scholarly journals On wireless interference phenomena between ground waves and waves deviated by the upper atmosphere

1926 ◽  
Vol 113 (764) ◽  
pp. 450-458 ◽  
Keyword(s):  
Short Distance ◽  
Wave Length ◽  
Path Difference ◽  
Upper Atmosphere ◽  
Wireless Transmission ◽  
Continuous Change ◽  
Carrier Wave ◽  
Night Time ◽  
Side Band ◽  
Atmospheric Waves

In previous communications we have outlined two experimental methods of examining the effects of the atmospheric ionized layer in short-distance wireless transmission. In the first type of experiment the existence of night-time interference phenomena between two sets of waves was demonstrated by changing the wave-length of the transmitter continuously through a small range and observing the resultant maxima and minima of signal intensity. It was suggested that such interference took place between ground waves and waves deviated through large angles by the upper atmosphere. In the second type of experiment the angle of incidence of such atmospheric waves at the earth’s surface was measured by comparing the magnitude of the electric and magnetic forces in the stationary wave system produced at the ground. The results of these experiments were interpreted as yielding a direct experimental proof of the existence of the Kennelly-Heaviside layer, and also as demonstrating that the “fading” of broadcasting signals at moderate distances from the transmitter was due mainly to interference phenomena between two sets of waves arriving at a receiver with an appreciable path difference. But there still remained the problem of the cause of the natural succession of interference effects which constitutes fading at moderate distances, and which takes place continuously throughout the night-time. These variations indicate either that the phase relation between the ground and atmospheric waves is continually changing at night, or that intensity or polarization changes of the atmospheric waves are taking place. In considering possible causes of phase variations, let us examine the relation between the path difference and the wave-length for a typical case of short-distance transmission. Let D represent the path-difference between the ground and atmospheric rays. Then the atmospheric ray arrives n wavelengths behind the ground ray at the receiver, where n = D/ λ , and λ is the wave-length. It has been mentioned above that a possible cause of the natural signal variations which occur at night is a continuous change of phase which would be produced by a change in n . Such a change might be brought about by changes in D, or in λ , or in both simultaneously, and it is necessary to decide between these possibilities. Changes in D might be brought about by a variation in the height of the layer, so that a Döppler effect at "reflection” is produced. In such a case the signal variation might be regarded as the beating between the ground-ray frequency and the reflected-ray frequency. On the other hand, if there is a slow variation of transmitter frequency, the frequency of the atmospheric ray would be different from that of the ground ray, because of the difference in times of emission from the transmitter, and, again, the natural changes might be regarded as beats. The suggestion has already been made by Breit that fading is due to the modulation of the carrier wave, and thus to change of wave-length. In the latter connection we have to consider the variation of both carrier wave and side-band frequencies. The results of our earlier experiments suggested that the change of side-band frequency necessary for the wireless transmission of music is sufficient to produce selective frequency fading, and thus a certain amount of distortion. But with the normal type of modulation the signal intensity is chiefly dependent on the intensity of the carrier wave, and the question whether a slow “swing” of the carrier wave is responsible for such fading (which is observed whether the carrier wave is modulated or unmodulated) seems still unanswered. The question, of course, is equally of interest in both continuous wave telegraphy and wireless telephony.

scholarly journals On the nature of wireless signal variations—I

1927 ◽  
Vol 115 (771) ◽  
pp. 291-305 ◽  
Keyword(s):  
Continuous Wave ◽  
Wave Length ◽  
Length Change ◽  
Path Difference ◽  
Angle Of Incidence ◽  
Continuous Change ◽  
Interference System ◽  
Variable Nature ◽  
Wireless Signal ◽  
Magnetic Vectors

