Transequatorial Anomalies Caused by Geomagnetic Field for East-West Propagation of VLF Radio Waves(18.6 kHz)

Kiyohide BABA

Transequatorial Anomalies Caused by Geomagnetic Field for East-West Propagation of VLF Radio Waves(18.6 kHz)

Kiyohide BABA

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A numerical analysis was made of anomalous modal interference patterns of the sunrise VLF signals as observed on transequatorial east-west paths. The Earth-ionosphere waveguide modal propagation parameters were obtained below an anisotropic inhomogeneous ionosphere with the realistic earth's magnetic field and an exponential electron density profile at a frequency of 18.6 kHz. Numerical estimation of the mode conversion coefficients of day modes to night modes was also made for some sunrise terminator model. Dominantly propagating modes which produced modal interference effects in a nighttime waveguide were identified from the efficiency of the generation of nighttime modes by the first day mode in passing through the terminator. Large reduction in the mode conversion ratio of the two dominantly propagating modes at night within the equatorial region was caused by the reduction in the efficiency of the conversion of day mode 1 into dominantly propagating lower night mode on account of a change in mode character along the path. Anomalous increase in the interference spacing near the magnetic equator was obtained numerically using some exponential profiles although its maximum value was two times as large as that obtained experimentally.

Publication: IEICE TRANSACTIONS on Communications Vol.E74-B No.2 pp.309-316

Publication Date: 1991/02/25

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Type of Manuscript: PAPER

Category: Antennas and Propagation

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Kiyohide BABA

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Kiyohide BABA, "Transequatorial Anomalies Caused by Geomagnetic Field for East-West Propagation of VLF Radio Waves(18.6 kHz)" in IEICE TRANSACTIONS on Communications, vol. E74-B, no. 2, pp. 309-316, February 1991, doi: .
Abstract: A numerical analysis was made of anomalous modal interference patterns of the sunrise VLF signals as observed on transequatorial east-west paths. The Earth-ionosphere waveguide modal propagation parameters were obtained below an anisotropic inhomogeneous ionosphere with the realistic earth's magnetic field and an exponential electron density profile at a frequency of 18.6 kHz. Numerical estimation of the mode conversion coefficients of day modes to night modes was also made for some sunrise terminator model. Dominantly propagating modes which produced modal interference effects in a nighttime waveguide were identified from the efficiency of the generation of nighttime modes by the first day mode in passing through the terminator. Large reduction in the mode conversion ratio of the two dominantly propagating modes at night within the equatorial region was caused by the reduction in the efficiency of the conversion of day mode 1 into dominantly propagating lower night mode on account of a change in mode character along the path. Anomalous increase in the interference spacing near the magnetic equator was obtained numerically using some exponential profiles although its maximum value was two times as large as that obtained experimentally.
URL: https://global.ieice.org/en_transactions/communications/10.1587/e74-b_2_309/_p

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@ARTICLE{e74-b_2_309,
author={Kiyohide BABA, },
journal={IEICE TRANSACTIONS on Communications},
title={Transequatorial Anomalies Caused by Geomagnetic Field for East-West Propagation of VLF Radio Waves(18.6 kHz)},
year={1991},
volume={E74-B},
number={2},
pages={309-316},
abstract={A numerical analysis was made of anomalous modal interference patterns of the sunrise VLF signals as observed on transequatorial east-west paths. The Earth-ionosphere waveguide modal propagation parameters were obtained below an anisotropic inhomogeneous ionosphere with the realistic earth's magnetic field and an exponential electron density profile at a frequency of 18.6 kHz. Numerical estimation of the mode conversion coefficients of day modes to night modes was also made for some sunrise terminator model. Dominantly propagating modes which produced modal interference effects in a nighttime waveguide were identified from the efficiency of the generation of nighttime modes by the first day mode in passing through the terminator. Large reduction in the mode conversion ratio of the two dominantly propagating modes at night within the equatorial region was caused by the reduction in the efficiency of the conversion of day mode 1 into dominantly propagating lower night mode on account of a change in mode character along the path. Anomalous increase in the interference spacing near the magnetic equator was obtained numerically using some exponential profiles although its maximum value was two times as large as that obtained experimentally.},
keywords={},
doi={},
ISSN={},
month={February},}

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TY - JOUR
TI - Transequatorial Anomalies Caused by Geomagnetic Field for East-West Propagation of VLF Radio Waves(18.6 kHz)
T2 - IEICE TRANSACTIONS on Communications
SP - 309
EP - 316
AU - Kiyohide BABA
PY - 1991
DO -
JO - IEICE TRANSACTIONS on Communications
SN -
VL - E74-B
IS - 2
JA - IEICE TRANSACTIONS on Communications
Y1 - February 1991
AB - A numerical analysis was made of anomalous modal interference patterns of the sunrise VLF signals as observed on transequatorial east-west paths. The Earth-ionosphere waveguide modal propagation parameters were obtained below an anisotropic inhomogeneous ionosphere with the realistic earth's magnetic field and an exponential electron density profile at a frequency of 18.6 kHz. Numerical estimation of the mode conversion coefficients of day modes to night modes was also made for some sunrise terminator model. Dominantly propagating modes which produced modal interference effects in a nighttime waveguide were identified from the efficiency of the generation of nighttime modes by the first day mode in passing through the terminator. Large reduction in the mode conversion ratio of the two dominantly propagating modes at night within the equatorial region was caused by the reduction in the efficiency of the conversion of day mode 1 into dominantly propagating lower night mode on account of a change in mode character along the path. Anomalous increase in the interference spacing near the magnetic equator was obtained numerically using some exponential profiles although its maximum value was two times as large as that obtained experimentally.
ER -