Showing papers on "Radio wave published in 1978"

Nonlinear phenomena in the ionosphere

Abstract: 1. Introduction.- 1.1 Data on the Structure of the Ionosphere.- 1.2 Features of Nonlinear Phenomena in the Ionosphere.- 1.2.1. Nonlinearity Mechanisms.- 1.2.2. Qualitative Character of Nonlinear Phenomena.- 1.2.3. Brief Historical Review.- 2. Plasma Kinetics in an Alternating Electric Field.- 2.1. Homogeneous Alternating Field in a Plasma (Elementary Theory).- 2.1.1.Electron Current-Electronic Conductivity and Dielectric Constant.- 2.1.2.Electron Temperature.- 2.1.3.Ion Current-Heating of Electrons and Ions.- 2.2. The Kinetic Equation.- 2.2.1. Simplification of the Kinetic Equation for Electrons.- 2.2.2. Transformation of the Electron Collision Integral.- 2.2.3. Inelastic Collisions.- 2.3. Electron Distribution Function.- 2.3.1. Strongly Ionized Plasma.- 2.3.2. Weakly Ionized Plasma.- 2.3.3. Arbitrary Degree of lonization-Concerning the Elementary Theory.- 2.4. Ion Distribution Function.- 2.4.1. Simplification of the Kinetic Equation.- 2.4.2. Distribution Function.- 2.4.3. Ion Temperature, Ion Current.- 2.5. Action of Radio Waves on the Ionosphere.- 2.5.1. lonization Balance in the Ionosphere.- 2.5.2. Effective Frequency of Electron and Ion Collisions-Fraction of Lost Energy.- 2.5.3. Electron and Ion Temperatures in the Ionosphere.- 2.5.4. Heating of the Ionosphere in an Alternating Electric Field.- 2.5.5.Perturbations of the Electron and Ion Concentrations.- 2.5.6. Artificial lonization of the Ionosphere-Heating of Neutral Gas.- 3. Self-Action of Plane Radio Waves.- 3.1. Simplification of Initial Equations.- 3.1.1. Nonlinear Wave Equation.- 3.1.2. Nonlinear Geometrical Optics of a Plane Wave.- 3.2. Effect of Nonlinearity on the Amplitude and Phase of the Wave.- 3.2.1. Self-Action of a Weak Wave.- 3.2.2. Self-Action of a Strong Wave.- 3.2.3. Self-Action of Waves in the Case of Artificial lionization.- 3.3. Change of Wave Modulation.- 3.3.1. Weak Wave.- 3.3.2. Change of Amplitude Modulation of Strong Wave.- 3.3.3. Phase Modulation.- 3.3.4. Nonlinear Distortion of Pulse Waveform.- 3.4. Generation of Harmonic Waves and Nonlinear Detection.- 3.4.1. Frequency Tripling.- 3.4.2. Nonlinear Detection.- 3.5. Self-Action of Radio Waves in the Lower Ionosphere.- 4. Interaction of Plane Radio Waves.- 4.1. Cross Modulation.- 4.1.1. Weak Waves.- 4.1.2. Strong Perturbing Wave.- 4.1.3. Resonance Effects near the Electron Gyrofrequency.- 4.2. Interaction of Unmodulated Waves.- 4.2.1. Interaction of Short Pulses.- 4.2.2. Change in the Absorption of a Wave Propagating in a Perturbed Plasma Region.- 4.2.3. Generation of Waves with Combination Frequencies.- 4.3. Radio Wave Interaction in the Lower Ionosphere.- 4.3.1. Cross Modulation.- 4.3.2. Fejer's Method.- 4.3.3. Nonstationary Processes in the Interaction of Strong Radio Waves.- 5. Self-Action and Interaction of Radio Waves in an Inhomogeneous Plasma.- 5.1. Inhomogeneous Electric Field in a Plasma.- 5.1.1. Fundamental Equations.- 5.1.2. Distribution of Density and Temperatures in Plasma.- 5.2. Kinetics of Inhomogeneous Plasma.- 5.2.1. Kinetic Coefficients. Elementary Theory.- 5.2.2. Kinetic Theory.- 5.2.3. Fully Ionized Plasma.- 5.3. Modification of the F Region of the Ionosphere by Radio Waves.- 5.3.1. Modification of the Electron Temperature and of the Plasma Concentration.- 5.3.2. Radio Wave Reflection Region.- 5.3.3. Growth and Relaxation of the Perturbations.- 5.4. Focusing and Defocusing of Radio Wave Beams.- 5.4.1. Nonlinear Geometrical Optics.- 5.4.2. Defocusing of Narrow Beams.- 5.4.3. Mutual Defocusing.- 5.4.4. Thermal Focusing in the Lower Ionosphere.- 6. Excitation of Ionosphere Instability.- 6.1. Self-Focusing Instability.- 6.1.1. Spatial Instability of a Homogeneous Plasma.- 6.1.2. Instability in the Wave-Reflection Region.- 6.2. Resonant Absorption and Resonance Instability.- 6.2.1. Langmuir Oscillations in an Inhomogeneous Plasma.- 6.2.2. Excitation of Plasma Waves.- 6.2.3. Resonance Instability.- 6.2.4. Absorption of Ordinary Radio Waves.- 6.3. Parametric Instability.- 6.3.1. Langmuir Oscillations of a Plasma in an Alternating Field.- 6.3.2. Parametric Excitation of Langmuir Oscillations.- 6.3.3. Parametric Instability in the Ionosphere.- 6.3.4. Dissipative Parametric Instability.

