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Antennas and Propagation, Transactions of the IRE Professional Group on

Volume 3: 1952

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Displaying Results 1 - 25 of 47
  • Investigation of a surface-wave line for long distance transmission

    Publication Year: 1952 , Page(s): 263 - 267
    Cited by:  Papers (1)
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  • Guided wave concept in electromagnetic theory

    Publication Year: 1952 , Page(s): 231 - 239
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  • Theory of radio scattering from the aurora

    Publication Year: 1952 , Page(s): 217 - 230
    Cited by:  Papers (4)
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  • Continental maps of four ionosphere disturbances

    Publication Year: 1952 , Page(s): 214 - 216
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  • Scatter-sounding: A technique for study of the ionosphere at a distance

    Publication Year: 1952 , Page(s): 186 - 201
    Cited by:  Papers (4)
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  • The effect of particle shape and composition on microwave attenuation and scattering by precipitation

    Publication Year: 1952 , Page(s): 180 - 185
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  • Transmission loss of space waves propagated over irregular terrain

    Publication Year: 1952 , Page(s): 152 - 166
    Cited by:  Papers (3)
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  • Some methods for evaluating trends in time series of tropospheric radio field strength data

    Publication Year: 1952 , Page(s): 144 - 151
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    This paper presents a short review of several methods for evaluating the "seasonal trend" in a series of hourly median field strengths corresponding to one hour of the day. The presentation is from the viewpoint of descriptive statistics, and no discussion is given of the difficult problem of statistical tests of significance for appraising the components of trend found by these methods. Of three methods investigated in CRPL, a type of harmonic analysis was found to be the most successful. The other two methods were an adaptation of the smoothing theory of Wiener and Levinson and a method using orthogonal polynomials. The tools of the statistician, the autocorrelation function and the variate difference method, enable us to refine our analysis of time trends to a point where we hope to obtain a maximum amount of correlation with similar trends in relevant meteorological information. View full abstract»

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  • Upper atmosphere physical characteristics

    Publication Year: 1952 , Page(s): 4
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    Recent physical data concerning the constitution of the upper atmosphere and solar emissions are used in a discussion regarding some properties of the ionospheric regions. Numerical values are given for the electron collision frequency as a function of height. The transition region of dissociation of molecular oxygen is considered and the dissociation of molecular nitrogen is studied. Diffusive separation is shown to contribute to the vertical distribution of the atmospheric constituents. The penetration of relevant solar radiation is discussed with respect to the formation of ionospheric layers. View full abstract»

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  • Low frequency propagation in an exponential ionospheric layer

    Publication Year: 1952 , Page(s): 126 - 136
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  • Concerning the radio field due to internal reflections in the stratified troposphere

    Publication Year: 1952 , Page(s): 117 - 125
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  • Turbulence in the lower ionosphere as deduced from increments in absorption and phase path at 150 KC

    Publication Year: 1952 , Page(s): 139
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    It is important in the study of ionospheric winds to determine the height of the "diffraction screen" which produces the variations in radio wave field strength, or other characteristics, measured at ground level. A method which may be used to determine this height is developed. It is shown that, under proper conditions, the mean electronic collisional frequency associated with the electron clouds which are presumed to form the "diffraction screen" may be determined by studying change in phase path records obtained simultaneously with absorption records. This value of collisional frequency may then be related to height through an ionospheric model. Single recording stations are used in this comparison of the phase pattern and the amplitude pattern at ground level. The statistical information necessary to the theoretical development is obtained, in the usual way, from a triangular arrangement of receiving stations which record the amplitude of the signal. Preliminary calculations show that the screen which produces the daytime ionospheric winds measured at 150 kc lies in a collisional frequency range from 2 \times 10^{6} to 8 \times 10^{6} sec-1. This would correspond to a height range from 70 to 80 km for our ionospheric model. These results appear to be in good agreement with recent work by Kellogg (1951) from the meteorological viewpoint. View full abstract»

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  • Distant radio communication theory

    Publication Year: 1952 , Page(s): 212
    Cited by:  Papers (2)
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    Distant radio communication at high frequencies is difficult because the transmission medium, the earth ionosphere duct, is time variable, noisy, and shows dispersive or multipath transmission with consequent fading of the received signal. Because most of these factors are random and not under design control, one can treat the ionospheric communication problem only on a statistical basis in terms, for example, of such things as the probability that a transmitted pulse or bit of information will be received correctly. On this basis it is shown that, by a purely numerical experiment wherein random number tables are used to simulate fading and noise, it is possible to appraise various telegraph transmission systems without the costly process of building them and then testing their performance. An approximate, but simple, analysis is given of receiver signal detection, by which is meant generation of dc for operation of an output printing device. It is shown that the important parameter here is the average or expectation of the difference in dc between a received space and mark signal, divided by the square root of the variance of this difference. Incoherent square law detection is compared with coherent detection using the matched filter or, what is the same thing, correlation. The use of diversity transmission to overcome signal fading at the receiver is considered. The important statistical data regarding time-varying ionospheric transmission are obtained from the auto- and cross-correlation functions of the received signal envelopes for the various diversities. For the correlated fading of signal s in two transmission channels, a simple de sign formula is shown which predicts the improvement in the use of diversity. A brief description is also given of a simple acoustic ionosphere analog simulating time-varying multipath transmission. View full abstract»

