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Electrical Engineers, Proceedings of the Institution of

Issue 5 • Date May 1963

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Displaying Results 1 - 25 of 27
  • Small-signal responses realizable from d.c.-biased devices

    Publication Year: 1963 , Page(s): 823 - 829
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (849 KB)  

    It is suggested that there are realizability criteria pertaining to active as well as to passive systems. In particular, the small-signal stability properties of an active electrical network cannot be realized in practice unless the network conforms to certain limitations. Criteria are derived for small-signal immittances and afterwards extended to immittance matrices. The notion of general realizability is interpreted in terms of the physical nature of an active device. The non-linearity inherent in all active devices is assumed to `function¿ by means of a `diversion energy¿. This restricts the validity of some methods of non-linear analysis. View full abstract»

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  • Envelope stability of low-frequency transistor oscillators

    Publication Year: 1963 , Page(s): 830 - 844
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1226 KB)  

    Small departures from a constant envelope of LC oscillators using the normal self-bias circuits for stabilization may be described by a second-order linear differential equation. Besides some general conclusions, detailed results are presented for two usual emitter-base diode characteristics. More complicated bias arrangements and the modulation response are briefly considered. Large departures from equilibrium lead to a pair of non-linear differential equations. Some graphical solutions of these equations are sketched on the phase plane and lead to an understanding of the `large¿ behaviour of the envelope. It is tentatively concluded that `small¿ stability ensures `large¿ stability. An analogue computer has been used to confirm some of the theory. View full abstract»

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  • The conductivity of oxide cathodes. Part 16: Thermodynamic considerations of matrix stability

    Publication Year: 1963 , Page(s): 845 - 847
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (471 KB)  

    Under conditions of free evaporation in vacuo from a platinum substrate the sublimate from barium oxide is almost wholly oxide, whereas that from strontium oxide is a mixture containing a high proportion of metallic strontium. The present Part suggests that this difference in behaviour can be explained in terms of the energy difference between the heats of formation and sublimation of the two oxides. This hypothesis predicts that both calcium oxide and magnesium oxide should behave in a manner similar to strontium oxide, and experiments show that the prediction is correct. A further prediction suggests that barium oxide should itself behave like the other three alkaline-earth oxides if its evaporation is physically restricted, and this again turns out to be demonstrable. The hypothesis is finally used to provide a satisfactory explanation for the emission of excited strontium-metal vapour from a mixed-oxide matrix under heavy current loading. View full abstract»

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  • Over-moded rectangular waveguide for high-power transmission

    Publication Year: 1963 , Page(s): 848 - 858
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1282 KB)  

    The limitation in power-carrying capacity of standard-size rectangular waveguides due to Joule heating effects is briefly discussed. Suggestions are advanced for using a larger-sized rectangular waveguide whose transverse dimensions are just less than ¿ × 2¿. The problems that arise from over-moding are considered, with particular reference to trapped-mode resonance effects. A method of eliminating these resonances using a multiple-slot filter suitable for high power levels is suggested. Experimental results on such a system at low power levels are described. View full abstract»

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  • A variational integral for the propagation coefficient of a cylindrical waveguide with imperfectly conducting walls

    Publication Year: 1963 , Page(s): 859 - 864
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (646 KB)  

    A variational integral for the complex propagation coefficient of a cylindrical waveguide having arbitrary cross-section and imperfectly conducting walls is derived. This integral is used, in particular, to determine the nature of the modes that may be propagated in a lossy rectangular waveguide. In certain conditions these stable modes are well described as simple linear combinations of a TEmn and TMmn mode. It is proposed that such combinations be called quasi-stable modes. The variational formulation shows that the two quasi-stable modes associated with the mode numbers m, n are the linear combinations that produce, respectively, maximum and minimum values of attenuation coefficient when calculated using the power-loss method. View full abstract»

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  • Measurement of power by absorption of the angular momentum of a circularly polarized wave

