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Antennas and Propagation, Transactions of the IRE Professional Group on

Volume PGAP-4: 1952

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Displaying Results 1 - 25 of 27
  • The design of circularly polarized aperture antennas

    Publication Year: 1952 , Page(s): 136
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    By using equivalent circuits, the polarization transmitted from an aperture is analized in terms of the reflection properties of the aperture, the length of the Waveguide, and pertinent parameters of the exciting antenns. The techniques described afford a systematic procedure for designing antennas which are circularly polarized at one frequency or which have a low axial ratio over a band of frequencies, This procedure may be used to solve which have been applicable to lessless antennas are derived. Systems for measuring all pertinent parameters are developed and theoretical predictions are correlated with experimental measurements. View full abstract»

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  • Multiple unit antennas, with skew

    Publication Year: 1952 , Page(s): 136
    Cited by:  Papers (1)
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    The number of antennas required to produce a satisfactory horizontal pattern around a relatively large support structure is reduced in a major degree by a new technique known as "skew". Calculated and measured patterns are discussed, comparing normal radially-directed units and those with 90-degree skew. The results with skew angles varying from 90 degrees down to zero are studied. The effects of progressive increase of structure size are shown. Variation with phasing is studied. A mathematical analysis is made for the purpose of disclosing the fundamental basis for pattern improvement by antennas mounted in a skewed relationship. View full abstract»

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  • A rotary joint for two microwave transmission channels of the same frequency band

    Publication Year: 1952 , Page(s): 136
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    This dual-channel rotary joint consists of two pairs of rectangular waveguide terminals, a circular waveguide which transmits both channels, and coupling elements between the rectangular waveguide terminals and the circular waveguide which convert the rectangular H10mode into the circular H01and E01modes. If pure H01and E01modes can be excited, perfect separation of the channels as well as-constant amplitudes and phases can be obtained when the Joint rotates. While the conversion into the circular E01mode is performed by a conventional method, a new method had to be developed for the conversion of the rectangular H10mode into the circular H01mode. View full abstract»

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  • Mechanical scanners for radar antennas

    Publication Year: 1952 , Page(s): 135
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    The mechanical scanner is the most versatile and widely used antenna system for airborne radar application. In general, its radiation characteristics are superior to those of electrical scanned systems. There are three basic types of scanners: The wigwag, spiral, and helical. These basic types of scanners, along with various modifications of each, are discussed and compared, insofar as possible, with other than mechanical scanners. Such characteristics as relative size weight, scanning speeds, broadband matching, absolute gain, half-power beamwidth, relative minor lobe intensity, and aperture efficiency are compared and general rules are submitted as to how to choose which type of scanner will best perform in a given type of service. View full abstract»

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  • Tracking noise measurements on a manual tracking radar

    Publication Year: 1952 , Page(s): 135
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    Tracking noise measurements have been made on a manual tracking, sector-scan radar, Methods have been devised to measure the operator's tracking error, which has been assumed to be the principal source of tracking noise. In tests made with an actual moving target, it is extremely difficult to distinguish between tracking errors and the true target motion. In order to measure error alone, a technique has been developed in which a fixed target is given, known artificial motion. In this manner tracking error can be recorded for various target courses and speeds. Rate tracking and aided tracking have been simulated to allow experimental determination of optimum values of such parameters as aided tracking time constant and control sensitivity. View full abstract»

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  • Application of matrices to the problem of transmission through a multi-layered dielectric wall

    Publication Year: 1952 , Page(s): 117 - 134
    Cited by:  Papers (1)
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  • Application of the microwave homodyne

    Publication Year: 1952 , Page(s): 110 - 116
    Cited by:  Papers (4)
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  • Impedance matching by means of nonuniform transmission lines

    Publication Year: 1952 , Page(s): 107 - 109
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    A transmission line of varying characteristic impedance is often used as a four-terminal microwave network for the purpose of matching a load having one impedance to a generator having a different impedance. My main point can be summed up by one equation, giving the value of the reflection coefficient at the input or source end of the transmission line. In this equation, x is distance measured along the transmission line, xS and xL are values of x at the generator and load ends of the line respectively, β is the phase constant, and Z0 is the characteristic impedance. View full abstract»