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  • F-region effects of solar eclipse at sunrise, September 1 , 1951

    Publication Year: 1952 , Page(s): 210
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    The annular eclipse of September 1, 1951 started before ground surmise along the east coast of the United States but did not reach maximum phase until later. Three high-speed ionospheric stations were operated by the D.T.M., C.I.W. for the eclipse observations. Locations at Charlottesville, Virginia, Derwood, Maryland, and Chincoteague, Virginia established a west-to-east chain with local time difference of approximately twelve minutes. The maximum phase of eclipse occurred at a time (twenty to thirty minutes after ground sunrise) when normal rate of production of ionization (established by control observations) was very high. The results show absence of any ion production at any station for a period of approximately one-half hour centered on time of eclipse maximum. From the moment when two-thirds of the sun was covered, through the maximum phase ( \pm 94 per cent), and until one-third of the sun was uncovered, no ionization was generated. Several possible explanations are discussed: (1) Emitting sources near center of sun's disc; (2) Uniform solar emission, but an effective limb darkening; (3) An atmosphere on the moon. View full abstract»

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  • Theory of waveguide-fed slots radiating into parallel-plate regions

    Publication Year: 1952 , Page(s): 63 - 66
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    Slotted waveguide arrays feeding into parallel-plate regions have been used in some high speed scanners. Parallel-plate regions also have been used for the suppression of second-order beams of high-gain arrays. A theoretical expression is derived for the conductance of a longitudinal shunt-slot in a rectangular guide when the slot is radiating into a parallel-plate region of arbitrary plate spacing. Some peculiarities of the theoretical results are discussed. There is good agreement between theory and experiment. View full abstract»

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  • Measurement of the effect of irregular terrain on VHF and UHF directive antenna patterns

    Publication Year: 1952 , Page(s): 167 - 178
    Cited by:  Papers (4)
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    Measurements of antenna patterns of directive antennas were made while driving around transmitters at relatively constant distances of 0.4, 10, and 30 miles. The transmitting antennas for pattern measurement were located at Fort Dix, N.J., and operated at frequencies of 49, 141.75, 239, and 460 mc. The receiving antennas used for recording were ground-plane antennas mounted on a retractable mast in the mobile recording unit and could be operated as high as 30 feet, road obstacles permitting. Because of the great number of wires and trees over the road, most measurements were made at 12 and 15 feet. In addition to the measurements made around the transmitters, receiving antenna pattern measurements were made at spot locations around the transmitter with a 460-mc corner reflector antenna. View full abstract»

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  • The polarization ellipse in the ionosphere

    Publication Year: 1952 , Page(s): 50 - 52
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  • Sporadic-E stratification and correlation with low-frequency soundings

    Publication Year: 1952 , Page(s): 140 - 142
    Cited by:  Papers (1)
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  • Theoretical and experimental investigation of the group heights of reflection of 150-KC radio waves vertically incident on the ionosphere

    Publication Year: 1952 , Page(s): 136 - 137
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    This paper is concerned with the theoretical and experimental determination of the group heights of reflection of long radio waves vertically incident on the ionosphere. The theoretically expected group heights for 250-microsecond Gaussian shaped pulses are determined utilizing: (1) a wave theory treatment including coupling, (2) a Chapman-like ionospheric model including all variables and their height variations and (3)a fundamental radio frequency or carrier component of 150 kc. From the theoretical viewpoint the continuous wave (cw) results of Gibbons and Nertney(1951) (1952) are extended by including the dispersive characteristics of the above model. This is accomplished by determining the received pulse characteristics by means of a response function developed from a suitable Fourier-Hermite series which includes the frequency dependent effects of the model. It is Found that the rapid changes in polarization near the lower edge of E-region, called the "coupling region", are very effective in generating reflected waves or pulses under suitable conditions; i.e., late night hours associated with low E-layer critical Frequencies. However, the dispersive characteristics are small so that almost negligible group retardation is to be expected. At a higher level in the layer, rapid variations in the index of refraction for one of the characteristic wave components occur in what is called the "reflection region". Here the time delays are large for low critical frequency models. Some geometrical discussion is included concerning polarization and coupling Factors. If not considered, then the ordinary and extraordinary modes can be given a representation (in a certain complex space) as orthogonal principal directions. The above theory is compared with the experimentally observed group heights on a diurnal and seasonal basis. Good agreement is obtained and is further strengthened by comparison with some recent measurements of R.E. Jones on the diurnal change in phase (cw) paths. The occurrence of a third echo in addition to the regular First hop E-echoes is reported. This apparently occurs from levels above the maximum ionization density of the E -layer, height range 100 to 200 km, and appears to be associated with low nighttime E -layer- critical frequencies and magnetically disturbed conditions. Correlations of experimental results with sunrise, solar flares, etc. are also considered. View full abstract»