    Publication Year: 1963 , Page(s): 865 - 868
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (493 KB)  

    The absorption of angular electromagnetic momentum produces a torque on the dissipative element directly proportional to the power and inversely proportional to the velocity of rotation of the field. This technique is well known at low frequencies in its application to the induction motor. Thus at 50/cs the starting torque on the rotor of such a machine, operated from a polyphase supply, is quite considerable even when the power input is small. In fact, at all frequencies up to the v.h.f. part of the spectrum, sufficient torque can be obtained in this way, at medium power levels, to give a direct reading of the power absorbed. At 200 Mc/s. for example, 50 mW will give an observable torque. With microwaves the conditions are very different, and the forces tending to rotate the absorbing termination are several orders of magnitude smaller, so that some means must be found to amplify the effect. In this paper it is proposed to develop a wattmeter for 35 Gc/s using a local oscillator and a mixer to give an output at the difference frequency, thus setting up a rotating field to operate on the absorbing termination, at a correspondingly reduced angular velocity. Some calculations are given to show what can be achieved by this method and also by direct-reading instruments in the v.h.f. band. View full abstract»

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  • Analysis of four-port circulators using non-reciprocal phase shifters and directional couplers

    Publication Year: 1963 , Page(s): 869 - 880
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1617 KB)  

    An analysis has been made of the factors affecting the performance of 4-port circulators based on non-reciprocal phase-shifter and directional-coupler networks. The effects on the adjacent-arm isolation of phase-shift error, coupling error, dissimilarities between the couplers, and non-reciprocal loss in the phase shifters are examined. The effects on the alternate-arm isolations and input matches of the isolations and matches of the couplers, and the matches of the phase shifters are then discussed. The power-handling capacity is not considered. The results of the analysis lead to the choice of a network using similar E-plane multi-branched waveguide couplers, two similar non-reciprocal phase shifters of ¿¿ differential phase shift, and one reciprocal phase shifter of ¿¿ phase lag relative to the unloaded line. Components meeting the limits derived by the analysis were developed, and used in the construction of two circulators in waveguide 14 working in the band 5.925¿6.425 Gc/s. One of these maintained over an 8% bandwidth isolations greater than 30 dB, voltage standing-wave ratios greater than or equal to 0.95 and insertion losses less than or equal to 0.3 dB. The second maintained over a 4% bandwidth isolations greater than 33 dB, and similar v.s.w.r.s and insertion losses. The development work on the phase shifters and couplers is described, and the results obtained are given. The performance of a circulator is predicted by the theory from measurements on the components, and compared with measurements on the circulator. Finally, the factors limiting the performance of the present circulators are discussed, and suggestions are made for further improvement. View full abstract»

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  • Distribution of current on cylindrical radiating dipoles

    Publication Year: 1963 , Page(s): 881 - 886
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (719 KB)  

    The distribution of current on a dipole comprising cylindrical conductors is approximately sinusoidal, but in certain problems a more accurate solution is required. A number of theoretical attempts have been made to obtain a better approximation and are in reasonable agreement. These methods are, however, laborious to apply in practice and are also limited in application. In the paper a simple method is described that enables a current distribution more accurate than the sinusoidal approximation to be determined. The method is based on the perturbation principle and, besides being applicable to a wide variety of cases, is in good agreement with more rigorous theoretical approaches and with measurements. View full abstract»

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  • Analysis of radar systems for the observation of incoherent radio-wave scattering in the ionosphere

    Publication Year: 1963 , Page(s): 887 - 896
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1284 KB)  

