{"title":"Beam Efficiency Limitations of Large Antennas","authors":"R. T. Nash","doi":"10.1109/TME.1964.4323152","DOIUrl":"https://doi.org/10.1109/TME.1964.4323152","url":null,"abstract":"The beam efficiency of an antenna may be defined as the ratio of the power radiated within the main beam to the total power radiated. The beam efficiency is derived for ideal rectangular and circular apertures, as a function of the edge-to-center amplitude ratio. Random phase errors are assumed to exist across the aperture. Various types of feeds for parabolic reflectors are also considered in relation to the fraction of power which the feed directs into the paraboloid. A primary limitation on the beam efficiency of a paraboloid is shown to be produced by the surface roughness.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116737680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radio Astronomy Receivers","authors":"M. Tiuri","doi":"10.1109/TME.1964.4323154","DOIUrl":"https://doi.org/10.1109/TME.1964.4323154","url":null,"abstract":"A general survey of the principles of radio astronomy receivers is presented. System noise temperature, the sensitivity of different receiver types, and the calibration of receivers are studied. A total-power receiver is analyzed as a basic radio telescope receiver and. the results are used to obtain the performance of other receiver types such as the Dicke receiver, Graham's receiver, correlation receiver, and phase-switching receiver.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122064557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radar Investigations of the Planets","authors":"R. Goldstein","doi":"10.1109/TME.1964.4323145","DOIUrl":"https://doi.org/10.1109/TME.1964.4323145","url":null,"abstract":"Planetary radar astronomy's greatest handicap is the extremely feeble power content of an echo. This echo is always masked by relatively strong background noise so that special signal processing is required. The basic task is the detection and measurement of the echo power. However, when the signal strength is greater than the requirements of simple detection, it is desirable to measure the power distribution in time or in frequency. When the signal is still stronger, it is possible to divide the power into the two dimensions of time delay and frequency shift simultaneously, and thus produce a radar \"map\" of the target. Some of the special techniques and devices which are required to make these measurements, as well as some of the results of applying these techniques to Venus, Mars, Mercury, and Jupiter, are described. There are several groups working in this field and the author has stressed the work at the Jet Propulsion Laboratory merely because of his familiarity with it.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129503572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Structure of the Galaxy from Radio Observations","authors":"G. Westerhout","doi":"10.1109/TME.1964.4323157","DOIUrl":"https://doi.org/10.1109/TME.1964.4323157","url":null,"abstract":"The appearance of our Galaxy at radio wavelengths can be described as follows: The Milky Way stands out as a bright band of emission, at both long and short wavelengths. Above 50 cm, radio emission from the rest of the sky can also be observed. The brightness distribution is highly irregular. It can be interpreted as being due to the following sources: 1) Emission from ionized gas in the galactic plane, prominent at short wavelengths. 2) Synchrotron emission from the galactic disk and the Halo, prominent at long wavelengths. It is proposed that the sources of this nonthermal emission are clouds of relativistic particles and magnetic fields, possibly supernova remnants, distributed through the spiral arms and up to some distance from the galactic plane. The 21-cm line emitted by neutral hydrogen permits the astronomer to obtain a picture of the spiral structure and to study the motions of both the gas and the Galaxy as a whole. The galactic center and its surroundings poses a problem in itself, showing structure remarkable in both the continuum emission and in the neutral hydrogen distribution. Its structure suggests the possibility of an explosion of the galactic nucleus in the past.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122689701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermal Galactic Sources","authors":"T. K. Menon","doi":"10.1109/TME.1964.4323151","DOIUrl":"https://doi.org/10.1109/TME.1964.4323151","url":null,"abstract":"Celestial radio sources have generally been divided into two categories: 1) thermal sources, and 2) nonthermal sources. The thermal sources are usually masses of ionized hydrogen and their radiation is due to the random interaction of the electrons and protons of the ionized gas. The major cause of ionization is the ultraviolet radiation of the hot stars. This paper describes the basic physical processes involved in the radiation, and the methods of obtaining information from radio observations about the interstellar medium and the hot stars.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114472186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hectometer Cosmic Static","authors":"G. Reber","doi":"10.1109/TME.1964.4323153","DOIUrl":"https://doi.org/10.1109/TME.1964.4323153","url":null,"abstract":"A review is made of radio astronomy development starting with Jansky at 15-m wavelength and progressing to 30, 60, 144, 576, and 2100 m. Electromagnetic wave propagation through the ionosphere by the O, X, Z, and Y modes including various aberrations is discussed. Methods of overcoming atmospherics are outlined. Preliminary findings at hectometer waves and the cosmological implications are mentioned. The different outlook upon the structure of the universe appears to be a more enticing aspect of the study than details about the contents of the Milky Way. Equipment technology is entirely omitted. A comprehensive list of references to the literature is included, along with four figures.