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Radio and Electronic Engineer

Issue 12 • Date December 1973

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Displaying Results 1 - 8 of 8
  • The engineer's pay, progress and prospects

    Page(s): 713 - 714
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (214 KB)  

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  • The computation of the best windward and running courses for sailing yachts

    Page(s): 715 - 727
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2697 KB)  

    The best course for a yachtsman to steer, for any course to windward, can be shown to be that which resolves the maximum speed in the direction of the true wind for any course lying between the reciprocal sailing vectors producing such a maximum. Outside these vectors it is nearly always quicker to steer a direct course, the exception being on the running points of sailing in light wind conditions. Unfortunately measurements of true wind bearing and speed are not possible on a moving yacht and measurements of only the apparent wind parameters, namely, apparent wind velocity and apparent wind angle ¿ less the leeway angle A, are possible. The other practical velocity measurement is the yacht's speed through the water. The parameters available for the computation of the best course are therefore two velocities and one inaccurate angle¿the inaccuracy being due to leeway. Previously postulated solutions to the problem have confessed lack of feasibility due to the leeway error and due to the cost of the computation, for instance circuits employing 105 transistors consuming 5 W of power1. This paper explains measurement methods which are free of errors due to leeway and describes an electronic computer which will enable the best sailing vector to be found and indicated on both the close-hauled and running points of sailing. The additional power required to compute the best course from the input of established instruments measuring apparent wind velocity and sailed velocity is 0¿12 W. View full abstract»

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  • The design of a precision video delay line

    Page(s): 729 - 743
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1756 KB)  

    The paper reviews briefly the very stringent conditions which must be fulfilled by video delay lines connected in a television programme chain. The most suitable method of construction is found to be a cascade of delay sections of the same image impedance, and three types, onebelieved to be novel, are examined in detail with respect to their suitability for long delays inserted in main signal-handling paths. It is concluded that the advantage lies with low-pass sections combining pairs of complex conjugate m values in an appropriate configuration. These offer a markedly improved performance compared with conventional methods of construction, together with a substantial reduction in the number of inductors for a given delay over the video band. Guide lines for the design of video delay networks are laid down, and methods of compensationfor component dissipation are discussed in some detail. The performance of a prototype 1 ¿s delay line built on these principles has fully confirmed the theoretical findings. View full abstract»

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  • Static voltages on the guy insulators of m.f. and i.f. broadcast tower antennas

    Page(s): 744 - 750
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (717 KB)  

    A new approximate method for calculating the static voltages on the guy insulators of m.f. and i.f. broadcast tower antennas is given. The method is based on an integral-equation technique, where the integral equation is solved by the so-called point matching method; the unknown charge densities are approximated by polynomials. The polynomial expansion provides very significant advantages, primarily because it leads to the integrals in closed form, and because itrequires a very low order of polynomial. A numerical example is given to illustrate the method. View full abstract»

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  • The theory of coupling in a tapered waveguide

    Page(s): 751 - 756
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    A theory is given which enables the overall coupling between two modes to be calculatedfor a tapered waveguide, if the coupling factor between the modes, the phase constants of the modes, and the characteristic impedances of the waveguide for the two modes are known at all points along the taper. It is thus restricted to those cases where a characteristic impedance can be defined, i.e. waveguides bounded by a very good conductor and not containing very lossy materials. The theory is found to be valid even if one of the modes is cut off over part of the length of the taper. `Taper¿, in the present context, includes the case of uniform dimensions and gradually varying properties of one or more of the materials contained in the guide. The overallcoupling between the H01and H02modes of a copper-walled circular-waveguide taper of raisedcosine form is calculated as an example. View full abstract»

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  • New books received

    Page(s): 769 - 770
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (186 KB)  

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