Results 191 to 200 of about 99,715 (244)
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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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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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Quantum Noise in Fresnel Zone Plate Imaging
Applied Optics, 1974A Fresnel zone plate, used as a coded aperture, offers a great advantage in geometric collection efficiency over a conventional pinhole or collimator. We present a detailed analysis of the signal-to-noise ratio (SNR) of a quantum-limited zone plate camera.
H H, Barrett, G D, Demeester
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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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Optimization of polygonal Fresnel zone plates
Microwave and Optical Technology Letters, 2007AbstractThe performance of Fresnel zone plates having polygonal boundaries between zones has been studied for polygons with a low number of sides. An optimized polygonal shape has been analytically defined by minimizing the mismatched area between the circular and the polygonal pseudo‐Fresnel zones.
Alda, Javier, Boreman, Glenn
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Focalization of Fresnel-Cantor zone plates
SPIE Proceedings, 2003We extend the results obtained for different cases of the product superposition between periodic functions to the case of circular symmetry. The characteristics of focalization for such case is studied. We name Fresnel-Cantor zone plate to the structures obtained.
Diana E. Calva Mendez, Mario M. Lehman
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Multilayer offset Fresnel zone plate reflector
IEEE Microwave and Guided Wave Letters, 1994An offset phase-correcting Fresnel zone plate (FZP) reflector antenna based on the multilayer configuration is presented. The reflector consists of a conducting ground and four layers of conducting patterns separated by four dielectric substrates. An experimental prototype designed at 10.39 GHz was fabricated and tested.
Y.J. Guo, I.H. Sassi, S.K. Barton
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A Millimeter-Wave Fresnel Zone Plate Lens Design Using Perforated 3D Printing Material
IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications, 2018This paper presents a novel Fresnel Zone Plate Lens (FZPL) using perforated 3D printing material at 60 GHz$\lambda_\mathrm {0} = \mathrm {5.45 mm}$. A gradient refractive index condition is controlled using the air-hole approach in the dielectric slab ...
J. Pourahmadazar +3 more
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Fresnel zone plate antenna with hexagonal‐cut zones
Microwave and Optical Technology Letters, 2008AbstractA novel Fresnel zone plate antenna (FZPA) with hexagonal‐cut zones is presented. This new structure was simulated at 30 GHz using a finite‐difference time‐domain software to study its gain and sidelobe levels in relation to the standard circular FZPA and the hexagonal FZPA. Several prototypes were built and tested to verify the simulations.
S. M. Stout‐Grandy +4 more
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The elliptical Fresnel-zone plate antenna
Ninth International Conference on Antennas and Propagation (ICAP), 1995The growing number of direct broadcast satellites (DBS) asks for simple, low-cost home receiving systems. The use of the Fresnel-zone plate antenna (FZPA), which is related to the optical lens, is also promising for this application. The aperture of the FZPA is plane and its structure is determined by the well-known Fresnel ellipsoids.
van Houten, J.M., Herben, M.H.A.J.
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