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Radio Engineers, Proceedings of the Institute of

Issue 3 • Date March 1931

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Displaying Results 1 - 25 of 30
  • [Front cover]

    Page(s): c1
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  • Institute of Radio Engineers - Forthcoming Meetings

    Page(s): c2
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  • Contents

    Page(s): i
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  • General Information

    Page(s): ii
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  • Suggestions for Contributors to the Proceedings

    Page(s): iii
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  • Institute sections

    Page(s): iv
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  • Geographical Location of Members Elected February 4, 1931

    Page(s): v - viii
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  • Applications for Membership

    Page(s): ix - x
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  • Officers and Board of Direction, 1931

    Page(s): xi
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  • E.F.W. Alexanderson

    Page(s): 322
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  • Institute news and radio notes

    Page(s): 323 - 332
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  • A Radio Method for Synchronizing Recording Apparatus

    Page(s): 333 - 340
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    A method is described for running two radio fading recorders at the same speed when it is necessary to have one of the recorders portable so that it can be moved to various distances from the other. In the work reported each of the recorder drums was propelled by a synchronous motor of the type used for clocks. Since wire connections were not practicable the portable recorder was controlled by a radio transmitter placed at the fixed station. The same 60-cycle source of power used to drive the synchronous motor at the fixed station was used to modulate the transmitter, the signal of which was received at the portable station and amplified sufficiently to drive the synchronous motor there. With the transmitter working on low power it was possible to drive the recorders at the same speed when separated by a distance of 16 km. A method is described for marking the two records simultaneously so that they can be superposed. View full abstract»

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  • European Aviation Radio

    Page(s): 341 - 350
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    The author summarizes observations made on an inspection trip over the major European airways. Aviation radio in Europe differs from aviation radio in the United States in the prevalent use of intermediate frequencies exclusively. European aviation radio may be divided into three major classifications as follows: (1) Communications from ground to plane and plane to ground. (2) Point-to-point communications in connection with the traffic dispatching of aircraft. (3) Meteorological communications relating to safe flying conditions. The type of equipment used for receiving and transmitting on ground and on aircraft, together with the frequencies and power used, is described. The present system of direction finding is given in detail. The use of high frequencies for aviation radio in Europe is still in a highly experimental stage. View full abstract»

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  • Discussion

    Page(s): 351 - 352
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  • Note on the Fifteen-Month Period in Solar Activity, Terrestrial Magnetism, and Radio Reception

    Page(s): 353 - 355
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    A marked 15-month period has been found in sun spots, terrestrial magnetism, and radio reception. Early in 1929 this cycle abruptly changed phase by about 60 deg., 210 deg., and 160 deg., respectively, for these elements, resulting in changed relations between solar activity and the two geophysical measures. View full abstract»

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  • Ten Years of Broadcasting

    Page(s): 356 - 376
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    The salient points in the development of broadcasting during the last decade are reviewed. It is shown that further improvement may be expected with the more extensive introduction of higher powered transmitters. View full abstract»

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  • Measurement of Power and Efficiency of Radio Transmitting Apparatus

    Page(s): 377 - 400
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    This paper reports the various methods and results of the measurement of power and efficiency in radio transmitting apparatus. High-frequency power measurements are classified as wattmeter, ammeter, calorimeter and indirect methods. The high-frequency wattmeter method and the methods based on the current and resistance measurements are briefly discussed. The direct and indirect calorimeter methods are upheld by the authors on account of their advantages, which are enumerated. The experimental results employing calorimeter methods for direct and indirect power measurement are quantitatively reported and the degree of precision obtainable in practical applications is shown. View full abstract»

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  • A New Method of Testing for Distortion in Audio-Frequency Amplifiers

    Page(s): 401 - 415
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    A periodic voltage wave consisting of a series of straight lines is distorted into a series of curves when it passes through an amplifier which gives nonuniform amplification. As such distortion can very readily be detected visually with an oscillograph, it affords a means of testing for uniformity of amplification. Mathematical analysis shows that a "saw-tooth" voltage wave is distorted into a series of exponential curves in passing through a resistance-capacity-coupled amplifier, the distortion being considerable at low audio frequencies if the coupling capacity or the grid-leak resistance is too small. The analysis proves that a falling off in amplification of less than 1/2 per cent at low audio frequencies can be detected with ease. In other types of amplifiers the distortion is not necessarily exponential, but curvature of the output wave is in general a sign of nonuniform amplification or phase shift. The method is applicable to the testing of any type of coupling circuit. The apparatus required for this method of testing is very readily constructed and is of general laboratory usefulness. View full abstract»

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  • A Rapid Method of Estimating the Signal-to-Noise Ratio of a High Gain Receiver

    Page(s): 416 - 420
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    It is shown that a figure of merit for the signal-to-noise ratio in a receiving system is obtained directly by noting how much the total noise output increases when the input circuit is tuned through resonance, in the absence of signal. The effect of mismatching the antenna and input circuit impedances is discussed, and it is concluded that although a small improvement may be obtained in certain ideal cases by making the circuit impedance much higher than the antenna impedance, other considerations indicate that the matched impedance condition gives the best results in practice. View full abstract»