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  • Relationships between auroras and sporadic-E echoes

    Publication Year: 1952 , Page(s): 213
    Cited by:  Papers (2)
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    During March, 1951, a series of visual auroral observations were made simultaneously with ionospheric soundings at Point Barrow, Alaska. Observations were made every 15 minutes during the dark hours of ten successive clear nights. Some 400 simultaneous observations were made. Auroras were present during about 90 per cent of these observations. Analysis indicates that quiet auroras 45\deg or more above the horizon, were correlated with certain sporadic-E region echoes. The more intense the aurora, the higher the maximum frequency returned. The closer the auroral form was to the zenith, the shorter the range of the "Es" echoes. Active auroral displays were usually accompanied by a sharp increase in radio wave absorption. Local geomagnetic variations coincident with auroral displays were also examined. View full abstract»

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  • Ionosphere reflection coefficients by variational technique

    Publication Year: 1952 , Page(s): 211
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    One of the important problems of ionosphere work is to predict the nature of the electromagnetic wave reflected by the ionosphere when a wave of known form is incident upon it. In the present paper, this problem is treated by considering a plane ionosphere model for which the electron density and earth's magnetic field are continuous but otherwise arbitrary functions of the height. It is shown that if a plane wave impinges on such a model at an arbitrary angle of incidence, then four complex reflection coefficients suffice to characterize the reflected wave as to its intensity, phase, and polarization. Thus the problem becomes one of the calculating of these four numbers. The attack on this problem is based on an adaptation of a method due to the physicist, J. Schwinger, wherein, with the aid of an exact integral equation for the electric field in the ionosphere, one derives variational formulas for the four reflection coefficients. These formulas may then be used either to calculate the coefficients numerically or to obtain approximate expressions for them in terms of the various physical parameters of the problem. Finally, as a consequence of a certain symmetry property of the variational formulas, a reciprocity theorem for ionospheric propagation is deduced. View full abstract»

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  • Control of annular slot excitation by selective dielectric filling

    Publication Year: 1952 , Page(s): 53 - 59
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  • Short-period sky-wave fading of CW emissions

    Publication Year: 1952 , Page(s): 12 - 18
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    A study of the short-period sky-wave fading of cw emissions shows that observed characteristics of these fading distributions are functions of the relative amplitudes of the received and magneto-ionic components. When the received magneto-ionic components are essentially equal at the receiving point, severe and rapid fading occurs and variations in short-period fading are maximum. However, when a single mode of propagation is suppressed, the variations in short-period fading distributions of the received field are reduced and become lognormal in character. A new parameter is suggested to replace the Rayleigh distribution in cases where a more accurate formulation of short-period fading characteristics is desired. Finally, a description is given of a practical method of emitting cw radio transmissions, which yields reflections from the ionosphere of a single ionospheric mode, thereby obtaining some man-made control over short-period sky-wave fading. View full abstract»

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  • Characteristic waves

    Publication Year: 1952 , Page(s): 25 - 32
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    The familiar quasi-homogeneous (ray) treatment of the ionosphere shows that in a slowly varying ionosphere there are two and only two possible types of independent propagating waves called the magneto-ionic components. In the case of normal incidence, these components have the well-recognized property that the polarization of a reflected wave of one type is identical to that of an incident wave of the same type. However, it does not seem to have been appreciated that, in general, for linear anisotropic reflecting media of any degree of inhomogeneity, there exist two and only two characteristic polarizations having the latter property. It is shown that the characteristic polarizations can be determined from three experiments in which three different known polarizations are transmitted and the resulting reflected polarizations are measured. The information thus obtained is also sufficient to determine the ratio Of the reflection coefficients of the two characteristic waves. In the special case of the homogeneous ionosphere it is shown that the number of experiments of the above type can be reduced to two. View full abstract»

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  • Factor of merit for aircraft antenna systems for the frequency range from 3 to 30 MC

    Publication Year: 1952 , Page(s): 67 - 73
    Cited by:  Papers (3)
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Aims & Scope

This Transactions ceased publication in 1955. The current retited publication is IEEE Transactions on Antennas and Propagation.

Full Aims & Scope