    The demonstration by Bowles of the radar detection of incoherent radio-wave scattering from free electrons in the ionosphere has shown the possibility of measuring from the earth's surface the electron density the upper side of the F-layer. The distribution in volume and the relative motion of the scatterers gives rise to a range-distributed and Doppler-spread echo on a radar. The choice of the best radar system for the detection of such targets is complex. The paper analyses the response of f.m. and pulse radars to volume-distributed targets, both with stationary and with relatively moving scatterers. The equipment parameters necessary to ensure the best signal/noise ratio are found for the two radar systems, and their merits are compared. The relative performance for a given range-resolution and post-detector integration is shown to depend on the ratio of maximum peak to maximum mean power for the radar transmitter. As an example, the relative performance of particular 90Mc/s f.m. and 400Mc/s pulse systems are compared. The signal/noise performance is similar, but the pulse system is shown to have advantages which render it more attractive. View full abstract»

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  • Aerials in an ionosphere of zero conductivity

    Publication Year: 1963 , Page(s): 897 - 898
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The method of electrodynamic similitude is applide to show how the impedance and effective length of some simple aerials depend on the dielectric constant of the medium in which they are placed. View full abstract»

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  • A new approach to the control of directional patterns for scanned aerial arrays and its application to multiplicative arrays

    Publication Year: 1963 , Page(s): 899 - 900
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  • Incorporation of variable-capacitance diode elements in microwave devices

    Publication Year: 1963
    Save to Project icon | PDF file iconPDF (132 KB)  
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  • More coaxial cables or waveguides for long-distance communication

    Publication Year: 1963
    Save to Project icon | PDF file iconPDF (164 KB)  
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  • Effect of rotor eccentricity on the magnetic field in the air-gap of a non-salient-pole machine

    Publication Year: 1963 , Page(s): 903 - 915
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1227 KB)  

    A method of calculation is developed for the determination of the magnetic field in the air-gap of an idealized machine without salient poles and with an eccentric rotor. The basic case of a concentric rotor is considered first, simplifying assumptions being made to render the problem amenable to calculation. The magnetic potential at any point is governed by the currents flowing in the windings and also by the magnetization induced on the cylindrical surfaces of the rotor and the stator. The potential functions appropriate to the stator, rotor and air-gap are determined for several elementary conductor arrangements, and hence the complex potential function is derived at any point in the air-gap. The eccentric annulus representing the air-gap when the rotor is displaced is related to a concentric annulus by means of a conformal transformation. Hence the complex potential is known at any point in the eccentric air-gap, and expressions are thence derived for the potential and flux functions at any point in the gap due to a single current-carrying conductor placed arbitrarily in either stator or rotor. Finally, the application of the principal results of the analysis is exemplified by the calculation of the radial magnetic field at the surface of an eccentric rotor with an arbitrary stator winding. View full abstract»

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  • Close-ratio two-speed single-winding induction motors

    Publication Year: 1963 , Page(s): 916 - 934
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2693 KB)  

    It has already been shown how an induction motor with a single winding of normal type can be made to give efficient and economic operation at two alternative speeds, using the new method of polyphase pole-amplitude modulation. Various detailed improvements in this method have been devised since it was first developed; but both the original method and the modifications hitherto disclosed are only directly applicable to pole-combinations in which neither pole-number is a multiple of three, or to multiple repetitions of such pole-combinations. The paper discusses further theoretical developments which enable the same principles to be applied for any speed and pole ratio between unity and 1.5; and it describes theory and design methods for 6/8-pole and 6/4-pole machines, as typical examples. For all speed ratios, the winding can be made of coils which are all identical, undivided and of standard type. Six control leads and six terminals only are required in every case, and the control gear is therefore extremely simple, and can be standardized for all speed ratios. The method is so general that, 70 years after its invention, the standard squirrel-cage induction motor has, in effect, ceased to be a single-speed machine, and has become a 2-speed machine at a trivial extra manufacturing cost. View full abstract»

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  • An investigation of the dynamic behaviour of the pulsed arc and its plasma in a single-anode mercury-pool valve

    Publication Year: 1963 , Page(s): 935 - 943
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1053 KB)  