Nonlinear phenomena in the ionosphere

Abstract: 1. Introduction.- 1.1 Data on the Structure of the Ionosphere.- 1.2 Features of Nonlinear Phenomena in the Ionosphere.- 1.2.1. Nonlinearity Mechanisms.- 1.2.2. Qualitative Character of Nonlinear Phenomena.- 1.2.3. Brief Historical Review.- 2. Plasma Kinetics in an Alternating Electric Field.- 2.1. Homogeneous Alternating Field in a Plasma (Elementary Theory).- 2.1.1.Electron Current-Electronic Conductivity and Dielectric Constant.- 2.1.2.Electron Temperature.- 2.1.3.Ion Current-Heating of Electrons and Ions.- 2.2. The Kinetic Equation.- 2.2.1. Simplification of the Kinetic Equation for Electrons.- 2.2.2. Transformation of the Electron Collision Integral.- 2.2.3. Inelastic Collisions.- 2.3. Electron Distribution Function.- 2.3.1. Strongly Ionized Plasma.- 2.3.2. Weakly Ionized Plasma.- 2.3.3. Arbitrary Degree of lonization-Concerning the Elementary Theory.- 2.4. Ion Distribution Function.- 2.4.1. Simplification of the Kinetic Equation.- 2.4.2. Distribution Function.- 2.4.3. Ion Temperature, Ion Current.- 2.5. Action of Radio Waves on the Ionosphere.- 2.5.1. lonization Balance in the Ionosphere.- 2.5.2. Effective Frequency of Electron and Ion Collisions-Fraction of Lost Energy.- 2.5.3. Electron and Ion Temperatures in the Ionosphere.- 2.5.4. Heating of the Ionosphere in an Alternating Electric Field.- 2.5.5.Perturbations of the Electron and Ion Concentrations.- 2.5.6. Artificial lonization of the Ionosphere-Heating of Neutral Gas.- 3. Self-Action of Plane Radio Waves.- 3.1. Simplification of Initial Equations.- 3.1.1. Nonlinear Wave Equation.- 3.1.2. Nonlinear Geometrical Optics of a Plane Wave.- 3.2. Effect of Nonlinearity on the Amplitude and Phase of the Wave.- 3.2.1. Self-Action of a Weak Wave.- 3.2.2. Self-Action of a Strong Wave.- 3.2.3. Self-Action of Waves in the Case of Artificial lionization.- 3.3. Change of Wave Modulation.- 3.3.1. Weak Wave.- 3.3.2. Change of Amplitude Modulation of Strong Wave.- 3.3.3. Phase Modulation.- 3.3.4. Nonlinear Distortion of Pulse Waveform.- 3.4. Generation of Harmonic Waves and Nonlinear Detection.- 3.4.1. Frequency Tripling.- 3.4.2. Nonlinear Detection.- 3.5. Self-Action of Radio Waves in the Lower Ionosphere.- 4. Interaction of Plane Radio Waves.- 4.1. Cross Modulation.- 4.1.1. Weak Waves.- 4.1.2. Strong Perturbing Wave.