Topic
Reflector (antenna)
About: Reflector (antenna) is a research topic. Over the lifetime, 28730 publications have been published within this topic receiving 212618 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a beam steering mechanism for a modular mesh-type deployable antenna is described, which yields a beam pointing accuracy of better than 0.1°, and the influence of modular connection errors on surface accuracy is quantitatively estimated.
123 citations
TL;DR: An optimal beamforming strategy is proposed for performing large-field surveys with dual-polarized phased-array-fed reflector antennas and the obtained numerical results demonstrate a very good agreement with the measurements performed at the telescope.
Abstract: An optimal beamforming strategy is proposed for performing large-field surveys with dual-polarized phased-array-fed reflector antennas. This strategy uses signal-processing algorithms that maximize the beam sensitivity and the continuity of a field of view (FOV) that is formed by multiple closely overlapping beams. A mathematical framework and a newly developed numerical approach are described to analyze and optimize a phased array feed (PAF) system. The modeling approach has been applied to an experimental PAF system (APERTIF prototype) that is installed on the Westerbork Synthesis Radio Telescope. The resulting beam shapes, sensitivity, and polarization diversity characteristics (such as the beam orthogonality and the intrinsic cross-polarization ratio) are examined over a large FOV and frequency bandwidth. We consider weighting schemes to achieve a conjugate-field matched situation (max. received power), maximum signal-to-noise ratio (SNR), and a reduced SNR scenario but with constraints on the beam shape. The latter improves the rotational symmetry of the beam and reduces the sensitivity ripple, at a modest maximum sensitivity penalty. The obtained numerical results demonstrate a very good agreement with the measurements performed at the telescope.
122 citations
TL;DR: In this article, the authors describe two alternative designs with fewer layers for the application as coherent emission sources in planar multilayer structures, which can be obtained by the excitation of surface waves between the photonic crystal and the reflector.
Abstract: A large number of recent publications dealt with enhanced emission properties of micro/nanostructures by the excitation of surface plasmon or phonon polaritons. Some used grating structures to demonstrate coherent thermal emission in a narrow spectral band and towards a well-defined direction. Others suggested that planar layers could also be used to achieve coherent emission. In the present paper, we describe two alternative designs with fewer layers for the application as coherent emission sources in planar multilayer structures. One design is a composite of several unit cells of one-dimensional photonic crystal atop a highly reflective material. Coherent emission can be obtained by the excitation of surface waves between the photonic crystal and the reflector. The other design employs a Fabry-Perot resonance cavity constructed by coating a dielectric layer onto the reflector and then a thin metallic film on the dielectric layer. When standing waves exist in the cavity, the emissivity plots show sharp s...
121 citations
Patent•
05 Mar 2014
TL;DR: In this paper, an imaging antenna system with compensated optical aberrations consisting of a main a paraboloid reflector (4), a first sub-reflector (6), and a first feeding array (8) is described.
Abstract: An offfset imaging antenna system with compensated optical aberrations comprises a main a paraboloid reflector (4), a first paraboloid sub reflector (6), and a first feeding array (8) as an arrangement of first feed array elements to illuminate or to be illuminated by the first sub reflector. The main reflector (4) and the first sub reflector (6) are confocal by sharing a common focal point. The first feeding array (8) has a curved shape that corresponds to a first equivalent array (12) of magnified image feed elements (14) lying on a plane (16) crossing the main optical centre and perpendicular to the main bore-sight axis, all the first feed array elements (10) being positioned as to provide a planar distribution of the positions of the image feed elements (14) onto the first equivalent array (12) after a second reflection by the main reflector (4) with a central image point coinciding with the main reflector optical centre under a maximum illumination condition.
121 citations
TL;DR: The concept of the reflective solar tower is based on inverting the path of the solar rays originating from a heliostat field to a solar receiver that can be placed on the ground as mentioned in this paper.
120 citations