In a recent communication two experimental methods of investigating the atmospheric deflection of electric waves have been described. In one of these methods interference phenomena, which take the form of a succession of signal maxima and minima at the receiving station, are artificially produced by a small continuous change of transmitter wave-length. From the study of these phenomena information relating to the path difference and relative intensities of the ground and atmospheric waves may be deduced. In the second type of experiment the angle of incidence of the down-coming waves is deduced from an examination of the electric and magnetic vectors in the stationary interference system produced at the ground by the waves incident from above and reflected at the earth’s surface. In a more recent communication some further results, obtained by means of the “wave-length change” method, have been described, which indicate that the variations of signal intensity produced at moderate distances from a continuous-wave transmitting station are due to the variable nature of the rays returned from the upper atmosphere, and not to slight variations of transmitter wave-length. In this second communication, however, certain points were left unelucidated. For example, it was pointed out that the wave-length change experiments gave us no information as to the relative importance of the parts played by changes in intensity, phase polarization, or angle of incidence of the downcoming waves in producing the ordinary nocturnal signal variations. The development of the second type of experiment mentioned above (in which the electric and magnetic vectors of the stationary interference system produced at the ground are examined) has yielded considerable information on these and allied points, and it is with these developments that the present communication deals. The refinements in the technique of the original experiments may be grouped under three heads. In the first place, we have employed automatic photographic registration for recording the galvanometer deflections corresponding to the magnitudes of various vectors. Such registration is specially useful when simultaneous records of the variations of any two vectors are required.

scholarly journals On some measurements of the equivalent height of the atmospheric ionised layer

1930 ◽  
Vol 126 (803) ◽  
pp. 542-569 ◽  
Keyword(s):  
Wave Length ◽  
Length Change ◽  
Early Morning ◽  
Path Difference ◽  
Research Station ◽  
Angle Of Incidence ◽  
Continuous Change ◽  
Primary Object ◽  
Atmospheric Disturbances ◽  
Aerial Systems

In previous communications various experimental methods of examining the characteristics of downcoming wireless waves have been described. Of these methods by far the most useful has proved to be that which involves a small continuous change of transmitter wave-length, by means of which there is produced at a receiving station a succession of interference maxima and minima between ground waves and waves deviated by the upper atmosphere. By using loop and antenna receiving systems in several different ways it has been possible to estimate, from a comparison of the interference “fringe” amplitudes, the relative intensities of the ground and atmospheric waves and also the angle of incidence of the latter at the ground; while a comparison of the phase differences between the two sets of waves, as deduced from the interference “fringes” recorded on different types of aerial systems, has yielded information relating to the polarisation of downcoming waves. In all such investigations, however, the number of “fringes” produced by a known wave-length change has been found, even when the determination of that number was not the primary object of the experiment. In this way the equivalent path difference for the ground and atmospheric wave tracks has been calculated as a routine measurement from which the equivalent height of the ionised layer could be deduced. In the course of such investigations carried out at the Peterborough Radio Research Station, much evidence has therefore accumulated relating to the diurnal variation of the equivalent height of those regions in the atmosphere which are responsible for the deviation of wireless waves. As was pointed out in the first communication dealing with the work of the station, considerable interest is, in the study of wireless wave propagation, attached to the transitional periods of sunrise and sunset. As the experiments under discussion were usually carried out on wave-lengths of from 300 to 600 metres ( i. e ., on frequencies of from 1000 to 500 kilocycles per second) the study of the sunset period was, except on rare occasions, impossible, because of interference from broadcasting transmitters. The majority of the tests therefore took place during the sunrise period when, in addition to the advantage of the low level of artificial interference, there was also that of the early morning minimum of natural atmospheric disturbances. In carrying out such early morning runs it was soon found that, in the few hours before sunrise, the signal records showed the presence of both primary and secondary interference maxima and minima, indicating the simultaneous reception of two or more downcoming rays. After sunrise the phenomena became simpler and smooth “fringes” were recorded. This latter particular period was therefore especially suitable for the determinations of the characteris­tics (intensity, angle of incidence, polarisation, etc.) of downcoming waves already described. The present communication, is in part an attempt to elucidate these pre-sunrise phenomena and in part an introduction to two papers which are to follow, since it was the study of the significance of multiple downcoming rays which led to the investigation of the subject with which these two papers respectively deal, namely, the simultaneous reception of downcoming waves at several receiving stations and the use of shorter wave-lengths.