- 4.1.3. Resonance Effects near the Electron Gyrofrequency.- 4.2. Interaction of Unmodulated Waves.- 4.2.1. Interaction of Short Pulses.- 4.2.2. Change in the Absorption of a Wave Propagating in a Perturbed Plasma Region.- 4.2.3. Generation of Waves with Combination Frequencies.- 4.3. Radio Wave Interaction in the Lower Ionosphere.- 4.3.1. Cross Modulation.- 4.3.2. Fejer's Method.- 4.3.3. Nonstationary Processes in the Interaction of Strong Radio Waves.- 5. Self-Action and Interaction of Radio Waves in an Inhomogeneous Plasma.- 5.1. Inhomogeneous Electric Field in a Plasma.- 5.1.1. Fundamental Equations.- 5.1.2. Distribution of Density and Temperatures in Plasma.- 5.2. Kinetics of Inhomogeneous Plasma.- 5.2.1. Kinetic Coefficients. Elementary Theory.- 5.2.2. Kinetic Theory.- 5.2.3. Fully Ionized Plasma.- 5.3. Modification of the F Region of the Ionosphere by Radio Waves.- 5.3.1. Modification of the Electron Temperature and of the Plasma Concentration.- 5.3.2. Radio Wave Reflection Region.- 5.3.3. Growth and Relaxation of the Perturbations.- 5.4. Focusing and Defocusing of Radio Wave Beams.- 5.4.1. Nonlinear Geometrical Optics.- 5.4.2. Defocusing of Narrow Beams.- 5.4.3. Mutual Defocusing.- 5.4.4. Thermal Focusing in the Lower Ionosphere.- 6. Excitation of Ionosphere Instability.- 6.1. Self-Focusing Instability.- 6.1.1. Spatial Instability of a Homogeneous Plasma.- 6.1.2. Instability in the Wave-Reflection Region.- 6.2. Resonant Absorption and Resonance Instability.- 6.2.1. Langmuir Oscillations in an Inhomogeneous Plasma.- 6.2.2. Excitation of Plasma Waves.- 6.2.3. Resonance Instability.- 6.2.4. Absorption of Ordinary Radio Waves.- 6.3. Parametric Instability.- 6.3.1. Langmuir Oscillations of a Plasma in an Alternating Field.- 6.3.2. Parametric Excitation of Langmuir Oscillations.- 6.3.3. Parametric Instability in the Ionosphere.- 6.3.4. Dissipative Parametric Instability.

Incoherent scatter of radio waves from the ionosphere

Abstract: Systematic studies of the upper atmosphere by the so-called incoherent-scatter technique have now been conducted at a limited number of sites for more than a decade. The article reviews the history of the development of the technique, the basic theory involved and the atmospheric parameters which have been successfully measured, together with a summary of existing facilities and current developments.

