Topic
Reflector (antenna)
About: Reflector (antenna) is a research topic. Over the lifetime, 28730 publications have been published within this topic receiving 212618 citations.
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TL;DR: In this article, the authors presented a theoretical analysis of a tilted wick solar still with a flat plate bottom reflector extending from the lower edge of the still on four days (the spring and autumn equinox and summer and winter solstices) at 30°N latitude when the still's inclination is fixed at 30.
79 citations
TL;DR: In this article, a fast ground-penetrating radar measurement technique using a multiple transmitter-and-receiver setup to measure simultaneously the reflector depth and average soil-water content is presented.
Abstract: Ground-penetrating radar is a fast noninvasive technique that can monitor subsurface structure and water-content distribution. To interpret traveltime information from single common-offset measurements, additional assumptions, such as constant permittivity, usually are required. We present a fast ground-penetrating-radar measurement technique using a multiple transmitter-and-receiver setup to measure simultaneously the reflector depth and average soil-water content. It can be considered a moving minicommon-midpoint measurement. For a simple analysis, we use a straightforward evaluation procedure that includes two traveltimes to the same reflector, obtained from different antenna separations. For a more accurate approach, an inverse evaluation procedure is added, using traveltimes obtained from all antenna separations at one position and its neighboring measurement locations. The evaluation of a synthetic data set with a lateral variability in reflector depth and an experimental example with a large variability in soil-water content are introduced to demonstrate the applicability for field-scale measurements. The crucial point for this application is the access to absolute traveltimes, which are difficult to determine accurately from common-offset measurements.
79 citations
TL;DR: In this paper, simplified design and analysis equations for multiple-beam reflector antennas based on the Gaussian-beam analysis of the primary and secondary patterns are presented for the quick design and performance analysis in terms of the coverage-area directivity and the inter-beam isolation of multiplebeam antenna systems.
Abstract: Simplified design and analysis equations are presented for multiple-beam reflector antennas based on the Gaussian-beam analysis of the primary and secondary patterns. The derived equations are useful for the quick design and performance analysis in terms of the coverage-area directivity and the inter-beam isolation of multiple-beam antenna systems. Results of the analysis given in this paper agree well with rigorous computations based on physical-optics analysis of the reflector-antenna radiation patterns. Extension of the analysis to multiple-beam lens antennas, and to shaped/contoured-beam antennas, is also presented.
79 citations
Patent•
04 Apr 1999
TL;DR: An optical component in the form of an identification element (such as for counterfeit protection or copy protection) includes an optically anisotropic layer comprising regions of different optical axes that is arranged over a reflector as discussed by the authors.
Abstract: An optical component in the form of an identification element (such as for counterfeit protection or copy protection) includes an optically anisotropic layer comprising regions of different optical axes that is arranged over a reflector The anisotropic layer may be implemented with a liquid crystal polymer in which the orientation of the liquid crystals is different in different areas Such an orientation pattern is initially hidden from a viewer, but becomes visible by means of an additional polariser To improve the visual appearance of the identification element, a white light hologram may be used for the reflector
78 citations
TL;DR: In this paper, the origin of a strong continuous radar reflector observed with airborne radio-echo sounding (RES) at the EPICA deep-drilling site in Dronning Maud Land, Antarctica, is identified as a transition in crystal fabric orientation from a vertical girdle to an increased single-pole orientation seen along the ice core.
Abstract: . The origin of a strong continuous radar reflector observed with airborne radio-echo sounding (RES) at the EPICA deep-drilling site in Dronning Maud Land, Antarctica, is identified as a transition in crystal fabric orientation from a vertical girdle to an increased single-pole orientation seen along the ice core. The reflector is observed with a 60 ns and 600 ns long pulse at a frequency of 150 MHz, spans one pulse length, is continuous over 5 km, and occurs at a depth of about 2025–2045 m at the drill site. Changes in conductivity as reflector origin are excluded by investigating the ice-core profile, synthetic RES data, and a RES profile with different electromagnetic polarisation azimuths. The reflector's magnitude shows maximum values for polarisation parallel to the nearby ice divide and disappears for polarisation perpendicular to it, identifying the orientation of the girdle to lie in the vertical plane parallel to the ice divide. Observations allow us to extrapolate the crystal orientation feature along the reflector in space, with implications for ice-sheet dynamics and modeling.
78 citations