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Proceedings of the IRE

Issue 10 • Date Oct. 1948

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Displaying Results 1 - 25 of 29
  • Table of contents

    Page(s): 1193
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  • John A. Hutcheson, Director, 1947-1948

    Page(s): 1194
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  • The Dilemma of Specialization

    Page(s): 1195
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  • Communication by Means of Reflected Power

    Page(s): 1196 - 1204
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    Point-to-point communication, with the carrier power generated at the receiving end and the transmitter replaced by a modulated reflector, represents a transmission system which possesses new and different characteristics. Radio, light, or sound waves (essentially microwaves, infrared, and ultrasonic waves) may be used for the transmission under approximate conditions of specular reflection. The basic theory for reflected power communication is discussed with reference to conventional radar transmission, and the law of propagation is derived and compared with the propagation law for radar. A few different methods for the modulation of reflectors are described, and various laboratory and field test results discussed. A few of the civilian applications of the principle are reviewed. It is believed that the reflected-power communication method may yield one or more of the following characteristics: high directivity, automatic pin-pointing in spite of atmospheric bending, elimination of interference fading, simple voice-transmitter design without tubes and circuits and power supplies, increased security, and simplified means for identification and navigation. View full abstract»

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  • Some Notes on Noise Figures

    Page(s): 1205 - 1214
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    The subject matter of this paper first appeared in the form of laboratory reports. Outside interest in these reports prompted the preparation of the material for publication. Despite the attention given to noise and noise figures in the literature, the basic concepts are still little understood by the average engineer. This paper takes up the basic ideas and definitions proposed by H. T. Friis and presents them in a form that is more easily understood. Naturally, complete generality is not achieved, and the conclusions are subject to restrictions. Nevertheless, useful results are obtained. Subjects treated include expositions of the meaning of the "available gain," and the derivation of simple noise-figure formulas for many types of circuits in common use. View full abstract»

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  • Cosmic Static

    Page(s): 1215 - 1218
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    A brief description of the apparatus is given. The results of a survey of the galaxy made at a frequency of 480 Mc are compared to a previous survey made at 160 Mc. The principal new findings are a projection from Sagittarius in the direction of the north galactic pole; a supplementary small rise in Aquila; and a splitting of the maxima in Cygnus and Orion each into two parts. View full abstract»

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  • Comparison of Calculated and Measured Phase Difference at 3.2 Centimeters Wavelength

    Page(s): 1218 - 1223
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    Radio propagation and associated meteorological measurements, made by the Electrical Engineering Research Laboratory of the University of Texas during April, 1946, on a path from Gila Bend to Sentinel in the Arizona desert, show that, for meteorological conditions that could be represented by a linear M curve, the magnitude and phase of the field resulting from propagation over a 27-mile path on 3 cm could be calculated on the basis of a direct wave, and one reflected from a surface tangent to the actual profile at the point of reflection. Apparent reflection coefficients between 0.3 and 0.8 were found for desert sand on 3 cm for this path. View full abstract»

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  • The Chemistry of High-Speed Electrolytic Facsimile Recording

    Page(s): 1224 - 1235
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    A brief survey is made of the various electrolytic recording processes which have found use in facsimile. The requirements and conditions necessary for recording at higher speeds are discussed, with emphasis on the mechanism which has produced the most promising high-speed recording processes. Three general types of azo-color reactions which have proved most satisfactory at the higher recording speeds are described. View full abstract»

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  • Helical Beam Antennas for Wide-Band Applications

    Page(s): 1236 - 1242
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    The helical beam antenna has inherent broad-band properties. Over a wide frequency band the pattern shape, circularity of polarization, and terminal impedance are relatively stable. Measured performance data are presented for a medium-gain helical beam antenna of optimum dimensions with a bandwidth of about 1.7 to 1. A high-gain broadside array of four such helices is described. Other wide-band applications of helical beam antennas, including omnidirectional types, are also discussed. View full abstract»

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  • Antenna Design for Television and FM Reception

    Page(s): 1242 - 1248
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    An approximate method is presented herein of determining, for preliminary design, the resistance and reactance variation with frequency of an antenna or dipole with change of physical dimensions, and to indicate the essential requirements for good performance over a wide band of frequencies necessary for efficient reception of all television channels and FM bands as now allocated for public use by the Federal Communications Commission. A unique antenna system designed to be efficiently responsive over the entire frequency band from 44 to 225 Mc is described. View full abstract»