scholarly journals On some short-wave equivalent height measurements of the ionized regions of the upper atmosphere

1930 ◽  
Vol 128 (807) ◽  
pp. 159-178 ◽  
Keyword(s):  
Wave Length ◽  
Good Deal ◽  
Short Wave ◽  
Wave Intensity ◽  
Upper Atmosphere ◽  
Frequency Change ◽  
Electronic Density ◽  
Short Waves ◽  
F Region ◽  
E Region

The present paper continues the account of wireless investigations of the ionized regions of the upper atmosphere given in two previous papers. The results discussed in it consist chiefly of measurements of the equivalent heights of the ionized regions made simultaneously at two or three receiving stations with wave-lengths of the order of 100 metres. The frequency-change method of measuring the equivalent height was used throughout. 2. Extension of Equivalent Height Measurements to the Use of Short Waves . The experiments described previously were continued with shorter wave-lengths with two objects in view. In the first place it had been found that 400-metre waves penetrated the lower ionized region (E region) only on certain nights, and then only during the few hours before dawn. This result clearly showed that penetration of this region was most likely when the density of ionization was least. But, according to most theories of wireless propagation, a greater electronic density is required to reflect or refract short waves than is the case with long waves, so that it was anticipated that by reducing the wave-length below 400 metres it might be possible to penetrate E region over a longer period of time during the night than had been possible when 400-metre waves had been used. In this way it was hoped to make a more detailed study of the variation of the equivalent height of the upper region (F region) which had been found to reflect 400-metre waves on the occasion when they had penetrated the normal E region. Secondly, since it is known that the attenuation of the ground waves increases rapidly as the wave-length is reduced below, say, 400 metres, it was expected that, with the use of shorter waves, the ratio of the values of downcoming wave intensity and ground wave intensity would be much increased at all stations. Such an increase, it was expected, would make it possible to continue the measurements of equivalent heights, in general, a good deal further into the daylight hours. Such daylight measurements on longer waves had previously been found difficult, because of the relative weakness of the intensity of the downcoming waves as compared with that of the ground waves.

scholarly journals Ionosphere Influenced From Lower-Lying Atmospheric Regions

2021 ◽  
Vol 8 ◽  
Author(s):  
Petra Koucká Knížová ◽  
Jan Laštovička ◽  
Daniel Kouba ◽  
Zbyšek Mošna ◽  
Katerina Podolská ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Source Region ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Small Scale ◽  
Atmospheric Waves ◽  
Ionospheric Variability ◽  
Secular Variations ◽  
Wide Scale ◽  
Academy Of Sciences

The ionosphere represents part of the upper atmosphere. Its variability is observed on a wide-scale temporal range from minutes, or even shorter, up to scales of the solar cycle and secular variations of solar energy input. Ionosphere behavior is predominantly determined by solar and geomagnetic forcing. However, the lower-lying atmospheric regions can contribute significantly to the resulting energy budget. The energy transfer between distant atmospheric parts happens due to atmospheric waves that propagate from their source region up to ionospheric heights. Experimental observations show the importance of the involvement of the lower atmosphere in ionospheric variability studies in order to accurately capture small-scale features of the upper atmosphere. In the Part I Coupling, we provide a brief overview of the influence of the lower atmosphere on the ionosphere and summarize the current knowledge. In the Part II Coupling Evidences Within Ionospheric Plasma—Experiments in Midlatitudes, we demonstrate experimental evidence from mid-latitudes, particularly those based on observations by instruments operated by the Institute of Atmospheric Physics, Czech Academy of Sciences. The focus will mainly be on coupling by atmospheric waves.

