Reflector (antenna)

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

Reflectarray antenna system

Abstract: One embodiment describes a reflectarray antenna system. The system includes an antenna feed configured to at least one of transmit and receive a wireless signal occupying a frequency band. The system also includes a reflector comprising a reflectarray. The reflectarray includes a plurality of reflectarray elements, where each of the reflectarray elements includes a dipole element. The dipole element of at least a portion of the plurality of reflectarray elements comprises a crossed-dipole portion and a looped-dipole portion. The plurality of reflectarray elements can be configured to selectively phase-delay the wireless signal to provide the wireless signal as a coherent beam.

Eyepiece for near-to-eye display with multi-reflectors

Abstract: An eyepiece for a head mounted display includes an illumination module, an end reflector, a viewing region, and a polarization rotator. The illumination module includes an image source for launching computer generated image ("CGI") light along a forward propagating path. The end reflector is disposed at an opposite end of the eyepiece from the illumination module to reflect the CGI back along a reverse propagation path. The viewing region is disposed between the illumination module and the end reflector. The viewing region includes a polarizing beam splitter ("PBS) and non-polarizing beam splitter ("non-PBS") disposed between the PBS and the end reflector. The viewing region redirects the CGI light from the reverse propagation path out of an eye-ward side of the eyepiece. The polarization rotator is disposed in the forward and reverse propagation paths of the CGI light between the viewing region and the end reflector.

Wireless antenna for emitting conical radiation

Abstract: An antenna described herein includes a driven patch that is configured to emit radiation in a broadside direction in response to receiving excitation current, wherein the driven patch has a first radiating edge and a second radiating edge that are approximately parallel to one another. The antenna also includes a reflector element that is configured to reflect radiation emitted from the first radiating edge in a quasi-endfire direction. The antenna can also include two director elements that are configured to direct radiation emitted from the second radiating edge of the driven patch in a quasi-endfire direction.

Vertical beaming of wavelength-scale photonic crystal resonators

Abstract: We report that $g80%$ of the photons generated inside a photonic crystal slab resonator can be funneled within a small divergence angle of $\ifmmode\pm\else\textpm\fi{}30\ifmmode^\circ\else\textdegree\fi{}$. The far-field radiation properties of a photonic crystal slab resonant mode are modified by tuning the cavity geometry and by placing a reflector below the cavity. The former method directly shapes the near-field distribution so as to achieve directional and linearly polarized far-field patterns. The latter modification takes advantage of the interference effect between the original waves and the reflected waves to enhance the energy directionality. We find that, regardless of the slab thickness, the optimum distance between the slab and the reflector closely equals one wavelength of the resonance under consideration. We have also discussed an efficient far-field simulation algorithm based on the finite-difference time-domain method and the near- to far-field transformation.

Pollutant Detection by Absorption Using Mie Scattering and Topographic Targets as Retroreflectors

Abstract: Remote pollutant measurement by absorption using topographical reflectors or atmospheric Mie scattering as a distributed reflector offers increased range and sensitivity compared to that achieved by Raman or resonance backscattering methods. The use of topographical reflectors offers the advantage of a single-ended absorption measurement for ranges up to 10 km and sensitivities to less than 0.01 ppm for a 10-mJ, 100-nsec transmitted pulse. The distributed Mie reflector permits absorption measurements over a depth cτ/2, determined by the pulse length τ, and allows ranging by time-of-flight measurement. For a 100-mJ, 100-nsec pulse sensitivities to 0.3 ppm at a 15-m depth resolution to ranges of 1–4 km are possible. This sensitivity is 104 to 105 times better than that achieved by the Raman method.