Results 171 to 180 of about 8,681 (211)

Fresnel zone plate antenna with hexagonal‐cut zones

Microwave and Optical Technology Letters, 2008
AbstractA 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, A. Petosa, I. V. Minin, O. V. Minin, J. S. Wight   +4 more
openaire   +1 more source

The elliptical Fresnel-zone plate antenna

Ninth International Conference on Antennas and Propagation (ICAP), 1995
The 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.
openaire   +3 more sources

Fresnel Zone-Plate Diffraction Patterns

Journal of the Optical Society of America, 1969
The diffraction patterns of the central aperture and the first 10 rings of the classical Fresnel zone plate are calculated in the principal focal plane for off-axis distances as large as the radius of the 10th ring. The zone-plate pattern is found by summation; near the axis it is compared with closed-form approximations.
openaire   +1 more source

Fresnel zone plate reflector incorporating rings

IEEE Microwave and Guided Wave Letters, 1993
A novel high-efficiency Fresnel zone plate reflector antenna is presented. The reflector consists of an inhomogeneous array of circular conducting rings printed on a grounded substrate. By adjusting the geometrical parameters of the rings and the distances between them, the reflector provides a space-varying phase correction required for focusing an ...
Y.J. Guo, S.K. Barton
openaire   +1 more source

Single zone Fresnel dielectric plate antenna

2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2019
It is shown that simple dielectric disk with proper chosen refractive index, radius and thickness operate as lens and can increase for more than 10 dB directivity of the antenna couple detectors placed at the focal plane.
A. Hakhoumian, A. Sargsyan
openaire   +1 more source

Fresnel Zone Plate and Fresnel Phase Plate Patterns for Acoustic Transducers

1984
An ultrasonic transducer with an electrode pattern in the shape of a Fresnel zone plate (FZP) is useful in acoustic imaging. However a major problem in focusing with an FZP is that the final image will have a large zero-order component and this will restrict the dynamic range of the system.
M. Mortezaie, G. Wade
openaire   +1 more source

Fresnel zone plates for two wavelengths

SPIE Proceedings, 1995
This paper proposes two systems of Fresnel Zone Plates which could focus two parallel monochromatic and coherent beams (with different wavelengths), eliminating the wellknown chromatical aberrations of the classical construction.
Eugene O. Curatu, Roxana N. Radvan, Roxana Savastru   +2 more
openaire   +1 more source

Comprehensive focusing analysis of various Fresnel zone plates

Journal of the Optical Society of America A, 2004
A series-form expression for the individual diffracted field of a general annular ring is derived from the Rayleigh-Sommerfeld diffraction integral. It can be used for the accurate and fast simulation of any diffractive focusing element composed of concentric transparent rings.
Qing, Cao, Jürgen, Jahns
openaire   +2 more sources

Fresnel Zone Plate array fabricated by maskless lithography

2015 30th Symposium on Microelectronics Technology and Devices (SBMicro), 2015
This work reports the fabrication of Fresnel Zone Plates (FZP) by employing a maskless lithography tool based on direct laser writing. The target application areas in this work are to use a micro lens array (MLA) in a wavefront sensor, for optical aberrations quantification in human eye diagnostics or adaptive optical system. This last one is essential
Barea, Luis A., Zuben, Antonio A., M-Brahim, Tayeb, Montagnoli, Arlindo N., Hospital, Michel, Frateschi, N., Cirino, Giuseppe A.   +6 more
openaire   +1 more source

Fresnel Zone Plate Imaging of Gamma Rays; Theory

Applied Optics, 1973
The use of a Fresnel zone plate as a coded aperture for imaging incoherent radiation such as gamma rays has been previously reported. The coded image is in many respects similar to a hologram and can be decoded or reconstructed with a coherent optical system.
H H, Barrett, F A, Horrigan
openaire   +2 more sources