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Proceedings of the IEE - Part III: Radio and Communication Engineering

Volume 100, Issue 64, March 1953

Volumes & issues:

Volume 100, Issue 64

March 1953

Radio telemetering
Discussion on “Radio telemetering” before the Radio Section, 12th November, 1952
The authors' reply to the discussion on “Radio telemetering”
The impact of television on sound broadcasting. Radio Section discussion meeting, 27th October, 1952
The reflection and absorption of radio waves in the ionosphere
  • Author(s): W.R. Piggott
  • Source: Proceedings of the IEE - Part III: Radio and Communication Engineering, Volume 100, Issue 64, p. 61 –72
  • DOI:  10.1049/pi-3.1953.0015
  • Type: Article
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  • p. 61 –72 (12)
    A brief historical review is given of the investigations on the absorption of radio waves made in the United Kingdom since 1935 together with a detailed discussion of the factors which must be considered when making accurate measurements of this phenomenon. An outline of the theory of ionospheric absorption and its application to practical absorption measurements is included. The effects of double refraction, polarization, spatial attenuation, dispersion, ionospheric inhomogeneities and partial reflection, which modify the apparent attenuation of radio waves reflected in the ionosphere, are discussed. The methods used to minimize errors due to these factors are presented in detail. The experimental techniques used in the routine absorption measurements are described fully. The detailed results of the measurements of the absorption of radio waves in the ionosphere, conducted in South-East England during the years 1935 to 1948, are being published separately.
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The measurement of the phase velocity of ground-wave propagation at low frequencies over a land path
  • Author(s): B.G. Pressey ; G.E. Ashwell ; C.S. Fowler
  • Source: Proceedings of the IEE - Part III: Radio and Communication Engineering, Volume 100, Issue 64, p. 73 –84
  • DOI:  10.1049/pi-3.1953.0016
  • Type: Article
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  • p. 73 –84 (12)
    The paper describes the measurement of the change of phase with distance of a 127.5-kc/s wave over a particular inhomogeneous land path and the deduction of the mean velocity.The measuring system made use of transmissions from stations of the English chain of the Decca Navigator System, and the path studied was that between the Lewes (Sussex) and Warwick stations (177 km). With the aid of a mobile phase-measuring equipment the difference between the phase of the signal from one transmitter and that of the signal from the other transmitter was measured with an accuracy of 0.25° at 25 points along the path. From these results and a knowledge of the exact position of the points it was possible to plot a curve showing the deviation of the measured phase from that calculated on the assumption of a velocity equal to that in free space.The mean velocity deduced for the path was 299 230 ± 12 km/sec.An examination was made of the measured change of phase along the path in relation to the profile and geological structure. Although there was no definite evidence of the phase of the wave being affected by the ground contours, the influence of the nature of the soil was very marked. A detailed study of the geological structure was undertaken and the electrical characteristics of each section of the path were assessed. A high velocity over ground of good conductivity and a low velocity over ground of poor conductivity was clearly shown.Comparisons between the measurements and the phase changes derived by a method based on theoretical curves of phase lag over homogeneous ground showed good correlation. They also confirmed the theoretical predictions of a characteristic phase disturbance at the boundary between sections of differing conductivity. It is concluded that this method of phase determination over an inhomogeneous path is one which offers a good approximation to the phase changes actually taking place.
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Waveguide attenuation and its correlation with surface roughness
  • Author(s): F.A. Benson
  • Source: Proceedings of the IEE - Part III: Radio and Communication Engineering, Volume 100, Issue 64, p. 85 –90
  • DOI:  10.1049/pi-3.1953.0017
  • Type: Article
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  • p. 85 –90 (6)
    Measurements of the attenuation produced by air-filled drawn waveguide tubing have been made at a frequency of 9375 Mc/s. The theoretical and experimental performances of various waveguide surfaces are compared and discussed. Detailed studies of the roughness of the internal surfaces of certain standard commercial waveguides have been made, to determine the orders of magnitude of the irregularities and to try to set up a correlation between measured and calculated attenuation values. It is concluded that the discrepancies between these values are due solely to surface roughness, and it is doubtful whether further improvements in surface finish over that of present precision-drawn tubes are required for any applications at frequencies near or below 24 000 Mc/s.The effects of small changes in waveguide dimensions on attenuation, together with the problems involved in measuring both the attenuation and d.c. resistivity of a waveguide sample, are considered.
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Noise in thermionic valves
New equipment for impedance matching and measurement at very high frequencies
  • Author(s): A. Bloch ; F.J. Fisher ; G.J. Hunt
  • Source: Proceedings of the IEE - Part III: Radio and Communication Engineering, Volume 100, Issue 64, p. 93 –99
  • DOI:  10.1049/pi-3.1953.0019
  • Type: Article
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  • p. 93 –99 (7)
    The slotted transmission line has long been used as a standard device for determining impedance. Over the v.h.f. range, however, the constructional difficulties due to the physical length required for the slotted line make it primarily a laboratory instrument. The need for an alternative device of comparable or improved accuracy, capable of giving much more rapid measurements, and sufficiently robust to be used on field tests of aerial arrays, has led to a modified approach.A test section of low-loss coaxial line, which may be as short as one-third of the equivalent slotted line, is fitted with fixed probes to measure the relative voltage amplitudes at three known points. From these ratios the unknown impedance can be found, either analytically or graphically, each ratio defining a circular locus on the Smith chart. The frequency range covered by a line of this type is approximately 3:1; near mid-frequency the present equipment can measure standing-wave ratios up to 5:1, corresponding to resistive loads ranging from 15 to 375 ohms for a line of 75 ohms.An important advantage of the new equipment is that the adjustment of a load to a prescribed value is shown by the simultaneous zero reading of two meters.
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A review of present knowledge of the ionospheric propagation of very-low, low- and medium-frequency waves
  • Author(s): F.A. Kitchen ; B.G. Pressey ; K.W. Tremellen
  • Source: Proceedings of the IEE - Part III: Radio and Communication Engineering, Volume 100, Issue 64, p. 100 –108
  • DOI:  10.1049/pi-3.1953.0020
  • Type: Article
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  • p. 100 –108 (9)
    The paper deals with the ionospheric propagation of waves of frequencies less than 3 Mc/s and is confined mainly to transmission over medium and long distances (greater than 500 km).The results of investigations on low and very-low frequencies (less than 300 kc/s) are summarized under the headings of field strength, phase and polarization measurement, the effects of ionospheric disturbances, the study of local ionospheric characteristics and theoretical studies. Since our knowledge of medium-frequency propagation was adequately summarized in a report64 in 1937, only work done since that date has been considered here. An important item of the recent work is the study of ionospheric cross-modulation.The paper concludes with a summary of our present knowledge of the subject and recommendations for further studies.
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North-Eastern Radio and Measurements Group: Chairman's address. Wired broadcasting
Discussion on “Waveform computations by the time-series method”
Discussion on “The synthesis of a network to have a sine-squared impulse response”
Harmonic and intermodulation distortion in “power law” devices
A theory of time series for waveform-transmission systems
Analysis of a transmission-line type of thermionic-amplifier valve
The influence of bends and ellipticity on the attenuation and propagation characteristics of the H01 circular waveguide mode
Meetings of the Radio Section: abridged minutes

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