scholarly journals The Interpretation of Some Observations of Radio Waves Scattered from the Lower Ionosphere

1973 ◽  
Vol 26 (6) ◽  
pp. 815 ◽  
Author(s):  
RA Vincent
Keyword(s):  
Angular Distribution ◽  
Radio Wave ◽  
Wave Field ◽  
Spatial Scales ◽  
Lower Ionosphere ◽  
Axial Ratio ◽  
Radio Waves ◽  
Ground Pattern ◽  
Back Scattering ◽  
Distribution Of Power

Possible shapes and spatial scales of ionospheric irregularities in the lower ionosphere have been determined from analyses of two sets of radio wave back-scattering observations: measurements of the spatial scale of the ground pattern of the wave field back-scattered from altitudes near 95 km and measurements of the amount and angular distribution of power back-scattered from solitary horizontally-moving irregularities at altitudes near 75 km. At 95 km the irregularities are anisotropic, with larger horizontal than vertical dimensions. For an assumed Gaussian distribution of ionization, the inferred axial ratio (horizontal to vertical) is about three. It is tentatively concluded that the irregularities at 75 km are sharply bounded and are some kilometres in horizontal extent.

scholarly journals Perspective Ground-based Method for Diagnostics of the Lower Ionosphere and the Neutral Atmosphere

2013 ◽  
Vol 22 (1) ◽  
Author(s):  
N. V. Bakhmetieva ◽  
G. I. Grigoriev ◽  
A. V. Tolmacheva
Keyword(s):  
Radio Wave ◽  
High Power ◽  
Relative Concentration ◽  
Spectral Characteristics ◽  
Lower Ionosphere ◽  
Internal Gravity Waves ◽  
Spatial Period ◽  
Neutral Atmosphere ◽  
Radio Waves ◽  
D Region

AbstractWe present a new perspective ground-based method for diagnostics of the ionosphere and atmosphere parameters. The method uses one of the numerous physical phenomena observed in the ionosphere illuminated by high-power radio waves. It is a generation of the artificial periodic irregularities (APIs) in the ionospheric plasma. The APIs were found while studying the effects of ionospheric high-power HF modification. It was established that the APIs are formed by a standing wave that occurs due to interference between the upwardly radiated radio wave and its reflection off the ionosphere. The API studies are based upon observation of the Bragg backscatter of the pulsed probe radio wave from the artificial periodic structure. Bragg backscatter occurs if the spatial period of the irregularities is equal to half a wavelength of the probe signal. The API techniques makes it possible to obtain the following information: the profiles of electron density from the lower D-region up to the maximum of the F-layer; the irregular structure of the ionosphere including split of the regular E-layer, the sporadic layers; the vertical velocities in the D- and E-regions of the ionosphere; the turbulent velocities, turbulent diffusion coefficients and the turbopause altitude; the neutral temperatures and densities at the E-region altitudes; the parameters of the internal gravity waves and their spectral characteristics; the relative concentration of negative oxygen ions in the D-region. Some new results obtained by the API technique are discussed.

Theory of the limiting polarization of radio waves emerging obliquely from the ionosphere

1971 ◽  
Vol 324 (1558) ◽  
pp. 369-390 ◽  
Keyword(s):  
Wave Propagation ◽  
Radio Wave ◽  
Free Space ◽  
Wave Solution ◽  
Oblique Incidence ◽  
Integration Method ◽  
Lower Ionosphere ◽  
Numerical Integration Method ◽  
Radio Waves ◽  
Full Wave

The polarization of a downgoing radio wave when it has emerged from the ionosphere into free space is called the ‘limiting polarization’. To calculate it for waves at oblique incidence and medium frequencies, a full wave solution of the electromagnetic equations governing radio wave propagation in an inhomogeneous anisotropic ionized medium is used. The numerical integration method and the appropriate boundary conditions are described and some results for typical ionospheric distributions are given. The underlying problem of wave coupling is briefly discussed and the concept of complex limiting height introduced to describe the position and thickness of the region in the lower ionosphere in which the limiting polarization is established.

