© The Institution of Electrical Engineers
In the last few years a large part of the radio research at the Cavendish Laboratory has been concerned with the propagation of waves of low and very low frequency. The paper constitutes a summary of the results of the various experiments, which are described in detail in separate papers, some of which are as yet unpublished.3–10The results of various independent methods of measuring the apparent height of reflection of the waves show that waves of 16–30 kc/s are reflected as if from a sharply bounded horizontal surface situated at a height of (72 ± 3) km when the sun is overhead. The apparent height of reflection varies regularly with the angle of the sun and its variation may be summarized by an equation. The waves of frequency 30–150 kc/s appear to be reflected from a height of about 75 km at oblique incidence, but there is some evidence that they may be reflected from as much as 10 km higher at vertical incidence.The polarization of the waves at all frequencies is found to be approximately circular at steep incidence, but at oblique incidence (65 ) waves of a frequency of 16 kc/s are linearly polarized. No measurements of polarization at oblique incidence have been made on the higher frequencies.The absorption of the waves changes very rapidly with frequency—on a summer day the conversion coefficient varies from about 0.15 at 16 kc/s to 0.002 at 70 kc/s. Important differences in behaviour near sunrise are observed on all frequencies at steep incidence and oblique incidence. The effects of a sudden ionospheric disturbance on the reflected waves are discussed and interpreted as implying a decrease in the apparent height of reflection; the amplitude of the reflected wave is scarcely altered on 16 kc/s, but is much decreased on higher frequencies.Finally, the present state of the theory of reflection of very long radio waves is discussed very briefly.
References
-
-
1)
-
C.H. Smith
.
Indirect Ray Measurements on the Droitwich Transmitter.
Wireless Engineer
-
2)
-
R.N. Bracewell ,
J. Harwood ,
T.W. Straker
.
, The Ionospheric Propagation of Radio Waves of Frequency 16–65 kc/s over Short Distances.
-
3)
-
K. Weekes ,
R.D. Stuart
.
, The Ionospheric Propagation of Radio Waves of Frequency near 100 kc/s over Short Distances.
-
4)
-
Booker, H.G., Walkinshaw, W.: `Physical Society Report on Meteorological Factors in Radio Wave Propagation', 1946, p. 80.
-
5)
-
M. Ryle
.
(1952)
Proceedings of the Royal Society.
-
6)
-
K. Rawer
.
(1939)
Annalen der Physik.
-
7)
-
H.J. Round ,
T.L. Eckersley ,
K. Tremellen ,
F.C. Lunnon
.
Report on Measurements made on Signal Strength at Great Distances during 1922 and 1923 by an Expedition sent to Australia.
Journal I.E.E.
-
8)
-
T.W. Straker
.
, The Ionospheric Propagation of Radio Waves of Frequency 16 kc/s over Short Distances.
-
9)
-
Williams Caradoc
.
Low-frequency Radio-Wave Propagation by the Ionosphere, with particular reference to Long-Distance Navigation.
Proceedings I.E.E.
-
10)
-
R.N. Bracewell ,
W.G. Bain ,
T.W. Straker ,
C.H. Westcott
.
, The Ionospheric Propagation of Radio Waves of Frequency 16 kc/s over Distances of about 550 km.
-
11)
-
K. Weekes
.
Effect of a Sudden Ionospheric Disturbance on Long Radio Waves Reflected Obliquely from the Ionosphere.
Nature
-
12)
-
R. Gans
.
(1915)
Annalen der Physik.
-
13)
-
G.N. Watson
.
(1918)
Proceedings of the Royal Society.
-
14)
-
O.E.H. Rydbeck
.
On the Propagation of Radio Waves.
Transactions of the Chalmers University
-
15)
-
R. Bureau
.
Les Eruptions de la chromosphére solaire et leurs répercussions sur I'ionosphère et sur la propagation des Ondes.
L'Onde Electrique
-
16)
-
W. Jackson
.
(1935)
Proceedings of the Royal Society.
-
17)
-
E. Yokoyama ,
I. Tanimura
.
Some Long Distance Transmission Phenomena of L.F. Waves.
Report on Radio Research, Japan
-
18)
-
K. Weekes ,
R.D. Stuart
.
, The Ionospheric Propagation of Radio Waves of Frequency near 100 kc/s over Distances up to 1 000 km.
-
19)
-
J.E. Best ,
J.A. Ratcliffe ,
M.V. Wilkes
.
Experimental Investigation of Very Long Waves Reflected from the Ionosphere.
Proceedings of the Royal Society
-
20)
-
W. Voigt
.
(1915)
, Handbuch der Elektrizität und des Magnetismus.
-
21)
-
R.N. Bracewell
.