The “layered method” – A third method of floodlighting

2019 ◽  
Vol 52 (5) ◽  
pp. 641-653 ◽  
Author(s):  
W Żagan ◽  
K Skarżyński
Keyword(s):  
Short Distance ◽  
State Of The Art ◽  
Rapid Development ◽  
Light Distribution ◽  
New Method ◽  
Night Time ◽  
Visual Effect ◽  
Lighting Technology ◽  
Advantages And Disadvantages ◽  
Light Line

The main aim of this work is to present a new method of floodlighting – the ‘Layered Method’. It has been possible to create this method due to the rapid development of linear luminaires with LEDs. When luminaires are located a very short distance from an illuminated wall and are directed at a low angle, the layered floodlighting method gives an unusual and interesting visual effect. In this situation, the length of light distribution on the illuminated wall is the same as the length of the light line and is rather short in width. This gives the opportunity of creating the effect of a layer of light, which can be used, for example, to illuminate Renaissance tenement houses and all types of longitudinal architectural details, such as tympanums or balusters. This paper presents the state-of-the-art use of the layered method of floodlighting. All advantages and disadvantages, in terms of lighting technology and architecture, are carefully described. The ideas contained in this paper could be useful for those who are interested in making architectural objects more beautiful by means of illumination at night-time.

scholarly journals Further measurements on wireless waves received from the upper atmosphere

1927 ◽  
Vol 116 (775) ◽  
pp. 682-693 ◽  
Keyword(s):  
Closed Loop ◽  
Wave Length ◽  
Direct Proof ◽  
Relative Magnitude ◽  
Upper Atmosphere ◽  
Circle Plane ◽  
The Earth ◽  
Direction Finder ◽  
Short Period ◽  
Attention To Detail

In previous papers the authors have described the development of experimental methods of measuring the directions and relative intensities of both the electric and magnetic forces in wireless waves received at the earth’s surface from a distant transmitting station. In this work it was seen that the detection of the arrival of waves deflected from the upper atmosphere, and polarised with their electric force in a horizontal plane, was rendered difficult owing to the relatively great reflecting powTer of the earth resulting from its high conductivity. By a suitable choice of wave-length and careful attention to detail in the design and construction of the apparatus, however, the methods employed enabled measurements to be made on both vertically and horizontally polarised waves. The results of such measurements enabled a direct proof to be given of the fact that the fading of wireless signals on a vertical aerial and the variations of bearings experienced on the closed-loop type of wireless direction-finder are due to the reception respectively of vertically and horizontally polarised waves deflected from the upper atmosphere in their passage from the transmitter to the receiver. On arrival at the receiver, these indirect or atmospheric waves interfere with the direct or ground waves, in a manner determined by their relative magnitude and phase, and produce the intensity and apparent direc­tional variations mentioned above. The results of such interference phenomena have been investigated experimentally by Appleton and Barnett and by Holling-worth. In a more recent publication the present authors have provided experimental evidence showing that the path of the indirect waves is confined to the great circle plane between the transmitter and receiver. The measurements of the quantities in the received waves as previously described by the authors were confined to observations on the transmissions from the Bournemouth broadcasting station over a short period. The object of the present paper is to describe the continuation of these measurements and their extension to the transmissions from other stations.

scholarly journals On the action of ultra-violet sunlight upon the upper atmosphere

1937 ◽  
Vol 160 (901) ◽  
pp. 155-173 ◽  
Keyword(s):  
Wave Length ◽  
Charged Particles ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
Magnetic Storms ◽  
Upper Atmosphere ◽  
The Sun ◽  
Polar Aurora ◽  
Night Sky ◽  
Photochemical Action

