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Radio and Electronic Engineer

Issue 4 • Date April 1973

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Displaying Results 1 - 9 of 9
  • A new deal for technicians

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (142 KB)  

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  • Theory of cylindrical antennas with lumped impedance loadings

    Page(s): 243 - 248
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    A method is presented for the analysis of a thin symmetrical cylindrical antenna with lumped impedance loadings along its length. The loadings can be resistive, inductive, capacitive, or mixed, and their physical size is assumed to be of the order of the antenna radius. The values of admittances of such structures obtained by the theory are in good agreement with available experimental results. View full abstract»

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  • The enhancement of spurious signals in non-linear frequency multipliers

    Page(s): 249 - 252
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    An inherent disadvantage of non-linear frequency multipliers when fed from a signal source containing spurious signals, is the enhancement of these signals the multiplier pass-band as a function of the degree of multiplication. An analysis showing the enhancement effect is given, and some experimental results are described. View full abstract»

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  • A method of measuring negative impedance

    Page(s): 253 - 256
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (649 KB)  

    A method of measuring the components of a negative impedance has been developed. The device considered possesses an S-type negative impedance as opposed to an N-type, the tunnel diode being an example of the latter. The method of measurement is illustrated by measurements taken on a negative impedance booster used for compensating the losses of a wire transmission line. The technique of measurement is fairly simple and the accuracy of measurement depends upon the grade of standard components used for comparison andpossibly also on the magnitudes of the negative impedance components to be measured. For values of a series positive resistance of 60¿ and a parallel circuit composed of a negative resistance of 160¿ and negative capacitance of 0.013 f¿F, measurements were possible with uncertainties not exceeding ±2.15%, ±0.75% and ±1.85% respectively using 1.0% grade capacitors and 0.1% grade decade resistors. View full abstract»

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  • On the design of equal ripple delay filters with Chebyshev stopband attenuation

    Page(s): 257 - 265
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    This paper is concerned with the design of low-pass filters, without all-pass sections, approximating to a constant group-delay in an equal ripple manner which simultaneously exhibit a Chebyshev type of stopband attenuation. A special type of equal ripple delay approximation, referred to as the constrained Chebyshev approximation, is used to derive the polynomial of odd degree in the denominator of the rational transfer functions of these filters. Then, using the procedure, described by Temes and Gyi, the imaginary axis transmission zeros are determined so that the Chebyshev stopband attenuation of the resulting filter is obtained. The steady-state and transient responses of these filters are discussed and shown to be superior when compared with those for the filters using Chebyshev delay approximants with the so-called standarderror function, especially for larger values of the maximum delay deviation. Tables are also presented enabling directdetermination of the odd-ordered approximants for minimum stopband attenuation. View full abstract»

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  • An experimental adaptive echo canceller for long distance telephone circuits

    Page(s): 267 - 278
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    A new concept of eliminating spurious echoes in long distance telephone circuits by adaptive echo cancellation has been experimentally implemented. In this paper the principles underlying the experimental device and the techniques used in their implementation are presented. Experimental results obtained from measurements in the laboratory as well as in a practical telephone system environment are reported. View full abstract»

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  • An investigation of integrated circuit destruction by noise pulses

    Page(s): 279 - 287
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    Conventional integrated circuits have a high failure rate when operated in an environment including electromechanical switching systems. This paper discusses the destruction modes for the circuits and the equivalent circuit for the noise generation system. Experimental results which support the concept of the equivalent circuit are discussed. Finally, the transient thermal characteristics of typical packaging systems are briefly discussed. View full abstract»

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