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114317305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radar Backscatter from the Earth's Ionosphere","authors":"W. Gordon","doi":"10.1109/TME.1964.4323146","DOIUrl":"https://doi.org/10.1109/TME.1964.4323146","url":null,"abstract":"The role of radar backscatter observations in ionospheric studies is outlined. The theoretical developments are described that form the basis for ground-based measurements of electron density, electron temperature, ion temperature, and ionic composition at ionospheric heights. Observations of the first three parameters have been successful. Observation of the fourth parameter, ionic composition, is a challenging problem and is being attempted.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128972375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radio-Telescope Antenna Parameters","authors":"H. Ko","doi":"10.1109/TME.1964.4323148","DOIUrl":"https://doi.org/10.1109/TME.1964.4323148","url":null,"abstract":"Principal antenna parameters which are useful in characterizing the electrical performance of radio-telescope antennas are defined and the relations between them are established. The application of these parameters to radio astronomical measurements is discussed.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114522496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radar Echoes from the Sun","authors":"J. James","doi":"10.1109/TME.1964.4323147","DOIUrl":"https://doi.org/10.1109/TME.1964.4323147","url":null,"abstract":"The study of the sun by radar which was begun less than five years ago should become a valuable supplement to the study, by other methods, of the sun and interplanetary space. High powered transmitters and large antennas are required to detect a solar echo. Frequencies less than 50 Mc should be optimum, primarily because of increasing coronal absorption with increasing frequency. Routine observations were begun by the Lincoln Laboaratory of the Massachusetts Institute of Technology in April, 1961, at a site near El Campo, Texas. Observations since that time have been made on about 200 days per year. The transmitter has an average power output of 500 kw and operates at a frequency of 38.2 Mc. The system includes two cross-polarized antennas consisting of large arrays of dipoles. These antennas have maximum gains of 33 and 36 db. The received solar echo is usually 20 to 30 db below the solar noise and signal integration is required to detect the echo. The average measured solar radar cross section is approximately equal to that of the projected area of the photosphere although there are large fluctuations about the mean. Some possible reasons for these variations in cross section are discussed. The Doppler spreading of the solar echoes varies between 20 and 70 kc and is apparently due to mass motions on the sun. These indicated mass motions are large enough to affect the coronal temperature measurements made by the emission-line broadening method.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123971760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Measurements of Radio Star and Satellite Scintillations at a Subauroral Latitude","authors":"R. Allen, J. Aarons, H. Whitney","doi":"10.1109/TME.1964.4323140","DOIUrl":"https://doi.org/10.1109/TME.1964.4323140","url":null,"abstract":"Observations of two radio stars, Cygnus A and Cassiopeia A, and of two satellites, Cosmos I and Transit 4A, have yielded data on lower and upper atmospheric irregularities. The frequencies studied have included 20 Mc, 40 Mc and 54 Mc for satellite transmissions, and 30 Mc to 3000 Mc for radio star signals. The antennas used have ranged from a dipole to a 150-foot parabola. The irregularities in refractive index in the lower atmosphere produce amplitude fluctuations up to several times average with a fading rate of 3 to 0.5 per minute while ionospheric amplitude fluctuations can increase several decibels, with rates from 1 to 60 per minute. Lower atmosphere scintillation rates increase as the elevation angle increases and generally disappear above 50 of elevation. During intense magnetic storms, the ionospheric scintillation rate is a function of wavelength in the UHF range. Ionospheric scintillations are functions of both magnetic conditions and of the subionospheric latitudes of the irregularities; they are observed at zenith at the geomagnetic latitude of the Sagamore Hill Radio Observatory (54°). Using spaced receivers, heights of single irregularities have ranged from about 100 to 600 km and representative sizes from about 0.1 to 4 km. Irregularities constitute the prime factor affecting the level, phase and angle of arrival of signals propagated through the auroral regions.","PeriodicalId":199455,"journal":{"name":"IEEE Transactions on Military Electronics","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1964-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127582300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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