The disclosed structures and methods are directed to antenna systems configured to transmit and receive a wireless signal in and from different directions. A switchable lens antenna has excitation ports radiating radio-frequency (RF) wave into a parallel-plate waveguide structure, and a frequency selective structure (FSS). The antenna presented herein is configured to operate in two modes depending on a steering angle of the RF wave propagating in the parallel-plate waveguide structure. When the steering angle is about or less than a threshold steering angle, FSS is OFF due to its stubs being electrically disconnected from the parallel-plate waveguide structure. When the steering angle is higher than the threshold, FSS is ON with stubs being electrically connected to the parallel-plate waveguide structure. When ON, FSS provides phase variance to the RF wave propagating in the parallel-plate waveguide structure and increases steering angle of the RF wave.

The disclosed structures and methods are directed to antenna systems configured to transmit and receive a wireless signal in and from different directions. A switchable lens antenna has excitation ports radiating radio-frequency (RF) wave into a parallel-plate waveguide structure, and a frequency selective structure (FSS). The antenna presented herein is configured to operate in two modes depending on a steering angle of the RF wave propagating in the parallel-plate waveguide structure. When the steering angle is about or less than a threshold steering angle, FSS is OFF due to its stubs being electrically disconnected from the parallel-plate waveguide structure. When the steering angle is higher than the threshold, FSS is ON with stubs being electrically connected to the parallel-plate waveguide structure. When ON, FSS provides phase variance to the RF wave propagating in the parallel-plate waveguide structure and increases steering angle of the RF wave.

A wave plate comprising: a prism member having an entrance surface for receiving a terahertz wave T, and an exit surface for emitting the terahertz wave T received by the entrance surface; wherein the prism member is constituted by a plurality of waveguide regions having: a partial entrance surface for receiving a part of the terahertz wave T, a plurality of total reflection surfaces for totally reflecting the terahertz wave T from the partial entrance surface, and a partial exit surface for emitting the terahertz wave T totally reflected from the total reflection surfaces; and each of the partial entrance surfaces combine to constitute the entrance surface of the prism member, and each of the partial exit surfaces combine to constitute the exit surface of the prism member, by stacking waveguide regions.

A wave plate comprising: a prism member having an entrance surface for receiving a terahertz wave T, and an exit surface for emitting the terahertz wave T received by the entrance surface; wherein the prism member is constituted by a plurality of waveguide regions having: a partial entrance surface for receiving a part of the terahertz wave T, a plurality of total reflection surfaces for totally reflecting the terahertz wave T from the partial entrance surface, and a partial exit surface for emitting the terahertz wave T totally reflected from the total reflection surfaces; and each of the partial entrance surfaces combine to constitute the entrance surface of the prism member, and each of the partial exit surfaces combine to constitute the exit surface of the prism member, by stacking waveguide regions.

Antenna arrays with three-dimensional (3D) conformal radiating elements are provided, as well as methods of manufacturing and methods of using the same. An array can include a ground plane and a plurality of unit cells disposed thereon. Each unit cell can include a 3D conformal radiating element. The 3D conformal radiating elements can be, for example, patches (e.g., circular 3D patches), dipoles, or loops, and each radiating element is conformal on a hemispherical shape.

Antenna arrays with three-dimensional (3D) conformal radiating elements are provided, as well as methods of manufacturing and methods of using the same. An array can include a ground plane and a plurality of unit cells disposed thereon. Each unit cell can include a 3D conformal radiating element. The 3D conformal radiating elements can be, for example, patches (e.g., circular 3D patches), dipoles, or loops, and each radiating element is conformal on a hemispherical shape.

A sheet-type metamaterial includes: a film-shaped dielectric substrate; a first and second wire array formed on the dielectric substrate's front surface and back surface respectively. The first wire array includes elongated metallic first cut wires of a length aligned in a y-axis direction with a gap g therebetween and in an x-axis direction with space s therebetween. The second wire array includes second cut wires having the same shape as first cut wires and aligned so as to overlap first cut wires and to be symmetric with the first cut wires. With a design frequency set at 0.51 THz, the dielectric substrate's thickness d is set at about 50 m, space s is set at about 361 m, gap g is set at about 106 m, and the length of first and second cut wires is set at a length approximate to a value to generate resonance at a working frequency.

Various examples are provided related to hybrid multiple-input/multiple-output (MIMO) architectures. Beam steering can be provided using lens arrays. In one example, a hybrid antenna system includes a plurality of lens antenna subarrays (LAS), each of the LAS including a plurality of antenna elements configured to selectively receive a radio frequency (RF) transmission signal from RF processing circuitry, and a lens extending across the plurality of antenna elements. The RF transmission signal can be provided to a selected antenna of the plurality of antenna elements via a switching network and a common phase shifter for transmission. The lens can be configured to steer a RF transmission generated by the selected antenna in a defined direction. The selected antenna can be determined by the switching network configuration.

Various examples are provided related to hybrid multiple-input/multiple-output (MIMO) architectures. Beam steering can be provided using lens arrays. In one example, a hybrid antenna system includes a plurality of lens antenna subarrays (LAS), each of the LAS including a plurality of antenna elements configured to selectively receive a radio frequency (RF) transmission signal from RF processing circuitry, and a lens extending across the plurality of antenna elements. The RF transmission signal can be provided to a selected antenna of the plurality of antenna elements via a switching network and a common phase shifter for transmission. The lens can be configured to steer a RF transmission generated by the selected antenna in a defined direction. The selected antenna can be determined by the switching network configuration.

An ultra-wideband linear-to-circular polarizer is disclosed. In accordance with embodiments of the invention, the polarizer includes a plurality of cascaded waveplates having biaxial permittivity or cascaded anisotropic sheet impedances. Each waveplate/sheet has a principal axis rotated at different angles relative to an adjacent waveplate/sheet about a z-axis of a 3-dimensional x, y, z coordinate system. Each waveplate is composed of a unit cell of an artificial anisotropic dielectric. Each sheet impedance is composed of an anisotropic metallic pattern. The polarizer further includes impedance matching layers disposed adjacent the cascaded waveplates/sheets.