Reflector (antenna)

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

Array feed synthesis for correction of reflector distortion and vernier beamsteering

Abstract: An algorithmic procedure is described for the synthesis of a planar-array for paraboloidal reflectors to provide simultaneously electronic correction of systematic reflector surface distortions as well as a vernier electronic beamsteering capability. Several f/D ratios and distortion models were examined that are typical of large paraboloidal reflectors. Numerical results are presented showing that, for the range of distortion models considered, significant on-axis gain restoration can be achieved with a one-ring (seven-element) array. However, with seven elements, the array parameters that maximize system gain, do not provide uniform beam-steering (+or-1 BW) and an additional ring (19 elements) is required. For arrays either 7 or 19 elements, the results indicate that the use of high-aperture-efficiency elements in the array yields higher system gain than can be obtained with elements having lower aperture efficiency. Contour plots of the focal-plane fields are also presented for various distortion and beam-scan-angle cases, showing the dynamic nature of the problem. >

Wideband Beam-Steerable Flat Reflectors via Transformation Optics

Abstract: A conventional parabolic reflector is converted into a flat one based on the discrete coordinate transformation. Instead of general beam-steering techniques, such as off-axis feeding, tilting the feed/reflector, or utilizing phase shift, we show an alternative way to manipulate the reflected emission through tuning transformed dielectrics. The proposed design, only including the conventional dielectric components, has a merit of keeping the flat profile of a compact reflector system while possessing the ability to steer the radiation beams in a wide frequency band.

Nitride-Based LEDs With a Hybrid Al Mirror $+ {\hbox {TiO}} _{2} /{\hbox {SiO}}_{2}$ DBR Backside Reflector

Abstract: Nitride-based light-emitting diodes (LEDs) with a hybrid backside reflector combining a TiO2/SiO2 distributed Bragg reflector (DBR) and an Al mirror were proposed and realized. It was found that we can significantly enhance the 35% reflectivity of the 2-pair TiO2/SiO2 DBR to 94% by combining with Al mirror (hybrid reflector). Furthermore, reflectivity of the proposed reflector depends only slightly on incident light wavelength and the incident angle. With 350-mA current injection, it was found that the output powers were 145.7, 178.2, and 201.9 mW for the LEDs with 2-pair DBR, with an Al mirror and with a hybrid reflector, respectively, when packaged in TO-cups. It was also found that reliability for the LED with the hybrid reflector is good.

Fast radiation pattern evaluation for lens and reflector antennas

Abstract: A novel algorithm referred to as the fast physical optics (FPO) for computing the radiation patterns of nonplanar aperture antennas over a range of observation angles is presented. The computation is performed in the framework of the conventional physical optics approximation appropriate for the high frequency regime. The proposed algorithm is directly applicable to reflector and lens antennas as well as to radomes. The method comprises two steps. First, a decomposition of the aperture into subdomains and computation of the pertinent radiation pattern of each subdomain. Second, interpolation, phase-correction and aggregation of the radiation patterns into the final pattern of the whole aperture. A multilevel algorithm is formulated via a recursive application of the domain decomposition and aggregation steps. The computational structure of the multilevel algorithm resembles that of the FFT while avoiding its limitations.

Semiconductor device inspection apparatus using a plurality of reflective elements

Abstract: An improved optical inspection apparatus, especially suited for inspecting semiconductor devices using a single camera. A highly polished mirrored stage is provided with a light source extending upwardly therethrough and providing a pedestal upon which the object to be inspected is centered. A plurality of stationary reflectors are disposed around the stage and function in concert with two separate movable reflectors to provide optical scanning over the appropriate surface portions of the device. A separate movable reflector system is used to maintain a constant focal path length between the device and the camera as the other movable reflectors scan the device, thus ensuring proper focus and measurement accuracy.