Download or read book An Evaluation of Two Millimeter Wave Propagation Models for Horizontal Atmospheric Attenuation at 70 115 GHZ written by and published by . This book was released on 1988 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: An evaluation is performed for two millimeter wave propagation models: the LIEBE model, developed at the Institute for Telecommunications, Boulder, CO, under the guidance of Dr. H. Liebe; and the EOSAEL model, developed at the US Army Atmospheric Laboratory at White Sands Missile Range, NM. This evaluation is conducted for horizontal attenuation due to both clear atmosphere and hydrometer effects under typical surface meteorological conditions, and within the frequency range 70-115 GHz. Intercomparisons of model theories and predictions show slight differences for molecular oxygen and fog attenuations, but significant differences for water vapor and rain attenuations. Results indicate that, while the qualitative agreement between either the EOSAEL or LIEBE model predictions, and measurements, for horizontal attenuation due to oxygen, water vapor, fog and rain is certainly satisfactory, there is a definite need for improvement. Overall, no clear preference for either the EOSAEL or LIEBE model for operational use is ascertained. Data comparisons suggest that, for several attenuation types, model preference is dependent on either the frequency or meteorological conditions.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1988 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1988-07 with total page 534 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 1988 with total page 1424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Use of Services for Family Planning and Infertility United States 1982 written by Gerry E. Hendershot and published by . This book was released on 1988 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1982 statistics on the use of family planning and infertility services presented in this report are preliminary results from Cycle III of the National Survey of Family Growth (NSFG), conducted by the National Center for Health Statistics. Data were collected through personal interviews with a multistage area probability sample of 7969 women aged 15-44. A detailed series of questions was asked to obtain relatively complete estimates of the extent and type of family planning services received. Statistics on family planning services are limited to women who were able to conceive 3 years before the interview date. Overall, 79% of currently mrried nonsterile women reported using some type of family planning service during the previous 3 years. There were no statistically significant differences between white (79%), black (75%) or Hispanic (77%) wives, or between the 2 income groups. The 1982 survey questions were more comprehensive than those of earlier cycles of the survey. The annual rate of visits for family planning services in 1982 was 1077 visits /1000 women. Teenagers had the highest annual visit rate (1581/1000) of any age group for all sources of family planning services combined. Visit rates declined sharply with age from 1447 at ages 15-24 to 479 at ages 35-44. Similar declines with age also were found in the visit rates for white and black women separately. Nevertheless, the annual visit rate for black women (1334/1000) was significantly higher than that for white women (1033). The highest overall visit rate was for black women 15-19 years of age (1867/1000). Nearly 2/3 of all family planning visits were to private medical sources. Teenagers of all races had higher family planning service visit rates to clinics than to private medical sources, as did black women age 15-24. White women age 20 and older had higher visit rates to private medical services than to clinics. Never married women had higher visit rates to clinics than currently or formerly married women. Data were also collected in 1982 on use of medical services for infertility by women who had difficulty in conceiving or carrying a pregnancy to term. About 1 million ever married women had 1 or more infertility visits in the 12 months before the interview. During the 3 years before interview, about 1.9 million women had infertility visits. For all ever married women, as well as for white and black women separately, infertility services were more likely to be secured from private medical sources than from clinics. The survey design, reliability of the estimates and the terms used are explained in the technical notes.
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1988 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atmospheric Propagation Properties in the 10 to 75 GHz Region written by Institute for Telecommunication Sciences and published by . This book was released on 1969 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The expansion of telecommunication services into the millimeter wave region prompts a careful look at the limitations of the atmosphere that can give rise to severe signal degradations. In Part I the loss and scatter mechanisms in the 10- to 40- GHz range are examined. It is concluded that there is a need for further theoretical and experimental work on the atmospheric propagation properties in order to support the engineering efforts in designing reliable, useful systems. In Part II the discussions are extended to the 40- to 75 -GHz region where absorption by oxygen dominates. In this region, communication through the atmosphere is not practical; however, the oxygen absorption has a great potential for remote sensing of atmospheric variables, and for special (short-range communication) applications. Unsolved problems of the propagation medium are discussed as a basis for formulating proposals; and the objectives of an experimental program for studying oxygen dispersion and absorption are given.
Download or read book Millimeter wave Propagation in Moist Air written by and published by . This book was released on 1985 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Attenuation and Phase Dispersion Between 40 and 140 GHz for Path Models from Different Altitudes written by Hans J. Liebe and published by . This book was released on 1973 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1988 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling System Performance Throughout the Millimeter Wave Band written by L. G. Mundie and published by . This book was released on 1978 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Atmospheric Millimeter Wave Propagation Model written by Hans J. Liebe and published by . This book was released on 1984 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Conference on Optical and Millimeter Wave Propagation and Scattering in the Atmosphere Florence Italy May 27 30 1986 written by International Conference on Optical and Millimeter Wave Propagation and Scattering in the Atmosphere 1986, Firenze and published by . This book was released on 1986 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography on Propagation Effects from 10 GHz to 1000 THz by L E Vogler and S F Van Horn written by Lewis E. Vogler and published by . This book was released on 1972 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AGARD Conference Proceedings written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scattering of Millimeter Waves in Line of sight Propagation written by Alan T. Waterman and published by . This book was released on 1975 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Line-of-sight propagation measurements at 34.89 GHz and 11.63 GHz on a 28 km path are analyzed with particular emphasis on (a) transmissable bandwith and (b) the effects of rain. Bandwidth studies are approached by measuring the frequency covariance of the 3:1 frequency ratio employed, and then using the theory of weak scattering to infer the covariance of signal fluctuations at lesser frequency separations. The conclusions reached from this approach indicate negligible bandwith limitations for bandwidths of a few per cent (300-400 MHz, at 35 GHz), as a consequence of single scattering processes; i.e., the inferred frequency covariance between extremes in the band should exceed 0.95. The effects of rain, while showing up markedly in attenuation at the higher frequency, do not have other consistently deleterious consequences. Angle-of-arrival jitter is relatively unaffected. Frequency covariance is more erratic during squally weather but tends to rise during times of heavy rain.
Download or read book Atmospheric Effects on Near Millimeter Wave Propagation written by R. A. Bohlander and published by . This book was released on 1985 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Utilization of the near-millimeter-wave band is limited by atmospheric effects of propagation. Although this paper is restricted to clear-air effects, it is pointed out that these phenomena, which are molecular in origin, are also present to a significant degree in adverse weather. The paper surveys theoretical and observational knowledge concerning absorption, emission, refraction, and turbulence effects in clear air and in the spectral range 90 to 1000 GHz. Modeling practices are also reviewed. Keywords include: Wave propagation; Near millimeter waves; Emission; Refraction; Turbulence; Atmosphere; and Molecular absorption.
