An electromagnetic wave transmission structure adapted to cause convergence of an electromagnetic wave includes a substrate and a transmission unit provided on the substrate and including an annular metal plate. The annular metal plate has a weighted average inner radius and a weighted average outer radius each related to the wavelength of the electromagnetic wave, the distance between the electromagnetic wave transmission structure and a focal point defined as the point of convergence of the electromagnetic wave, and the distance between the source of the electromagnetic wave and the focal point. The plural inner and outer radii of the annular metal plate have the same trend of variation. Each inner or outer radius corresponds to a weight related to the reference included angle formed between the inner or outer radius and a reference axis.

Various examples are provided for flat lens antennas and their operation. In one example, among others, an antenna includes electrically thin (W<<λhigh), highly conducting, TEM mode antenna arms fed at a first end by a balun. The TEM mode antenna arms can be embedded in a spatially varied anisotropic dielectric material. A separation between the TEM mode antenna arms can increase from the first end to a second end where the TEM mode antenna arms transition to resistive card (Rcard) terminations when the TEM mode antenna arms are separated by a distance Hr, where a ratio of Hr to a height (H) of the antenna is in a range from about 0.2 to about 0.8.

An apparatus includes a lens with substantially flat first surface and a substantially tiered second surface opposite the substantially flat first surface, where the substantially tiered second surface has at least a central tier and a second tier, the central tier and the second tier each having a different thickness from the other tier, and where the thickness of each tier as measured orthogonally from the substantially flat first surface is chosen to provide a delay for the signal passing through the lens to approximate the characteristics of a Luneburg type lens as a radar beam is swept across the substantially first surface.

An antenna unit including an antenna array having a plurality of antennas and a lens plate comprising a mask pattern. The antenna array defines a first plane, and the lens plate defines a second plane. The lens plate is spaced apart from the antenna array, and the second plane is parallel to the first plane. The mask pattern is configured to focus first waves incident on the lens plate through diffraction to a region of the antenna array. The first waves are incident on the lens plate at a first angle relative to an axis normal to the second plane. The mask pattern is configured to focus second waves incident on the lens plate through diffraction to the first region of the antenna array. The second waves are incident on the lens plate at a second angle relative to the axis that is different from the first angle.

A folded lens antenna structure comprising: a stack comprising in order: a reflector; a dielectric gap; and a sub-reflector plate of smaller area than the reflector.

The present disclosure provides a lens assembly, a terahertz wave tomography system and method, and a terahertz wave filter. The lens assembly includes: a first substrate and a second substrate that are oppositely disposed; a seal, wherein the seal, the first substrate and the second substrate enclose a cavity in which a magnetic fluid is filled; and a plurality of electromagnetic generating units disposed on at least one of a first side of the first substrate close to the second substrate or a second side of the first substrate away from the second substrate, wherein at least a part of the plurality of electromagnetic generating units are configured to generate a magnetic field in a case where a voltage is applied to make the magnetic fluid form a Fresnel zone plate pattern.

A terahertz wave lens includes a substrate having a surface provided with an uneven structure that changes a phase of the terahertz wave. The uneven structure includes a plurality of holes that are periodically arranged. The uneven structure includes a plurality of regions where the plurality of holes are arranged. A height of the hole in a thickness direction of the substrate and a width of the pillar differ for each of the regions. Outer end portions of the uneven structure in the thickness direction are located on the same plane.

An object of the present invention is to provide a method for designing a gradient index lens enabling to easily and accurately drive an antenna. According to the present invention, a virtual domain a boundary of which includes a curved focal plane in a uniform-refractive-index type lens with a uniform refractive index, and a physical domain a boundary of which includes a planar focal plane in a gradient index lens with a non-uniform refractive index and that is a quasiconformal map of the virtual domain are set, the quasiconformal map of a virtual medium parameter that is a medium parameter including at least one of a dielectric constant and magnetic permeability characterizing the virtual domain is calculated as a physical medium parameter in the physical domain, and the gradient index lens based on the physical medium parameter is designed by spatially arranging a medium parameter adjustment element set in advance.

The present invention relates to: a communication technique for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system; and a system therefor. The present invention provides an antenna module comprising: an antenna array for radiating beams through a top surface thereof, a dielectric disposed to be spaced apart from the top surface of the antenna array by a first preset length; a first reflector comprising a metallic material, and disposed to be spaced apart from the bottom surface of the dielectric by a second preset length; and a second reflector comprising a metallic material and disposed in the partial region of the bottom surface, of the dielectric, which faces the top surface of the antenna array.

A millimeter-wave optical imaging system including an imaging detector located at a focal plane of the optical imaging system, the imaging detector being responsive to electromagnetic radiation in wavelength range of approximately 5-50 millimeters, an immersion lens directly coupled to the imaging detector and configured to focus the electromagnetic radiation onto the imaging detector, wherein the focal plane is located on a planar surface of the immersion lens and the imaging detector is directly coupled to the planar surface, a positive power primary mirror configured to reflect the electromagnetic radiation towards the immersion lens, and one of a Fresnel lens or a diffraction grating configured to receive and direct the electromagnetic radiation towards the primary mirror.