The use of a large-aperture radio system for meteor studies

1980 ◽  
Vol 58 (6) ◽  
pp. 779-787 ◽  
Author(s):  
R. W. Herring ◽  
P. A. Forsyth
Keyword(s):  
Radio Wave ◽  
Wave Field ◽  
Scattered Radiation ◽  
Radio Waves ◽  
Aperture Antenna ◽  
Frequency Range ◽  
Radio System ◽  
Decay Times ◽  
Simultaneous Existence ◽  
Meteor Trails

A large sampled-aperture antenna array has been used to investigate the structure of the radio wave field scattered by meteor trails. The experiment measured the phase and amplitude of the radio waves in the frequency range 20 to 30 MHz at 58 points distributed over an aperture of almost 1.2 km. The temporal changes in the structure of the scattered radiation clearly show the influence of distortion of the meteor trails by atmospheric winds, but are incompatible with the widely accepted model which attributes fading and anomalous decay times to the distortion of a single trail. The observations seem to imply the simultaneous existence of two or more trails but whether these trails are due to fragmentation of the meteoroid in the atmosphere or to simultaneous entry of independent meteoroids is not clear.

Ensemble estimation of polarization ellipse parameters

2007 ◽  
Vol 463 (2088) ◽  
pp. 3375-3394 ◽  
Author(s):  
A.T Walden ◽  
T Medkour
Keyword(s):  
Angular Distribution ◽  
Standard Deviation ◽  
Aspect Ratio ◽  
Plane Wave ◽  
Wave Field ◽  
Covariance Matrix ◽  
Time Instant ◽  
Azimuth Angle ◽  
Ensemble Estimation ◽  
Plane Wave Field

An ellipse describes the polarized part of a partially polarized quasi-monochromatic plane wave field. Its azimuth angle and aspect ratio are functions of the elements of the covariance matrix associated with the polarized part at a particular time instant. Given an ensemble of K independent samples at that time, the distributions of the estimators of these parameters are derived. The estimation is thus based on a sample ensemble at any time, and does not assume temporal stationarity. Additionally, the azimuth angle estimator has an angular distribution so that non-standard statistical methods are needed when deriving its mean and standard deviation.

scholarly journals Sensing Framework for the Internet of Actors in the Value Co-Creation Process with a Beacon-Attachable Indoor Positioning System

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 83
Author(s):  
Keiichi Zempo ◽  
Taiga Arai ◽  
Takuya Aoki ◽  
Yukihiko Okada
Keyword(s):  
Radio Wave ◽  
Indoor Positioning ◽  
Measurement Range ◽  
Pulse Interval ◽  
Retail Stores ◽  
Positioning System ◽  
Radio Waves ◽  
Positioning Systems ◽  
Environment Recognition ◽  
Indoor Positioning System

To evaluate and improve the value of a service, it is important to measure not only the outcomes, but also the process of the service. Value co-creation (VCC) is not limited to outcomes, especially in interpersonal services based on interactions between actors. In this paper, a sensing framework for a VCC process in retail stores is proposed by improving an environment recognition based indoor positioning system with high positioning performance in a metal shelf environment. The conventional indoor positioning systems use radio waves; therefore, errors are caused by reflection, absorption, and interference from metal shelves. An improvement in positioning performance was achieved in the proposed method by using an IR (infrared) slit and IR light, which avoids such errors. The system was designed to recognize many and unspecified people based on the environment recognition method that the receivers had installed, in the service environment. In addition, sensor networking was also conducted by adding a function to transmit payload and identification simultaneously to the beacons that were attached to positioning objects. The effectiveness of the proposed method was verified by installing it not only in an experimental environment with ideal conditions, but posteriorly, the system was tested in real conditions, in a retail store. In our experimental setup, in a comparison with equal element numbers, positioning identification was possible within an error of 96.2 mm in a static environment in contrast to the radio wave based method where an average positioning error of approximately 648 mm was measured using the radio wave based method (Bluetooth low-energy fingerprinting technique). Moreover, when multiple beacons were used simultaneously in our system within the measurement range of one receiver, the appropriate setting of the pulse interval and jitter rate was implemented by simulation. Additionally, it was confirmed that, in a real scenario, it is possible to measure the changes in movement and positional relationships between people. This result shows the feasibility of measuring and evaluating the VCC process in retail stores, although it was difficult to measure the interaction between actors.

Changing ionization of the lower ionosphere due to high-power radio waves

1977 ◽  
Vol 20 (12) ◽  
pp. 1230-1239 ◽  
Author(s):  
A. V. Gurevich ◽  
G. M. Milikh ◽  
I. S. Shlyuger
Keyword(s):  
High Power ◽  
Lower Ionosphere ◽  
Radio Waves
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