The ordinary solar spectrum extends, as is well known, to about λ2913, the more ultra-violet parts being cut off by ozone absorption in the upper atmosphere. We have thus no direct knowledge of the distribution of intensity in the solar spectrum beyond λ2913, as it will appear to an observer situated outside the atmosphere of the earth. But it is now recognized that a number of physical phenomena is directly caused by the photochemical action of this part of sunlight on the constituents of the upper atmosphere. Such phenomena are (1) the luminous spectrum of the night sky and of the sunlit aurora, (2) the ionization in the E, F and other layers which is now being intensely studied by radio-researchers all over the world, (3) the formation and equilibrium of ozone (see Ladenburg 1935), (4) magnetic storms and generally the electrical state of the atmosphere. Formerly it was a debatable point whether some of these phenomena were not to be ascribed to the action of streams of charged particles emanating from the sun. There seems to be no doubt that the polar aurora and certain classes of magnetic storms are to be ascribed to the bombardment of molecules of N 2 and O 2 by such charged particles, for these phenomena show a period which is identical with the eleven year period of the sun, and are found in greater abundance, the nearer we approach the magnetic poles. But there now exists no doubt that the ionization observed by means of radio-methods in the E and F 1 regions, their variation throughout day and night, and at different seasons is due to the action of ultra-violet sunlight. This was decisively proved by observations during several total solar eclipses since 1932 (Appleton and Chapman 1935). The luminous night-sky spectrum, though it has certain points of similarity to the polar aurora, is on the whole widely different, and is found on nights free from electrical disturbances. The prevailing opinion is that it is mainly due to the ultra-violet solar rays, i. e. in the course of the day sunlight is stored up by absorption by the molecules in the upper atmosphere, and again given up during the night, in one or several steps, as a fluorescence spectrum. According to S. Chapman (1930) the formation of the ozone layer and its equilibrium under different seasonal conditions is also to be mainly ascribed to the action of ultra-violet sunlight. In the following paper an attempt will be made to discuss some of these questions in as rigorous a way as is possible with our present knowledge. It is evident that an adequate discussion is possible only if we have a good knowledge of (1) the distribution of intensity in the solar spectrum beyond λ2900, (2) the photochemical action of light of shorter wave-length than λ2900 on the constituent molecules of the upper atmosphere, which are mainly oxygen and nitrogen. We shall first consider (1).

scholarly journals PROSES DESTINATION BRANDING DALAM MEMBENTUK CITRA TUJUAN WISATA MUSEUM INDONESIA

2019 ◽  
Vol 9 (2) ◽  
pp. 15-34
Author(s):  
Yoyoh Hereyah ◽  
Rastri Kusumaningrum
Keyword(s):  
Public Space ◽  
Elaboration Likelihood Model ◽  
Path Difference ◽  
Elaboration Likelihood ◽  
Community Members ◽  
Night Time ◽  
Destination Branding ◽  
Likelihood Model ◽  
Personal Approach ◽  
Publishing Community

Museum tourist developments in Indonesia continued to show seriousness in efforts utilization as a public space with active people involvement in the museum activities, especially community. However, views on the museum is fashioned, old, boring and spooky still dominant in the society. This study further to see how the collaboration between government and the community in doing destination branding in order to change society's view so as to form a positive image destination stronger. The goal is to analyze the implementation of destination branding by the community through exposure program to finally persuade others to contribute actively in destination branding by using elaboration likelihood models. How the program’s exposure by the community contribute to the process of destination branding museum tourism? How community members elaborate the persuasion messages in the exposure program if analyzed using the elaboration likelihood model theory? The method used is by interview and search for document data from the Komunitas Jelajah Budaya. The results showed that the application of the destination branding museum tourism of Indonesia by the Komunitas Jelajah Budaya with providing message exposure from Program Jelajah Kota Toea and Night Time Journey At The Museum more emphasis on personal approach, word of mouth and packaging programs that persuade people who have the motivation and the need for the message, which is then analyzed using the elaboration likelihood model and show the path difference receiving messages through the central and peripheral factors these different motivations, needs and ability to evaluate the message which then forms a change in attitude. The author recommends to make persuasive messages that more interesting in publishing community programs so the main message in process of destination branding of museum tourism can be elaborated properly by visitors or community members.