Radio Communication in Tunnels

Abstract: The attenuation constant of radio waves in tunnels was obtained experimentally and theoretically. According to this study, the tunnel is a transmission channel of high-pass type. It is found that the higher the frequency, the smaller the attenuation constant. The experimental values of attenuation constants are similar to the theoretical values of the the TE/sub 01/ and EH/sub 11/ and modes when the tunnel is regarded as a circular waveguide with the same cross-sectional area as the tunnel. Radio communication using the tunnel was proven to be fully possible in spite of the standing wave effects due to the interference of the propagation modes.

Ionospheric heating by radio waves: Predictions for Arecibo and the satellite power station

Abstract: The effect of resistive heating by radio waves on ionospheric temperatures, electron densities, and airglow emissions is examined by using numerical ionospheric structure and heat balance codes. Two cases are studied: (1) a 3-GHz, 10-GW microwave beam from a proposed satellite power station and (2) 1-MW and 3-MW beams of 15-MHz radio waves launched by the Arecibo antenna. By intent, these two cases have similar intensities and geometries of resistive heating. The most dramatic heating effects are predicted to occur in the E region, where a thermal runaway will take place. The E region electron temperature will increase from 200°K to roughly 1000°K, and the E region electron density will increase by a factor of about 3. In the F region, where thermal conductivity plays an important role, temperature increases of 200°–500°K will appear along magnetic field lines passing through the radio wave beams. Enhanced emissions in airglow and molecular infrared lines will also occur. Radio wave heating, when combined with the diagnostic capabilities of the Arecibo incoherent scatter radar, will generate new opportunities to measure the rates of atomic physics processes and neutral atmosphere temperatures and composition at D and E region altitudes.

Interferometric locating system

Abstract: A system for determining the position of a vehicle or other target that emits radio waves, which is of the type that senses the difference in time of arrival at spaced ground stations of signals from the vehicle to locate the vehicle on a set of intersecting hyperbolas. A network of four ground stations detects the radio emissions from the vehicle, and by means of cross correlation derives the relative signal delay at the ground stations from which the vehicle position is deduced. Because the signal detection is by cross correlation, no knowledge of the emission is needed, which makes even unintentional radio noise emissions usable as a locator beacon. By positioning one of the four ground stations at an elevation significantly above the plane of the other three stations, a three dimensional fix on the vehicle is possible.

Ionospheric techniques and phenomena

Abstract: One/The Ionospheric Environment.- I / The Atmosphere and the Vertical Structure of the Ionospheric Plasma.- 1.1. Hydrostatic Equilibrium in the Earth's Gravitational Field.- 1.2. The Interaction Between the Ultraviolet Solar Spectrum and the Atmosphere.- 1.3. Stratifications of the Ionosphere.- II / The Latitudinal Structure of the Ionosphere and the Magnetosphere.- 2.1. Terrestrial Magnetism.- 2.2. The Interaction between the Solar Wind and the Geomagnetic Field.- 2.3. The Dynamics of Charged Particles.- 2.4. Magnetospheric Activity and Substorms.- Two/The Techniques of Ionospheric Measurements.- III / Propagation of Radio Waves.- 3.1. Electromagnetic Waves in Plasmas.- 3.2. The Reflection of Radio Waves by the Ionosphere.- 3.3. Phase Effects with High Frequency Waves.- 3.4. Group Effects with Lower Frequency Waves.- 3.5. The Effects of Collisions.- IV / Scattering of Radio Waves.- 4.1. Quasi-Specular Reflexion from Ionospheric Irregularities.- 4.2. Scattering from VolumeTlasma Fluctuations.- 4.3. Implementation of Incoherent Scatter Sounding.- V / Sampling With Space-Borne Probes.- 5.1. The Langmuir Characteristic.- 5.2. Specific Problems Connected with Space Vehicles.- 5.1. Plasma Probes.- 5.2. Electrostatic Analyzers.- 5.3. Mass Spectrometers.- Three/The Interpretation of Ionospheric Phenomena.- VI / Chemistry of Charge Conservation.- 6.1. Ion Chemical Processes.- 6.2. The Chemical Structure of the Ionosphere.- 6.3. Photoionization.- 6.4. Corpuscular Ionization.- 6.5. Meteor Ionization.- VII / Electrodynamics of Momentum Transfer.- 7.1. The Bulk Motions of Ions and Electrons.- 7.2. Ionospheric Electric Fields and Currents.- 7.3. The Distribution of Hydrogen Ions and the Upper Ionosphere.- 7.4. The Behaviour of Atomic Oxygen Ions and the F layer.- 7.5. The Formation of Sporadic E layers at Temperate Latitudes.- VIII / Thermodynamics of Energy Balance.- 8.1. Energy Budget of the Charged Particles.- 8.2. Electron and Ion Temperatures in the Mid and Low Latitude Regions.- 8.3. Geomagnetic Control of Ionospheric Temperature.- References.

