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Author: J. F. McIlvenna Publisher: ISBN: Category : Aerial photography Languages : en Pages : 66
Book Description
The mapping of extended, cultural ground targets by an airborne radar is examined using communication theory concepts including those of the antenna transfer function and the target spatial frequency spectrum. Use of the set of transfer functions that correspond to Taylor aperture distributions and specification of the targets directly in terms of their spatial frequency spectra, permits one to examine the antenna images for quality and resolution. The results obtained indicate that resolution for a class of ground targets can be much better than is predicted by the two-point Rayleigh resolution criterion. It is also true that there can be situations in which the shape of the antenna images are quite independent of the radiation pattern. Several types of spatial noise were also included in the input spectrum to investigate noise effects on image quality and resolution. (Author).
Author: J. F. McIlvenna Publisher: ISBN: Category : Aerial photography Languages : en Pages : 66
Book Description
The mapping of extended, cultural ground targets by an airborne radar is examined using communication theory concepts including those of the antenna transfer function and the target spatial frequency spectrum. Use of the set of transfer functions that correspond to Taylor aperture distributions and specification of the targets directly in terms of their spatial frequency spectra, permits one to examine the antenna images for quality and resolution. The results obtained indicate that resolution for a class of ground targets can be much better than is predicted by the two-point Rayleigh resolution criterion. It is also true that there can be situations in which the shape of the antenna images are quite independent of the radiation pattern. Several types of spatial noise were also included in the input spectrum to investigate noise effects on image quality and resolution. (Author).
Author: F. V. Schultz Publisher: ISBN: Category : Boundary value problems Languages : en Pages : 14
Book Description
In this work, rigorous electromagnetic theory is used to determine the nose-on radar cross section of a perfectly conducting cone of finite height. The end cap of the cone is assumed to be a segment of a s spherical surface with center at the apex of the cone. Numerical results have been obtained for a cone having a total apex angle of 30 degrees and for values of [kappa alpha] ranging from 0.0259 to 5.18, where [kappa]=2 [pi]/[lambda] and [alpha] is the radius of the base of the cone. Siegel's Rayleigh method and by using Keller's modified geometrical optics as well as with experimental results obtained by Keys. The comparisons are instructive below [kappa alpha] = 3.2, the apparent upper limit of validity of the present results -- p.[3].
Author: Edward E. Altshuler Publisher: ISBN: Category : Astronautics Languages : en Pages : 46
Book Description
It is expected that with the exploration of outer space, a requirement for high data rate earth-to-space communication channels will arise. A program to investigate the feasibility of using the millimeter-wave region of the spectrum for this application is presented. The theory of atmospheric attenuation resulting from losses due to absorption, scattering and refraction processes is reviewed and used to estimate propagation losses produced by atmospheric gases, clouds and precipitation. Curves of total atmospheric attenuation and noise level as a function of meteorological parameters and antenna elevation angle are also presented. A series of experiments designed to obtain as much information as possible on the limitations imposed by the atmosphere on millimeter-wave propagation is considered. Although experiments using natural celestial bodies such as the sun, moon, planets and galaxies as radio sources are emphasized, those which would utilize aircraft, rockets and satellites are also mentioned. Finally, the characteristics of a recently installed precision 29-ft antenna designed to operate at 35 Gc (wavelength = 8.6 mm) with a traveling-wave maser as a preamplifier for the radiometer are outlined along with the specific experiments for which this antenna system will be used. (Author).
Author: C. C. Leiby (Jr.) Publisher: ISBN: Category : Electrophoresis Languages : en Pages : 42
Book Description
Druyvesteyn's solutions for electrophoretically induced gas flows in electrical discharges in gases were extended over a larger pressure range and corrected for the influence of Debye shielding effects. The effects of molecular or 'slip' flow were also taken into account. These more accurate and general solutions were applied to the reverse phenomenon of space charge field generation arising from the flow of a thermally ionized cesium plasma through a tube. Under such flow conditions, a non-linear differential equation for the axial pressure distribution was obtained but not solved. However, it was possible to obtain estimates of the ranges of cesium pressure, temperature and tube radii which would be required for sensible levels of electric power generation. Anaphoretic flow power levels of the order of 0.1 to 10 watts, in tubes of laboratory dimensions (radii of 10 cm or less), appear feasible at temperatures from 1700 to 2400K. Sensible power generation levels at lower temperatures require very large diameter tubes, and therefore are not feasible. (Author).
Author: Daniel J. Jacavanco Publisher: ISBN: Category : Antennas, Horn Languages : en Pages : 22
Book Description
Antenna patterns (E-plane) of an X-band horn mounted in a ground plane and covered by a plasma slab were measured. A pulsed plasma was produced by capacitor discharge in a rectangular pyrex container of 6 in. x 2 in. x 24 in. i.d. Microwave interferometer measurements of the electron density were made at 9 and 35 Gc. Antenna patterns are presented which show a sharp decrease in radiated power at certain angles corresponding to the 'optics critical angle'. Good agreement is obtained for the movement of the optics critical angle with plasma density. (Author).
Author: J. F. McIlvenna
Author: J. F. McIlvenna
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Author: P. Blacksmith (Jr.)
Author: F. V. Schultz
Author: Edward E. Altshuler
Author: C. C. Leiby (Jr.)
Author: Daniel J. Jacavanco