Download or read book Influence of Non Homogeneous Earth on the Performance of High Frequency Receiving Arrays with Electrically Small Ground Planes written by and published by . This book was released on 1991 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of ground-based frequency (HF) antenna arrays is reduced when the array elements have electrically-small ground planes. Performance degradations include: (1) a decrease in directive gain near the horizon (caused by earth multipath), (2) a decrease in radiation efficiency and an increase in internal noise (caused by ground losses), (3) an array RMS phase error (caused by exterior currents on element feed cables), and (4) an array rms phase error and beam pointing errors (caused by non-uniform Fresnel reflection RMS from a non-homogeneous earth). This paper models the degradation described in (4) above. Numerical results are presented for cases of randomly-distributed and systematically-distributed earth non-homogeneities where one-half of vertically-polarized array elements are located in proximity to one type of earth and the remaining half are located in proximity to a second type of earth. The maximum rms phase errors, for the cases examined, are 18 degrees and 9 degrees for randomly-distributed and systematically-distributed non-homogeneities, respectively. The maximum beam pointing errors are 0 and 0.3 beamwidths for randomly-distributed and systematically-distributed non-homogeneities, respectively.

Download or read book Performance of Ground Based High Frequency Receiving Arrays with Electrically Small Ground Planes written by and published by . This book was released on 1991 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrically-small ground planes degrade the performance of ground-based high-frequency receiving arrays because the arrays are more susceptible to earth multipath, ground losses, and external currents on element feed cables. Performance degradations include a reduction in element directive gain near the horizon, distortion of the element azimuthal pattern, an increase in the system internal noise factor, and increases in the array factor root-mean-squared (rms) phase error and beam-pointing errors. The advantage of electrically-small ground planes is their relatively low cost of construction and maintenance.

Download or read book Monopole Antennas written by Melvin M. Weiner and published by CRC Press. This book was released on 2003-04-22 with total page 733 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text provides discussion of the modelling, testing and application of monopole antennas in free space and in proximity to flat earth, including topics on propagation, tuning stability, antenna range design, noise, ground-based high-frequency arrays, and electrically small antennas.

Download or read book Radio Science written by and published by . This book was released on 1994 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1991 with total page 1656 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book Performance of Electrically Small Beamed Array Receiving Systems in the Presence of Noise written by Martin Fournier and published by . This book was released on 1967 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of broadband, electrically small beamed receiving arrays operating in the high frequency band (3 to 30 MHz) and in a random noise environment is studied. The concepts of System Noise Figure (SNF) and Signal-to-Noise ratio Improvement Factor (SNIF) are proposed as criteria for comparing one array antenna receiving system to any reference system when the conditions of operation are defined. Graphical representations of SNIF for the two-element and the four-element antenna systems versus a single element system are presented. The improvement factor (SNIF) is shown to depend on the geometry of the array, on the phasing network and on the ratio of atmospheric noise power to internal system noise power. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1971 with total page 1330 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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Download or read book Proceedings of the IRE written by and published by . This book was released on 1959 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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