Dependence of depolarization on incident polarization for 19-GHz satellite signals

Abstract: Rain and ice crystals depolarize radio waves along earth-satellite propagation paths. The magnitude of this depolarization is a function of incident polarization angle and is minimized when polarization and depolarizer symmetry axes coincide. A technique is presented for a direct determination of the medium's attenuation and depolarization for any incident polarization, based on measurements taken at two orthogonal polarizations. Some sample results from this technique are presented, using data collected at Crawford Hill, New Jersey using the 19-GHz COMSTAR satellite beacon.

Ionospheric emission caused by an intense radio wave

Abstract: Intense rf pulses at a frequency ..omega../sub 1/ near the electron gyrofrequency ..omega../sub H/ cause an intensification of the red emission line of atomic oxygen at the wavelength lambda=6300 A in the F layer of the ionosphere at an altitude zapprox.200 km. The experiments also reveal an anomalous broadband absorption of radio waves when the ionosphere is perturbed at a frequency ..omega../sub 1/approx. =..omega../sub H/. This effect is shown to be in accordance with the theory of resonant absorption. The accelerated electrons are apparently due to the excitation of a parametric instability.

Plasma waves in the magnetosphere

Abstract: A large variety of plasma wave phenomena are seen in the Earth's magnetosphere. Attempts at the theoretical explanation have had some successes, including wave induced loss of radiation belt particles and the Kelvin–Helmholtz instability source of geomagnetic pulsations. But there are also areas where theory needs more development: for example, on the ion wave turbulence seen on auroral magnetic flux tubes, the role of anomalous resistivity and the origin of the terrestrial kilometric radio waves.

Hysteresis effect in the artificial excitation of inhomogeneities in the ionospheric plasma

Abstract: A hysteresis effect is discovered in the dependence of the scattering cross section of artificial ionospheric inhomogeneities on the intensity of the radio waves exciting them. The thresholds for the excitation and cutoff of the plasma instability are determined and the dependence of the magnitude of its fluctuations on the power of the exciting transmitter is established.

Radio wave absorbing wall for building material

Abstract: PURPOSE:To make the band of the frequency characteristic of the reflection loss of a structure body of concrete, mortar, etc., wider and, at the same time, to constitute the structure body in a simple easily manufacturable structure so as to reduce the manufacturing cost of the structure body by suppressing the influence of the dielectric characteristic of the structure body on ferrite plates to a low level. CONSTITUTION:In the hollow sections 31 of a concrete panel 30 constituted in an insulating hollow structure body having the hollow sections 31 which are continuously formed in the direction of the magnetic field of arriving radio waves, ferrite plates 1 are continuously arranged in the direction of the magnetic field so that an air layer 35 can be formed behind the plates 1 when viewed from the arriving direction of the radio waves and a metallic mesh 38 is provided as a radio wave reflecting body behind the concrete panel 30.