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  • Nodal shift impedance measurements in periodic waveguides

    Publication Year: 1952 , Page(s): 106
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    The nodal shift method of measuring the properties of a Coupling system connecting two transmission lines is a convenient and accurate method which does not require the existence of good terminations to match the lines. Using a generalized definition of impedance in a periodically loaded waveguide, such as is encountered in the Stanford linear accelerator or in traveling-wave tubes, this technique can be extended to determining the properties of a coupling system connected between a smooth waveguide and the periodic one, and when these are known, one can measure impedances in the periodic structure by observing those in the smooth guide. In addition, this impedance relation permits one to deduce the phase-shift constant of the structure at any frequency in the pass-band. View full abstract»

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  • Symmetrical waveguide junctions

    Publication Year: 1952 , Page(s): 106
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    Dicke and Kerns have shown that from a knowledge of the geometrical symmetry of a junction one can deduce the form of the scattering matrix. The synthesis problem; given a desired scattering matrix, to determine whether it is physically realizable in a symmetrical structure, and to find the possible structures, has not been solved completely, although several useful things can be said about the general problem. However, the number of cases that are ever likely to arise in practice is finite, and by solving the analysis problem for each of them and tabulating the results we have effectively given a "brute-force" solution of the synthesis problem for junctions of six or fewer waveguides. View full abstract»

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  • Modes in waveguides containing ferrites

    Publication Year: 1952 , Page(s): 104 - 105
    Cited by:  Papers (4)
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  • The use of ridge waveguide for scanners

    Publication Year: 1952 , Page(s): 103
    Cited by:  Papers (1)
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    Summary form only given, as follows. The use of ridge waveguide with a movable ridge has been proposed for a variable-phase scanner. There are mechanical and electrical problems with this system similar to those encountered in variable width waveguide scanners. Its scan is more restricted, but it does permit the use of longitudinal slots in the broadside of the guide. Expressions for the fields in the ridge waveguide are obtained by Hahn's method. Expressions are obtained also for the normalized shunt conductance of a narrow longitudinal slot of resonant length in the broad face of the guide opposite the ridge and for the characteristic impedance of the ridge waveguide. [NB: A manuscript annotationon the copy at hand states "see also Howery, R.W. 'An Improved Eagle Scanner - Proc. of Third Symposium on Scanning Antenns' - Nov 1950 (NRL ASTIA #134257 (C-6317) [Confidential] Bendix Dept 465 File #2241."] View full abstract»

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  • Further affects of manufacturing tolerances on the performance of linear shunt slot arrays

    Publication Year: 1952 , Page(s): 93 - 102
    Cited by:  Papers (4)
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  • Optimum design of linear arrays in the presence of random errors

    Publication Year: 1952 , Page(s): 81 - 92
    Cited by:  Papers (9)
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  • Astigmatic diffraction effects in microwave lenses

    Publication Year: 1952 , Page(s): 72 - 80
    Cited by:  Papers (1)
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  • On spherically symmetric lenses

    Publication Year: 1952 , Page(s): 66 - 71
    Cited by:  Papers (7)
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  • Variation of field intensity over irregular terrain within line of sight for the UHF band

    Publication Year: 1952 , Page(s): 53 - 65
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    Late in 1950 the US Federal Communications Commission (FCC) was faced with the problem of having to allocate television (TV) broadcast stations in the ultra high frequency (UHF) band from 300 to 900 mc/s. In order to make an intelligent allocation, some knowledge was necessary of the extent of television service to be expected for these UHF channels. Consequently, a series of statistical studies was made of the available data to derive some empirical propagation formulae and curves upon which the UHF allocation might be based. One of these studies was that of the variation in field intensity over irregular terrain which will be discussed in this paper. Of necessity a great many of the details of the study cannot be included here. Thse who desire these details are referred to the original FCC report. The variation of field intensity over irregular terrain within line of sight for the UHF-band has been studied. The factors which affect these variations and the relative reliability of these factors have been investigated, leading to resultant distributions of field intensity over irregular terrain, as described by figure 9. In addition, this distribution has been compared with that for the VHF band and it has been possible to extrapolate the results to cover the whole UHF television band from 300 to 900 mc/s. by using the distribution of Fig. 9 and correcting for frequency the overall median deviations from a reference [Fig. 11]. View full abstract»

