Method for predicting change of very-low-frequency electric wave field intensity along with time at high precision

A time-varying, very low frequency technology, applied in the field of computational electromagnetism, which can solve the problem that the field strength of very low frequency radio waves cannot be accurately predicted with time.

Pending Publication Date: 2022-04-26
XIAN UNIV OF TECH
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Problems solved by technology

[0006] The purpose of the present invention is to provide a high-precision method for predicting the change of VLF field stre

Method used

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  • Method for predicting change of very-low-frequency electric wave field intensity along with time at high precision
  • Method for predicting change of very-low-frequency electric wave field intensity along with time at high precision
  • Method for predicting change of very-low-frequency electric wave field intensity along with time at high precision

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Embodiment

[0187] In order to check the correctness and high efficiency of the present invention, based on the waveguide mode theory, the IRI model is used to invert the index model parameters, and the daily variation law of the field strength at the receiving point on the VTX-Gwalior propagation path is calculated and compared with the measured data .

[0188] The calculation parameters are set as follows: the ionosphere uses a modified exponential model, the ionosphere is an isotropic ionosphere layered horizontally from 0 to 150 km, and the layer thickness of the ionosphere is 100 meters. The transmitting point is the very low frequency transmitting station VTX in India, whose geographical coordinates are 08°26' north latitude, 77°44' east longitude, and the receiver is located in Gwalior, India, whose geographical coordinates are 26°14' north latitude, 78°10' east longitude. The transmitting frequency is f=18.2kHz, and the great circle distance between the receiving point and the tra...

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Abstract

The invention discloses a method for predicting change of very-low-frequency electric wave field intensity along with time in a high-precision mode. The method comprises the following steps that 1, ionosphere electron density Ne changing along with height is obtained in combination with an IRI model; step 2, obtaining an ionosphere reference height H and a gradient coefficient beta of the index model at each moment through the ionosphere electron density Ne; 3, deducing an electric field component Er of the very-low-frequency electromagnetic wave; 4, solving the complex dielectric constant of the ionized layer through the reference height H and the gradient coefficient beta of the ionized layer of the index model at each moment, and obtaining the reflection coefficient and the surface impedance of the ionized layer; and step 5, through the surface impedance and the electric field component Er, obtaining the field intensity of the very-low-frequency electric wave corresponding to different time periods, and accurately predicting the change condition of the field intensity of the very-low-frequency electric wave along with time. According to the method, index model parameters are inversed based on an IRI model, ionosphere reference height and gradient coefficients changing along with time are obtained, and on the basis of a waveguide mode theory, propagation characteristics of very-low-frequency electric wave field intensity changing along with time are analyzed and predicted.

Description

technical field [0001] The invention belongs to the technical field of computational electromagnetism, and relates to a method for predicting the time-varying change of very low frequency electric wave field strength with high precision. Background technique [0002] According to the division of the radio wave frequency band by the International Telecommunication Union (IUT), radio waves in the 3kHz-30kHz frequency range are called Very Low Frequency (VLF) electromagnetic waves, and their corresponding wavelengths are 10km-100km, which is The very characteristic frequency band in the radio frequency spectrum has very obvious characteristics in the propagation during the application process. In this frequency band, when radio waves with longer wavelengths are transmitted along the surface of the earth, the propagation attenuation of the signal is small, and the propagation characteristics are stable. It can be propagated around the world, and at the same time, it can penetrat...

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Application Information

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IPC IPC(8): G01V3/38
CPCG01V3/38
Inventor 蒲玉蓉吕婷席晓莉
Owner XIAN UNIV OF TECH
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