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  • Oscillation in Tuned Radio-Frequency Amplifiers

    Page(s): 421 - 437
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    The wide use of screen-grid tubes renders an understanding of the conditions for stability of tuned radio-frequency amplifiers important. In this paper the relation between the feed-back capacity and the other circuit and tube parameters at the threshold of instability is computed for one, two, three, and four stages. The form of the relation is found to be Ag2 CO = w) gm where g is the conductance of the load circuit and plate resistance in parallel, assuming that all circuits are similar. The values of A are 2.0, 1.0, 0.764, and 0.667, respectively, for one, two, three, and four stages. It is found that the circuits are tuned so that the phase angle of each is approximately 45 deg. lagging, still including the plate resistance of the tube in the tuned circuit. An experimental verification of the conditions for stability of a one-stage amplifier is described. The experimental value checks the theoretical value within the accuracy of the measurements. View full abstract»

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  • The Design of Radio-Frequency Signal Generators

    Page(s): 438 - 451
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    Certain factors involved in designing signal generators free from stray voltage errors are considered. The importance of accounting for all circuit details, particularly of wiring elements, is stressed. The impedances of certain connections, particularly of the output connections from generator to measured receiver, are shown to be important. Shielding is considered in some detail. View full abstract»

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  • Measurement of Resistance and Impedances at High Frequencies

    Page(s): 452 - 460
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    It is well known that the resistance of a conductor increases with frequency. At very high frequencies the usual method of measurement fail, especially if the unknown resistance is more than about one hundred ohms. In the following it is shown that the absolute value of the unknown impedance, when put across the end of a transmission line, is a simple function of the ratio of the currents, measured at the beginning and the end of a transmission line. This method has been tested out at a wavelength of 21.8 meters, measuring the resistance of a number of grid leaks and of a decade box. The a-c resistance was considerably higher than the labeled d-c value. At the same time, the shunted capacity across the resistors has been measured and valutes have been obtained, which agree with expectations. In general, this method lends itself to measurement of impedances of any kind; but it only gives the absolute value of the unknown impedance. However, by means of a known capacity or resistance, connected in series or in parallel with the impedance to be determined, the phase of the latter and, therefore, its real and imaginary components are found. At frequencies corresponding to wavelengths longer than 100 meters the line becomes rather long. In this case another method, as described in the second part of this paper, can be applied. View full abstract»

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  • Calculation of electric and magnetic field strengths of any oscillating straight conductors

    Page(s): 461 - 466
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    There are two methods for the calculation of the electric and magnetic field strengths in any straight oscillators such as antennas and antenna systems. One method depends on the fact that the fields produced by the individual elements in the arrangement, are superposed according to their amplitudes and phases. The fields of the elements thus are produced by Hertzian dipoles. The other method depends on the formation of Hertzian vectors for the given arrangement, and the derivation of the components of the electric and magnetic fields in the usual manner. The electric field of a Hertzian dipole can be divided into three parts, designated as the near-by field, the transition field, and the remote field. The magnetic field of a Hertzian dipole is divided in two parts, a near-by field, and a remote field. On using the first method, the component fields, corresponding to the magnetic and electric field, can be represented as the sum of integrals that are determined by the arrangement of the elements on the given conductors, that is, by the current distribution along the conductor. In general, this integration cannot be completed. Using the second method, as shown in the following, we start out in a general way to give complete expressions for the electric and magnetic fields of any oscillating straight conductors. We shall now form the Hertzian vectors for such arrangements. For this also we obtain a complete representation. The expressions that have been derived here make possible simple calculation of the radiation conditions near the conductor. This is of practical importance in the calculation of radiation characteristics and radiation resistances of any linear antenna arrangements. View full abstract»

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  • Resonant Impedance and Effective Series Resistance of High-Frequency Parallel Resonant Circuits

    Page(s): 467 - 478
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    The writer has already published in a previous issue of the PROCEEDINGS a new method of measuring resonant impedance and radio-frequency resistance as applied to broadcast frequencies. In the present paper he gives, as another example of its application, some results obtained from the measurement in a band of high frequencies extending from 6300 to 26,300 kilocycles. It is ascertained that the additional dielectric loss, which is introduced into the resonant circuit by using a screen-grid tube as a dynatron, exercises only a slight influence on the measurement. The constants of the resonant circuit alone may be derived from those of the circuit combined with the tube, which can be measured directly. The correctness of the result is varified by the aid of a known value of the additional series resistance. Finally some remarks on short-wave amplification are given as a result of measurements. View full abstract»

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  • Some Details Relating to the Propagation of Very Short Waves

    Page(s): 479 - 488
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    The laws governing propagation of very short waves are the same as those governing the propagation of luminous vibrations. However, because of the difference in frequencies, the absorption, due in large measure to diffusion by particles suspended in air, is less for very short waves than for light, which explains the very great distance traveled by these waves. Communications have been carried on by very short waves between points not in direct line of vision. The phenomena of atmospheric refraction may explain this result, and the hypothesis seems to be justified by certain observations. View full abstract»

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Aims & Scope

This Periodical ceased production in 1938. The current retitled publication is Proceedings of the IEEE.

Full Aims & Scope