Results 171 to 180 of about 27,387 (213)
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Offset Fresnel zone plate antennas
International Journal of Satellite Communications, 1994AbstractThe theory of offset Fresnel zone plate antennas is presented. Explicit formulae for the design of the zone boundaries for the offset Fresnel zone plate are given. Theorectical equations and numerical results for the far‐field analysis are presented.
Y. J. Guo, S. K. Barton
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The Interferometric Fresnel Zone
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010We present a way to implement the virtual source (VS) method in a real scenario where a summation over all the available sources in the dataset may not be the optimal solution. Because the main contributions to the interferometric data construction come from sources at stationary locations, a target-oriented source selection could reduce artefacts ...
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A cylindrical Fresnel zone antenna
IEEE Transactions on Antennas and Propagation, 1996A cylindrical Fresnel zone antenna as a candidate for a base station in wireless indoor LAN systems is described. An arbitrary angle-tilted fan beam in azimuth can be achieved by moving the position of the strip dipole feed at the cylinder center.
Y. Ji, M. Fujita
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Defining the Fresnel zone for broadband radiation
Physical Review E, 2002The concept of the Fresnel zone is central to many areas of imaging. In tomographic imaging, the transverse spatial resolution can be limited by the size of the first Fresnel zone, usually defined only for monochromatic radiation. With the increasing prevalence of broadband tomographic imaging systems, a generalization of this concept is required. Here,
Jeremy, Pearce, Daniel, Mittleman
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The Bandwidth of Fresnel-Zone Plate Antennas
Journal of Electromagnetic Waves and Applications, 1997Theoretical expressions are presented for the illumination and phase efficiency of three types of Fresnel-zone plate antennas. Using these formulas, the bandwidths of the antennas will be analyzed and compared. Measured data are given to validate the theoretical results.
van Houten, J.M., Herben, M.H.A.J.
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Fresnel Zone Wavepath Tomography - Theory
The 3rd International Symposium on Recent Advances in Exploration Geophysics (RAEG 1998), 1998In this paper, a developing wavepath based on diffraction tomography in the space-time domain is presented. This wavepath is named Fresnel zone wavepath, derived from the imaginary part of Rhytov approximation. This wavepath is calculated using travel times from source to any point, receiver to any point and source to receiver.
B.E.B. Nurhandoko, Y. Ashida
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Image reconstruction from partial Fresnel zone information
Applied Optics, 1985An iterative algorithm for reconstructing an image from partial Fresnel zone information is discussed. With the standard 4-F canonical optical processor, processing is done midway between the two lenses in the Fourier transform plane. While others have studied reconstruction from partial Fourier plane information, we have investigated methods of ...
R, Rolleston, N, George
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SPIE Proceedings, 1985
A description is given of the use of the Fresnel zone plate as a focusing or a frequency-filtering device at millimeter wavelengths. Sample design data are given, as well as references to prior results. A newer type of zone plate is discussed which employs two dielectrics of equal thickness to produce a flat zone plate.
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A description is given of the use of the Fresnel zone plate as a focusing or a frequency-filtering device at millimeter wavelengths. Sample design data are given, as well as references to prior results. A newer type of zone plate is discussed which employs two dielectrics of equal thickness to produce a flat zone plate.
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Fresnel zone plate: Anomalous foci
American Journal of Physics, 1976It is found that, when a zone plate is examined in practice, foci exist where there should be none. An approach is developed which reveals that the zone plate is a circular diffraction grating, which in turn explains how a hologram works in a very direct manner.
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Nomogram for Fresnel‐zone calculation
GEOPHYSICS, 1980Geophysicists commonly recognize that a sizeable portion of a reflector is involved in causing a reflection as seen on a seismic trace, but the areal extent is usually not calculated and hence not appreciated. Most commonly, concepts are simply transferred from classical physical optics and called Fresnel‐zone effects.
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