Affiliation:
1. Department of Electrical and Control Systems Engineering National Institute of Technology Toyama College Toyama Japan
2. Graduate School of Engineering Kyoto University Kyoto Japan
3. Graduate School of Natural Science and Technology Kanazawa University Kakuma Ishikawa Japan
Abstract
AbstractRandom waves can be described as the sum of numerous plane waves, and stochastic processes describe their properties. Various methods have been used to widely investigate the propagation characteristics of electromagnetic waves in magnetized cold plasma based on a single‐plane wave approximation. On the other hand, the properties of random waves are difficult to analyze using these methods. Instead, a framework of the wave distribution function (WDF) should be employed. In this study, we provide an explicit expression for an integration kernel in a magnetized cold plasma used for the WDF method. We show that the kernel can be approximated in the case of ultralow frequency/very low frequency (ULF/VLF) parts of whistler‐mode waves with quasi‐parallel propagation. We also propose a method for estimating a WDF representing a directional distribution of the wave energy density based on the principle of maximum entropy using three‐component spectral matrix data of the magnetic field. Based on the insights obtained from the proposed method, we define a quantity called “sharpness,” which provides spreading of wave normal angles. The sharpness is particularly effective in showing the spread of the wave normal angles for random non‐single‐plane waves. Compared with the conventional methods which evaluate the propagation properties (such as planarity), the “sharpness” exhibited a low calculation load and can be implemented easily for onboard processing.
Funder
Japan Science and Technology Agency
Publisher
American Geophysical Union (AGU)
Subject
Electrical and Electronic Engineering,General Earth and Planetary Sciences,Condensed Matter Physics
Reference22 articles.
1. One and two direction models for VLF electromagnetic waves observed on-board Geos 1
2. Maximum likelihood estimation of the Fisher–Bingham distribution via efficient calculation of its normalizing constant
3. Study on direction finding method using wave distribution function with Gaussian distribution model;Goto Y.;Transactions of the Institute of Electronics, Information and Communication Engineers B,2001
4. Moments of von mises and fisher distributions and applications
5. Determination of ELF/VLF wave normal direction by wave distribution function method using Gaussian one and two direction model;Kasahara Y.;Antennas and Propagation,1998