<i>Radio Ray Propagation in the Ionosphere</i>

Kelso, John M.; Hagger, H. J.

doi:10.1063/1.3047351

Cited by 86 publications

(97 citation statements)

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“…The ray connecting PT to P, through this ionosphere is found by numerical integration of the spherical coordinate ray equation (Kelso, 1964): The phase structure function appearing in the numerator can be expanded and, assuming that the phase autocorrelation function exists and that the statistics of the medium are homogeneous, we find…”

Section: Lomentioning

confidence: 99%

Effects of Strong Scattering on Transionospheric Propagation

Sprague¹

1989

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A JAN12 1990Appro~d for pUbic releas; Cstrbtln is wianited. Approved for public release; distribution is unlimited. 01 12 072 NAVAL OCEAN SYSTEMS CENTER ABSTRACT PWl&mn 200 w ds). .This report presents preliminary results of an effort to model the effects of ionospheric electron density irregularities on transionospheric propagation. The focus of the report is on propagation at HF and low VHF, where strong multiple scattering is often encountered. A strong scattering model is therefore used to predict the effects on such parameters as the phase autocorrelation function, the spectrum of intensity fluctuations, and the fluctuation in angle of arrival. Reqrements for improvements in the model and directions for later work are discussed. PREFACEThis report presents the results of modeling the effects of electron density irregularities on transionospheric propagation. The objective of this effort has been to provide a tool for determining, in real time, the expected effects of such irregularities on the performance of a given transionospheric monitoring system. While these effects can take several forms, we concentrate here on the -ariation in the phase of the signal due to scattering caused by such irregularities.In this report, we shall be mainly interested in remote locating systems. Such systems rely on accurate measurements of the phase difference between separated receive antennas to provide estimates of apparent angular location (azimuth/ elevation). Fluctuations in this phase difference due to scattering caused by electron density irregularities result in a consequent fluctuation in the apparent location of the transmitter. System performance can be seriously degraded if the correlation in the phase fluctuation between antennas is low or the mean square fluctuation in phase is large. In any case, the accurate determination of the phase fluctuations provides an estimate of the error for a given location estimate and thus provides important information for the system user.Another feature that must be addressed under strong multiple-scattering conditions is the reduction of correlation in the intensity of the signal. Under such scattering conditions, defocusing by large scale* irregularities can cause deep small-period fades in signal strength. For sufficiently strong scattering, these signal fades may have a spatial extent on the order of the size of the locating system (tens of meters). This loss of signal makes the system unreliable at best and, in some cases, inoperable.This area of investigation is not completely new; there exists a large body of related work. What is different about this effort is the extension to low VHF and HF operational frequencies. Previous work has, for the most part, dealt with higher frequencies where, in general, the relatively simple single-scatter models are applicable. Also, at these frequencies, one can generally ignore the refractive effects of the background ionization. This simplifies the implementation of the models considerably.At lower frequencies, strong multiple refra...

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Section: Lomentioning

confidence: 99%

Effects of Strong Scattering on Transionospheric Propagation

Sprague¹

1989

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“…An additional calculation of the maximum height in the layer, Zr, reached by this ray will give the precise position (point E in Fig. 6) in the layer for the maximum vertical excursion of the ray The equations used in the foregoing discussion in this subsection are given by Kelso (1964). The path in the layer (HDEJ in Fig.…”

Section: (C) Specular Reflection From Columns Of Enhanced Ionizationmentioning

confidence: 99%

“…It is assumed that between the upper and lower boundaries of each block the electron density varies linearly. Because of this assumption, by using equations given by Kelso (1964) for propagation in a linear layer (see Subsection (c) above) it has been possible to calculate for each block the position and direction of travel for radiation leaving the block. Calculations made from block to block eventually gave the angle between the direction of travel of the radiation and the field-aligned ionization contour that can be expected to reflect the radiation for perpendicular incidence_ Trial and error methods were used until an initial ray-path direction was found which terminated perpendicular to this electron density contour.…”

Section: (E) Kinking Of Contour8 Of Equal Electron Den8ity In the F2 mentioning

confidence: 99%

The Nature of Spread?F Irregularities in Antarctica

Bowman¹

1968

Aust. J. Phys.

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Some characteristics of spread.F ionograms from the Antarctic region are discussed. Very disturbed periods, such as when magnetic storms are in progress, have been neglected in this analysis. Two important characteristics are the frequent occurrence of resolved as well as diffuse traces, and the appearance from time to time of an enhanced trace which seems to be produced by signals that arrive from directions close to the magnetic field direction. Two independent sets of spread�F traces are reported. Several possible models are examined and some ray tracing performed. The analysis favours a model that incorporates kinking of the contours of equal ionization density to produce "wavelengths" in the ionospheric structure of some tens of kilometres. Because of the similarities at mid and high latitude regions, it is suggested that similar mechanisms are operating at both regions to produce spread-F

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“…[4] On the complex polarization ratio (R) plane, the contours of constant axial ratio are circles [e.g., Booker et al, 1951;Kelso, 1964], and the loci of the polarization as RADIO SCIENCE, VOL. 38, NO.…”

Section: Introductionmentioning

confidence: 99%

“…[3] The polarization locus of an electromagnetic wave is in general an ellipse, which can be characterized by the axial ratio, tilt angle and sense of rotation [Kelso, 1964; Institute of Electrical and Electronics Engineers (IEEE), 1983; Mott, 1992]. The axial ratio of a perfect CP wave is equal to one.…”

Section: Introductionmentioning

confidence: 99%

A study of the transformation bandwidth and the thickness sensitivity of the anisotropic‐slab LP to CP polarizer with several media

Huang

Lin

2003

Radio Science

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[1] In this paper, we investigate the transformation bandwidth and the thickness sensitivity of the anisotropic-slab linearly polarized (LP) to circularly polarized (CP) polarizer. The effect is represented graphically on the complex polarization ratio plane. We define a transformation bandwidth and the thickness sensitivity by using a specified axial ratio, e.g., 3 dB, as a basis. It is shown that the polarization locus for a given axial ratio leads to a circle in the polarization state diagram. When combined with the graphical description of the change in the polarization state, the transformation bandwidth and the thickness sensitivity from an initial LP wave to a desired CP wave can be obtained easily. Under the small reflection approximation, i.e., only the forward waves are considered, this method can be applied to the design of the anisotropic-slab LP to CP polarizer. This method eliminates the lengthy derivation and gives deeper physical insight to the problem. The transformation bandwidths for the anisotropic-slab polarizer with a lossless and nondispersive biaxial medium are studied. The thickness sensitivities for the anisotropicslab polarizer with several lossless media are also investigated. The results are discussed and illustrated.INDEX TERMS: 6934 Radio Science: Ionospheric propagation (2487); 6964 Radio Science: Radio wave propagation; 0689 Electromagnetics: Wave propagation (4275); KEYWORDS: anisotropic slab, polarizer, transformation bandwidth, thickness sensitivity Citation: Huang, Y. C., and K. H. Lin, A study of the transformation bandwidth and the thickness sensitivity of the anisotropic-slab LP to CP polarizer with several media,

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Radio Ray Propagation in the Ionosphere

Cited by 86 publications

References 0 publications

Effects of Strong Scattering on Transionospheric Propagation

Effects of Strong Scattering on Transionospheric Propagation

The Nature of Spread?F Irregularities in Antarctica

A study of the transformation bandwidth and the thickness sensitivity of the anisotropic‐slab LP to CP polarizer with several media

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