    The dynamic behaviour of the pulsed arc and its plasma in an experimental single-anode mercury-pool valve with anchored cathode spot was systematically investigated with the valve in periodic operation at mains frequency with steady resistance loads, and with superimposed short-duration anode-current pulses. The principal tentative conclusions were found to be as follows: (a) A change of instantaneous value of anode current alters quantitatively the structure of the plasma column of the valve from what it would be if the valve were carrying a direct current of the same magnitude. The magnitude of the plasma changing effect is related to the rate of change of anode current in such a manner that both electron as well as ion density exhibit individually a hysteresis effect, causing the anode voltage to be higher than its steady-state value when the current increases, and lower when it decreases. (b) Shortly after the start of commutation and as the anode current falls there is first a rise of electron density before it starts to decay. This may perhaps be caused by ionization resulting from collisions of pairs of metastable excited atoms. (c) A disturbance of the plasma column by a transient increase of anode current is followed by a period of restoration during which anode voltage, plasma space voltage and electron temperature are temporarily reduced, whereas electron and ion densities are temporarily increased. The intensity of optical radiation from the plasma during some period following the disturbance bears no direct relationship to the electron and ion densities during that time. View full abstract»

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  • Electricity supply costs and tariffs. A review of progress

    Publication Year: 1963 , Page(s): 944 - 954
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1589 KB)  

    First Page of the Article
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  • Control and safety requirements for the electrical engineering design of the C.E.G.B. nuclear power stations

    Publication Year: 1963 , Page(s): 955 - 968
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1588 KB)  

    The paper some features of the operation of nuclear power stations, which are a necessary part of the British power-system requirements. The electrical engineering systems make a major contribution to successful design, exploiting first the ability of electricity to give a reliable economical power source to station auxiliaries, and secondly the techniques, largely electrical, of measuring plant parameters and their effective control. As the equipment concerned has been described in detail elsewhere, the authors feel that an appraisal of the close relation between the control functions and the safety and security of the whole of a nuclear station might be of interest. The continuing development of these features is discussed, together with the outlook evolved from experience in the design of the first C.E.G.B. stations. View full abstract»

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  • Lightning flashovers on the British grid

    Publication Year: 1963 , Page(s): 969 - 974
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (714 KB)  

    The frequency of lightning flashovers to overhead lines is calculated on certain assumptions concerning the characteristics of the leader stroke, and is shown to depend on a number of parameters such as line height, shielding angle of earth wires, tower-footing resistance and the insulation level of the line. Results are given in the form of a ratio: the number of flashovers per unit length per year to lightning strokes to earth per unit area per year. To determine absolute values of flashover frequency requires a knowledge of the rate of strokes to earth, a characteristic which is not known precisely, but the performance of different systems operating in a region of uniform lightning activity can be compared; this comparison has been made for the different transmission voltages of the British system. Lightning-fault statistics have been used to estimate the frequency of lightning strokes to earth exceeding 5kA. View full abstract»

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  • Discussion on ¿A new linear oscillating motor¿

    Publication Year: 1963 , Page(s): 975 - 976
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  • Discussion on ¿The alternating magnetic flux distribution in right-angled corners of transformer laminations¿

    Publication Year: 1963 , Page(s): 977 - 979
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  • Discussion on ¿Changing influences in the planning of the grid system¿

    Publication Year: 1963 , Page(s): 980 - 981
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  • The application of silicon controlled rectifiers to the control of electrical machines

    Publication Year: 1963
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  • The application of silicon controlled rectifiers to the control of electrical machines

    Publication Year: 1963
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  • Surface resistance of glass

    Publication Year: 1963 , Page(s): 983 - 988
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (747 KB)  

    If a direct voltage is applied between two electrodes on the same surface of a glass specimen the resultant leakage current diminishes with time. Previous literature concerning this phenomenon is reviewed and some anomalies are noted. Research work aimed at determining the nature and properties of the change is described. It is concluded that the appreciable decrease in leakage current with time is due mainly to polarization at the interface between the electrode and the surface film, and not to a change in surface resistivity of the specimen. View full abstract»

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Aims & Scope

The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

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