, The Ionospheric Propagation of Radio Waves of Frequency 16 kc/s over Distances of about 200 km.
-
22)
-
L. Espenchied ,
C.N. Anderson ,
A. Bailey
.
Trans-Atlantic Radio Telephone Transmission.
Proceedings of the Institute of Radio Engineers
-
23)
-
R.L. Smith-Rose
.
Radio Direction-Finding by Transmission and Reception.
Proceedings of the Institute of Radio Engineers
-
24)
-
J.N. Brown ,
J.M. Watts
.
(1950)
Journal of Geophysical Research.
-
25)
-
S. Butterworth ,
F.D. Smith
.
(1931)
Proceedings of the Physical Society.
-
26)
-
D.R. Hartree
.
(1931)
Proceedings of the Royal Society.
-
27)
-
E.T.S. Walton
.
(1929)
Proceedings of the Cambridge Philosophical Society.
-
28)
-
F.F. Gardner
.
The Use of Atmospherics to Study the Propagation of Very Long Radio Waves.
Philosophical Magazine
-
29)
-
J.P. Stanley
.
(1950)
Journal of Atmospheric and Terrestrial Physics.
-
30)
-
K. Weekes
.
The Ground Interference Pattern of Very-Low-Frequency Waves.
Proceedings I.E.E.
-
31)
-
A.H. Waynick
.
(1950)
, Mixed Commission on the Ionosphere.
-
32)
-
M.V. Welkes
.
(1940)
Proceedings of the Royal Society.
-
33)
-
E. Yokoyama ,
S. Namba
.
(1932)
Reports of Radio Research in Japan.
-
34)
-
O.E.H. Rydbeck
.
On the Propagation of Waves in an Inhomogeneous Medium.
Transactions of the Chalmers University
-
35)
-
R.A. Helliwell
.
Ionospheric Virtual Height Measurements at 100 kc/s.
Proceedings of the Institute of Radio Engineers
-
36)
-
C.E. Wynn-Williams
.
(1931)
Proceedings of the Royal Society.
-
37)
-
J. Hollingworth
.
The Propagation of Radio Waves.
Journal I.E.E.
-
38)
-
P.A. de Mars ,
G.W. Kenrick ,
G.W. Pickard
.
Low Frequency Radio Transmission.
Proceedings of the Institute of Radio Engineers
-
39)
-
M.V. Wilkes
.
Proceedings of the Royal Society.
-
40)
-
R. Naismith
.
Short-Distance Observations on Long-Wave Phenomena.
Journal I.E.E.
-
41)
-
R. Mesny
.
Variation en direction et intensité du champ électromagnétique d'une émission.
L'Onde Electrique
-
42)
-
E. Kappler
.
(1931)
Annalen der Physik.
-
43)
-
A. Bailey ,
A.E. Harper
.
Long-Wave Radio Transmission Phenomena associated with a Cessation of the Sun's Rays.
Bell System Technical Journal
-
44)
-
R.A. Helliwell
.
, Pulse Studies of the Ionosphere at Low Frequencies.
-
45)
-
H. Bremmer
.
(1949)
, Terrestrial Radio Waves.
-
46)
-
P.W.A. Bowe
.
The Spectrum of Atmospherics and the Propagation of Very Long Radio Waves.
Philosophical Magazine
-
47)
-
R.L. Smith-Rose
.
Solar Noise and Ionospheric Fading.
Nature
-
48)
-
T.L. Eckersley
.
(1932)
Proceedings of the Royal Society.
-
49)
-
S. Namba
.
Polarization Phenomena of Low-Frequency Waves.
Proceedings of the Institute of Radio Engineers
-
50)
-
K.G. Budden ,
J.A. Ratcliffe ,
M.V. Wilkes
.
Further Investigations of Very Long Waves Reflected from the Ionosphere.
Proceedings of the Royal Society
-
51)
-
B.F.J. Schonland ,
J.S. Elder ,
D.B. Hodges ,
W.E. Phillips ,
J.W. van Wyk
.
The Waveform of Atmospherics at Night.
Proceedings of the Royal Society
-
52)
-
E.V. Appleton
.
Some Notes on Wireless Methods of Investigating the Electrical Structure of the Upper Atmosphere (II).
Proceedings of the Physical Society
-
53)
-
J. Hollingworth
.
The Polarization of Radio Waves.
Proceedings of the Royal Society
-
54)
-
P.S. Epstein
.
(1930)
Proceedings of the National Academy of Sciences.
-
55)
-
R.N. Bracewell ,
T.W. Straker
.
The Study of Solar Flares by Means of Very Long Radio Waves.
Monthly Notices of the Royal Astronomical Society
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