Modeling the propagation of atmospheric waves from various tropospheric disturbances and studying their influence on the upper atmosphere

2020 ◽  
Author(s):  
Yuliya Kurdyaeva ◽  
Olga Borchevkina ◽  
Sergey Kshevetskii
Keyword(s):  
Gravity Waves ◽  
Coastal Region ◽  
Internal Gravity Waves ◽  
Travelling Wave ◽  
The State ◽  
Upper Atmosphere ◽  
Small Scale ◽  
Research Project ◽  
Atmospheric Waves ◽  
The Earth

<p>The atmosphere and ionosphere are a complex dynamic system, which is affected by sources, caused both by internal processes and external ones. It is known that atmospheric waves propagating from the troposphere to the upper atmosphere make a significant contribution to the state of this system. One of the regular sources of such waves are various tropospheric disturbances caused, for example, by meteorological processes. Numerical modeling is an effective tool for studying these processes and the effects they cause. However, a number of problems arise, while setting up numerical experiments. The first is that most atmospheric models use hydrostatic approximation (which does not allow the resolution of small-scale perturbations) and work for a limited range of heights (which does not allow studying the relationship between the lower and upper atmosphere). This demands an accurate selection of the model in accordance with the stated research goals. The second problem is the difficulty of direct definition of the wave tropospheric sources, that was mentioned before, due to the lack of experimental information for their detailed description. The authors proposed, researched and tested a way to solve this problem. It was shown that the solution of the problem of waves propagation from a certain tropospheric source is completely determined by the pressure field at the surface of the Earth. This work is devoted to solving various problems using this approach.</p><p>This study presents the results of calculations of the propagation of infrasound and internal gravity waves from tropospheric disturbances given by pressure variations at the surface of the Earth. The experimental data associated with various meteorological events and the passage of the solar terminator were obtained both directly - by a network of microbarographs in the studied region, and indirectly - based on the data from the LIDAR signal intensity and temperature changes in the coastal region. The calculations were done using the non-hydrostatic numerical model “AtmoSym”. The characteristics of atmospheric waves generated by such sources are estimated. The effect from a tropospheric sources on the state of the upper atmosphere and ionosphere is investigated. The physical processes that determine the change in atmospheric parameters are discussed.  It is shown that the main contribution from wave disturbances generated by meteorological sources belongs to infrasound. Infrasound and internal gravity waves can be sources of travelling wave packets and can also cause a sporadic E-layer.</p><p>The study was funded by RFBR and Kaliningrad region according to the research project  19-45-390005 (Y. Kurdyaeva) and  RFBR to the research project  18-05-00184 (O. Borchevkina).</p>

The Propagation of Radio Waves in an Ionised Atmosphere

1931 ◽  
Vol 27 (4) ◽  
pp. 578-587 ◽  
Author(s):  
D. Burnett
Keyword(s):  
Wave Length ◽  
Upper Atmosphere ◽  
Radio Waves ◽  
Free Electrons ◽  
Positive Ions ◽  
Electrons And Ions ◽  
Method Of Solution ◽  
Velocity Of Propagation ◽  
The Waves ◽  
Electric Waves

Larmor has shown that if the upper atmosphere contains electrons (charge ε, mass m, density ν) and if collisions between these electrons and molecules—and also the forces between the electrons themselves—are negligible, then electric waves are propagated as if the dielectric constant of the medium were reduced by , from which it appears that, so long as the approximations are valid, the velocity of propagation of the waves can be increased indefinitely by increasing either the electron density or the wave-length λ. Several later authors have attempted to take account of the collisions between electrons and molecules, assuming free paths or velocities according to Maxwell's laws for a uniform gas, and it appears that the above law holds only for short waves; but it is doubtful how far the properties of a uniform gas can be assumed when periodic forces are acting. In the first part of this paper an alternative method of solution is given by means of Boltzmann's integral equation for a non-uniform gas, the analysis being similar to that used by Lorentz in discussing the motion of free electrons in a metal. Only the case when ν is small is considered, i.e. the interactions of electrons with one another and with positive ions are neglected. How far it is possible to increase the velocity of propagation by increasing ν is a more difficult question, but it seems possible that the forces between the electrons and ions may impose a limit just as collisions with neutral molecules limit the effect of increasing the wave-length.

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