Reflector (antenna)

About: Reflector (antenna) is a research topic. Over the lifetime, 28730 publications have been published within this topic receiving 212618 citations.

Electronically step-by-step rotated directive radiation beam antenna

Abstract: This invention relates to an electronically rotatable antenna which includes several radially arranged Yagi antennae having a common drive element. Reflector and director elements of each Yagi antenna are sequentially rendered operative by biasing suitable diodes short-circuiting them to a ground-plate. The radiation pattern is step-by-step rotated. Directivity is increased by short-circuiting other elements belonging to other arrays than the main one, those elements defining generatrices of a parabola having the driver element as a focus and the reflector element as an apex.

Antenna Designs for CubeSats: A Review

Abstract: Cube Satellites, aka CubeSats, are a class of nano satellites that have gained popularity recently, especially for those that consider CubeSats as an emerging alternative to conventional satellites for space programs. This is because they are cost-effective, and they can be built using commercial off-the-shelf components. Moreover, CubeSats can communicate with each other in space and ground stations to carry out many functions such as remote sensing (e.g., land imaging, education), space research, wide area measurements and deep space communications. Consequently, communications between CubeSats and ground stations is critical. Any antenna design for a CubeSat needs to meet size and weight restrictions while yielding good antenna radiation performance. To date, a limited number of works have surveyed, compared and categorised the proposed antenna designs for CubeSats based on their operating frequency bands. To this end, this paper contributes to the literature by focusing on different antenna types with different operating frequency bands that are proposed for CubeSat applications. This paper reviews 48 antenna designs, which include 18 patch antennas, 5 slot antennas, 4 dipole and monopole antennas, 3 reflector antennas, 3 reflectarray antennas, 5 helical antennas, 2 metasurface antennas and 3 millimeter and sub-millimeter wave antennas. The current CubeSat antenna design challenges and design techniques to address these challenges are discussed. In addition, we classify these antennas according to their operating frequency bands, e.g., VHF, UHF, L, S, C, X, Ku, K/Ka, W and mm/sub-mm wave bands and provide an extensive qualitative comparison in terms of their size, −10 dB bandwidths, gains, reflection coefficients, and deployability. The suitability of different antenna types for different applications as well as the future trends for CubeSat antennas are also presented.

Reflector, reflective liquid crystal display incorporating the same and method for fabricating the same

Abstract: A reflector including a substrate and a thin metal film is provided. The substrate defines a plurality of randomly arranged, curved, surface deformity portions, each having an asymmetric cross section. Typically, the surface deformity/substrate structure is formed by creating curved pieces of resist material on a substrate, and thereafter, tilting and heating the substrate. Alternatively, a photoresist process utilizing an ion, or an electron beam without heating, can be used. The metal film is coated onto the surface of the substrate and onto the curved, surface deformities located thereon, such that light incident from a given direction is reflected over a wide range, but most intensely in particular directions. Further, a liquid crystal display is provided in which the reflector just mentioned is used as a lower substrate. An upper glass substrate is provided, and a liquid crystal display medium is interposed between the reflector and the upper glass substrate. In some embodiments, the liquid crystal display medium includes a matrix of polymer walls formed either by light irradiation using a mask, or by cooling a mixture of liquid crystal material, and a polymerizable precursor to separate phases prior to light irradiation. In addition, a phase plate, a polarizer, an insulating layer, display electrodes and/or color filters may be utilized in association with the liquid crystal display. Also, the liquid crystal material, the surface of the reflector substrate, and/or the thin metallic film may be divided into areas corresponding to individual pixels.

Compact optical structure with integrated source

Abstract: The invention relates to a compact optical structure comprising a semiconductor emitter junction, a laser or a light emitting diode, coupled to a plane waveguide formed by a layer of photo-polymer deposited on a substrate with a suitable index. A surface layer, of photo-polymer for example, enables the registration of photo-induced diffraction structures performing particular optical functions such as that of a distributed reflector, deflector or lens. Such compact structures are applicable, in particular to the designing of simple, small devices, laser sources with distributed external resonators, interferometric gyrometers, hydrophones, multiplexers or demultiplexers.

Angled distributed reflector optical device with enhanced light confinement

Abstract: A optical medium, such as an angled distributed reflector, e.g., an angular grating, or α-DFB laser diode or a waveguide wavelength selective filter, has a mean optical axis defining an optical cavity for substantially confined light propagation within the device. An angular grating is provided in at least a portion of the optical cavity forming a grating region permitting light to propagate along the optical cavity in two coupled waves or modes incident along the angular grating, a first incident propagating wave substantially parallel with respect to the mean optical axis and a second incident propagating wave at an angle with respect to the mean optical axis. At least one preferential coupling region in the optical cavity at an interface or boundary with the grating region to receive both propagating waves and provide for preferential treatment to the first incident propagating wave by coupling propagating light in the second incident propagating wave into the first incident propagating wave prior to light output from the medium via the non-grating region, forming a boundary with the grating region. The angle of the boundary at the interface of these respective regions is chosen to be substantially collinear with a propagation direction of the second incident propagating wave so that propagating light in the second incident propagating wave will substantially enter the preferential coupling region from the grating region via the boundary in a propagation direction substantially parallel with the mean optical axis.