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  • A new type of propagation

    Publication Year: 1952 , Page(s): 47 - 52
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    H. Alfven and others have shown that when a conducting fluid is placed in a magnetic field the interaction of the electromagnetic and hydrodynamic forces generates a new type of wave, the nagneto-hydrodynamic wave. Using a description of these waves in an ideal fluid as a prototype, we briefly discuss their properties for various types of conducting fluids. A list of references is given. View full abstract»

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  • Short period sky-wave fading of CW emissions

    Publication Year: 1952 , Page(s): 46
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    A study of short, period sky-wave fading of CW emissions shows that observed characteristics are functions of the relative amplitude of the received and magnetoionic components. When the received magnetoionic 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 apractical 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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  • Microwave radio reflection from ground and water surfaces

    Publication Year: 1952 , Page(s): 37 - 45
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    Reflection of microwaves from ground and water surfaces for a number of wavelengths between 0.86 and 26.5 centimeters have been measured over paths of a few thousand feet and grazing angles of the reflected ray up to 5 degrees. Antennas with comparable patterns large enough to illuminate a large surface area were used. A variety of surface conditions including bare ground and smooth and choppy water were studied. For the particular overland path used, the ground appeared smooth at 26.5 and 9 centimeters wavelength, evidenced considerable roughness to 3.2 centimeters and appeared very rough to 0.86 centimeters. The mean reflection coefficient decreased with decreasing wavelength. For the overwater paths, the reflection for all wavelengths was that associated with a smooth surface when the conditions were calm. For a choppy surface, the millimeter signal showed large time variations and its apparent reflection coefficient decreased. View full abstract»

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  • Propagation characteristics of microwave optical links

    Publication Year: 1952 , Page(s): 31 - 36
    Cited by:  Papers (1)
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    The performance of point-to-point microwave links is affected considerably by the nature of the terrain which the links traverse and the variable refractivity of the lower atmosphere due to changes in the local meteorological conditions. While a great deal of information is available on these two factors, it is in many cases difficult to predict with any degree of assurance the reliability to be expected on a microwave link installed on a given path. It is usually advisable to mke an experimental survey of propagation char"acteristics and siting factors involved on such a path. This paper describes the reslllts of an experimental propagation survey which was made on two paths in the San Frmcisco Bay (USA) area. View full abstract»

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  • Meteorological effects on VHF propagation

    Publication Year: 1952 , Page(s): 20 - 30
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  • A criticism of the Feinstein - Carroll theory of tropospheric propagation

    Publication Year: 1952 , Page(s): 19
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    This paper was withdrawn as being non-applicable to Feinstein's paper in its present form. View full abstract»

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  • Internal reflection in the troposphere and propagation well beyond the horizon

    Publication Year: 1952 , Page(s): 19
    Cited by:  Papers (5)
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    A simple estimate of the feeble internal reflection from the normal troposphere explains remarkably well long puzzling fields well beyond the horizon throughout the VHF and microwave spectrum. Even in the absence of ducts, the continuous decrease with height of the index of refraction under gravitational influence makes the troposphere an inhomogeneous continuously stratified medium. The effective earth's radius notion allows for the refractive effect of this inhomogeneity in calculating the diffracted field beyond the horizon, but not for internal reflections. A bilinear model for the index profile of the normal atmosphere gives modes with db/mi attenuation rates in approximate agreement with the experimental one of roughly 1/7 db/mi at 50,400 and 3000 Mc. To a considerable extent, the internal reflection idea obviates the need for hypothesizing omnipresent atmospheric turbulence up to heights of several miles in the troposphere, a phenomenon once erroneously thought also to cause "angel" echoes on radars. View full abstract»

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  • The insignificance of continuous internal reflections in tropospheric propagation beyond the horizon

    Publication Year: 1952 , Page(s): 14 - 18
    Cited by:  Papers (1)
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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