THz circuit of the embodiments may include a 2×2 evanescent coupler. Provided is a THz circuit having mechanical strength obtained by applying the UC dielectric waveguide having high confinement and transmission efficiencies of THz waves with a simple structure.