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  • A Method of Measuring the Field Strength of High-Frequency Electromagnetic Fields

    Page(s): 1249 - 1251
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    An analysis of a case of an electron beam directed parallel to a uniform steady magnetic field with a high-frequency electromagnetic field at right angles to the magnetic field results in a relation among the variables which is particularly simple, if the magnetic field is adjusted so that ess/ mc ωco wherωco is the frequency of the electromagnetic field (Gaussian units). One use of the relation mentioned is that of measuring the field strength of the high-frequency field. View full abstract»

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  • Mode Separation in Oscillators with Two Coaxial-Line Resonators

    Page(s): 1252 - 1255
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    The resonance frequencies of a capacitance-terminated coaxial-line resonator may readily be determined graphically. The graphical analysis shows clearly why separation of the various modes of resonance is possible in oscillators using two resonators. Mode separation is favored by the use of resonators that have a large difference in their products of characteristic impedance and terminating capacitance. Too great a difference in the CZ0o products may, however, result in the coincidence of two modes of resonance for certain tuning combinations. Measured tuning curves for a lighthouse-tube oscillator agree with predicted curves in their general aspects. The agreement is improved by considering the tube electrodes and leads as extensions of the coaxial lines, terminated in capacitances smaller than the lumped interelectrode capacitances. View full abstract»

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  • Contributors to Proceedings of the I.R.E.

    Page(s): 1259 - 1260
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  • Correspondence

    Page(s): 1261 - 1262
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  • Institute news and radio notes

    Page(s): 1263 - 1320
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  • Books

    Page(s): 1269 - 1273
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  • Sections

    Page(s): 1270 - 1271
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  • IRE People

    Page(s): 1274 - 1275
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  • William A. Edson, Chairman, Atlanta Section, 1948-1949 and William H. Carter, Jr. Chairman, Houston Section, 1948-1949

    Page(s): 1276
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  • Nuclear Reactions and Nuclear Energy

    Page(s): 1277 - 1282
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  • Wide-Deviation Frequency-Modulated Oscillators

    Page(s): 1282 - 1284
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    Instantaneous frequency and power relations in wide-deviation frequency-modulated oscillators are discussed with special reference to the oscillators used in particle accelerators. There are no fundamental limitations on deviation and modulating frequency in the present range of interest, but a fluctuating load effect arises which may be of importance. View full abstract»

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  • Frequency Measurement by Sliding Harmonics

    Page(s): 1285 - 1288
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    A method of measuring radio frequencies is described which uses an interpolating, or adjustable, frequency standard. Harmonics of this standard are caused to slide along the frequency scale until the one next below the frequency under measurement is brought up to match that frequency. The number of the used harmonic is readily determined from a simple calibration of the detector, heterodyne frequency meter, or receiver used to receive the frequency being measured. The positive increment in frequency of the used harmonic is determined from the control dial of the adjustable frequency standard. The use of wide-band receivers and interpolating equipment is avoided. Accuracy of measurement of the order of 10 parts per million is realized with the equipment described. If the interpolating frequency standard is treated as a highly stable heterodyne frequency meter, it may be used with many advantages in a conventional frequency-measuring system. The methods discussed are applicable to frequencies up to 1000 Mc. View full abstract»

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  • Calculation of Doubly Curved Reflectors for Shaped Beams

    Page(s): 1289 - 1296
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    A method based upon conservation of energy and the simple laws of geometrical optics is described for the calculation of double-curvature surfaces to produce from a point source a shaped beam of arbitrary shape in one plane and uniformly narrow in the perpendicular planes. A specific application of the shaped-beam antenna is in connection with radar antennas for airborne navigational systems, for which the optimum elevation pattern is found empirically to be G(0) = Kcsc20 cos 0. A reflector to produce from a given primary source the required pattern is the envelope of a family of paraboloids determined by a central-section curve which is adjusted to give the necessary distribution of energy for the shaped beam. A test for the single-valuedness of a computed surface is described. Patterns are shown for experimental antennas whose reflectors were computed by this method. It is demonstrated that some control of the antenna pattern can be achieved by proper motion of the antenna feed. A discussion of errors is included in an Appendix. View full abstract»

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Aims & Scope

This Periodical ceased production in 1962. The current retitled publication is Proceedings of the IEEE.

Full Aims & Scope