Hearing aid with signals modulated onto radio waves - may include optical radiation for transmission from microphone unit to loudspeaker unit

Abstract: The hearing aid has its microphone located in a transmitter and its loudspeaker (which fits into the user's ear) located in a receiver. The transmitter and receiver are spacially separate and connected via free space. The free-space link between transmitter and receiver may be via high frequency radio waves or via light, esp. IR. Both the transmitter and receiver contain their own dc supplies such as batteries. The receiver contains a device to limit power consumption during the breaks in transmission. Alternatively, the receiver may have no dc supply of its own; in this case the transmitter transmits at a high power.

Radar wave response device

Abstract: PURPOSE:To make possible heat resistance, impact resistance, shielding of radio waves and light, etc. with simple constitution and obtain the radio wave response device which operates surely by housing the radio wave response apparatus in the specified exterior material which is bisectable by means of a cord. CONSTITUTION:A float 1 provided with receiving-transmitting antennas, radio wave response part, receiver-transmitter, incandescent lamp, source battery, etc. is housed in the bisected external materials 5A, 5B which have heat insulation, impact resistance and radio wave and light shield characteristic, and it permits its inspection through the inspection window 5-8 provided to the external material 5A without radiating reponse radio waves and incandescent lamp light to the outside. On the other hand, the other end of the connecting cord 102 which is connected to the float 1 and is extending outward from the coupling part of the external materials 5A and 5B is connected to a life buoy 7. At the time of actual use such as shipwreck or the like, the external materials 5A, 5B are bisected by the cord 1-2 and the float 1 floats on the water surface, thus the radio wave response device of good heat insulation, impact resistance and radio wave and light shield characteristic is provided with the simple constitution.

Incoherent scattering of radio waves by whistler mode oscillations in the ionosphere

Abstract: The received power spectrum in incoherent scatter can contain two sharp resonances removed from the center frequency. The first is due to ordinary electrostatic plasma oscillations and is known as the plasma line. The second depends on the presence of a magnetic field and corresponds to the high-frequency end of the whistler mode in magnetoionic theory. Here we report an experimental detection of this second resonance.

Radio interference bucker apparatus

Abstract: An apparatus for intercepting radio waves emitted from a relatively local interference radio-wave-emitting source and processing the same so that they may be fed into the antenna terminal of a radio wave receiver for accomplishing substantially interference-free reception of distant radio wave stations. An antenna suited for only local reception provides the interfering radio wave energy to the bucker apparatus. Therein it is amplified a selected amount and the phase thereof altered by a continuously adjustable delay means to accomplish the desired cancellation of interference by phase opposition of the interfering signal from the bucker with respect to the interfering signal as it is received at the antenna terminal of the radio wave receiver.

Scattering of Radio Waves

Abstract: The use of the word ‘scattering’ or ‘scatter’ is rather loose, and the distinction between the propagation of waves as discussed in the preceding chapter, and in this one, is somewhat artificial. What we have been concerned about so far is the effect on wave propagation of the fundamentally one-dimensional, plane stratified structure of the ionospheric plasma (except for magnetic field direction); furthermore we have supposed that its characteristics are homogeneous and slowly varying on the scale of the probing electromagnetic wavelength and frequency. We now turn to propagation phenomena and techniques which result from the more or less ubiquitous and permanent departure from such simple conditions in the ionosphere, that is to say, to the influence on wave propagation of the existence of ever changing irregular blobs of excess or deficiency in ionization density. In general, as we shall see, a new dimension is brought in by scattering techniques as they allow the observation of ionospheric motions.

Intensity of x-ray solar radiation and the value of the anomalous absorption of radio waves during periods of sudden ionospheric disturbances

Abstract: An experimental statistical dependence is obtained between the intensity of the x-ray radiation of the sun in the range 1–8 a (I1−8) and the value of the anomalous absorption of radio waves at a frequency of I=13 MHz during periods of sudden ionospheric disturbances. This dependence has the form γ13 ∼ I1–80.8cos χ, and can be used for the operative classification of bursts of x-ray radiation. Its character is explained by a decrease in the coefficient of the losses of electrons with a rise in the intensity of the x-ray radiation.