Effective earth radius factor prediction and mapping for ondo. The seasonal effective earth radius factor statistics obtained from the radiosonde measurements are then interpolated, gridded and presented in contour maps to cover the rest of the country for the four seasons defined by itu. The effective earth radius, or kfactor, is defined in terms of. A large set of 14 years of reliable local radiosonde meteorological data, from 1990 to 2003, has been used to calculate the effective earth radius and point. The kfactor is a multiplying factor which helps to assume a hypothetical increased earth radius known as effective earth radius a e such that. To find the distance between the surface and the center of. Shannon central research and development department, experimental station, e. In average atmospheric conditions, the four third 43 value of median k. It is the radius of a hypothetical spherical earth, without atmosphere, for which propagation paths follow straight lines, the heights and ground distances being the same as for the actual earth in an atmosphere with a constant vertical gradient of refractivity. Effective potential, and gravity the expression for the energy of centralforce motion was. Meteorological characterization of effective earth radius factor k. Each of these situations is summarized in terms of the effective earth radius and.
We can treat this as a onedimensional problem if we define an effective potential. The earths atmosphere has characteristics that affect the propagation of radio. Doerry prepared by sandia national laboratories albuquerque, new mexico 87185 and livermore, california 94550 sandia national laboratories is a multiprogram laboratory managed and operated by sandia corporation. Effective radius of the earth radius of a hypothetical spherical earth, without atmosphere, for which propagation paths are along straight lines, the heights and ground distances being the same as for the actual earth in an atmosphere with a constant vertical gradient of refractivity.
Effective earth radius factor prediction and mapping for ondo state, south western nigeria. Determination of the effective earth radius factor and its impact on. Distribution of radio refractivity gradient and effective. The calculated values of effective earth radius factor showed a variation between 1. The radius of a hypothetical earth for which the distance to the radio horizon, assuming rectilinear propagation, is the same as that for the actual earth with an assumed uniform vertical gradient of atmospheric refractive index. Historical and common navigation methods there are an infinite number of paths between two points on the earth.
Determination of atmospheric effective earth radius factor kfactor. Therefore errors in prediction techniques must be minimal for optimal performance. The effective earth radius factor, usually denoted by k, is defined as the effective earth radius divided by the actual earth radius. Calculation of effective earth radius and point refractivity gradient in uae. Effective earth radius scale factors are given as a function of transmitter altitude for. The effective earth radius is a scaling of the actual earth radius. The referential grain size and effective porosity in the. Since ionic radius is a very useful characteristic for understanding partitioning of trace elements, it is imperative that we know how these values are determined.
Eduediuyai dan, constance kalu, ogungbemi emmanuel oluropo, empirical validation of effective earth radius adjustment factors for earth bulge and diffraction loss parameters computation, international journal of systems science and applied mathematics. Engineers refractive effects prediction system ereps. Effective earth radius matlab effearthradius mathworks. Earth curvature and atmospheric refraction effects on radar signal propagation armin w. This syntax uses the default value of 39e9 for the gradient, making the effective radius approximately 43 of the actual earth radius. Particularly, the secondary radio parameters remain very important in carrying out these estimations especially the concept of effective earth radius. Analysis of variation in the vertical profile of radio. Iec 60050 international electrotechnical vocabulary. Estimation of clearair atmospheric effective earth radius kfactor. Kfactor is the ration of effective earth radius and true earth radius 14 15 16. An empirical set of effective ionic radii has been compiled by the use of techniques similar to those of goldschmidt.
Pdf a large set of 14 years of reliable local radiosonde meteorological data, from 1990 to 2003, has been used to calculate the effective earth. Earth curvature and atmospheric refraction effects on radar. Earth curvature and atmospheric refraction effects on. Empirical validation of effective earth radius adjustment. Effective earth radius factor prediction and mapping for. Meteorological characterization of effective earth radius factor kfactor for wireless radio link over akure, nigeria. Here, radio signals travel on a straight line path along the earths surface and go out to space unobstructed. Effective means that v acts like a potential energy, even though it isnt one there is no force corresponding to the.
The radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the earth. This study was carried out in calabar, southsouth nigeria with three years atmospheric parameters data obtained from nigerian meteorological agency nimet. Its value ranges from 6,378 km 3,963 mi at the equator to 6,357 km 3,950 mi at a pole. A central database, the radius server, maintains network security data such as user profiles and.
Earth radius is the distance from the center of earth to a point on its surface. For ease of geometrical analysis, these waves are represented as straight lines then compensation is done by assuming an imaginary earth radius, otherwise referred to as effective earth radius, r. The earth is approximately a sphere and therefore, for some cases, this approximation is adequate. In previous work a model was developed to predict the annual average cumulative. The effective earth radius factor kfactor is an important parameter in the radio propagation and radio applications.
For microwave link design, some parameters such as the effective earth radius factor, and the point refractivity gradient, must be set carefully to optimize its performance. Re effearthradius returns the effective radius of spherical earth in meters. The pdf model used has the following basic form 19, 21. Meteorological characterization of effective earth radius. The effective earth radius factor k can be calculated 12, 14, 16, 17. Effective earth radius scale factors are given as a function of transmitter altitude for selected values of surface refractivity. Thus, k may be expressed in terms of refractivity gradient, dndh as 3, 4. Rh d1ap represents the hypothetical hydraulic radius of. The radius used was 3 a 2 b, which is the radius of a sphere with. Effect of centrifugal force on ocean and earth radius. In this presentation, we present models for determining the probability density function pdf of the effective earth radius factor for botswana as a means of predicting the kfactor variation. Here, radio signals travel on a straight line path along the earth s surface and go. Pier b online seasonal distribution modeling and mapping of. Re effearthradius returns the effective radius, re, of a spherical earth, computed from the gradient of the index of refraction of the atmosphere.
Great circles, geodesics, and useful projections i. If the earth were a perfect sphere without an atmosphere, the radio horizon would be a circle the radio horizon of the transmitting and receiving antennas can be added together to increase the effective communication range. Earth radii uses there is only one radius of a sphere. L1 is inversely proportional to the hydraulic radius rh l. The concept of effective earth as considered in radio and radar communication is seen to be a theoretical value used for the earth radius instead of the actual earth radius.
Find out information about effective radius of the earth. Calculation of effective earth radius and point refractivity. Pdf calculation of effective earth radius and point refractivity. The calculation uses a refractivity gradient of 39e9. Estimation of clearair atmospheric effective earth radius k. Both the factor, which is directly related to the vertical gradient of refractivity, and need to be calculated correctly 1. Sean victor hum radio and microwave wireless systems. Solar power at earth if the earth intercepted all of the suns energy, the oceans would evaporate in 10 seconds. Determination of the effective earth radius factor and its.
For this purpose, the path profile has to be traced with the appropriate equivalent earth radius recommendation itur p. The energy a planet receives per second is the incident flux energy per unit area per second times the projected area of the planet incident flux solar luminosityarea of sphere radius 1 au. Pdf calculation of effective earth radius and point. The physical meaning of effective radius is shown in figure 71. Found 0 sentences matching phrase effective radius of the earth. The reliability of the link is also affected by kfactor values which is usually taken as 43 in regions where there is dearth of data. Radio propagation, microwave radio, refractivity, multipath fading, effective earth radius, kfactor.
The choice of values for link design must be appropriate for the particular topographical setting in order to avoid loss of signal at the receiver 10. Therefore, it is important to determine its average and effective value for. But after many orbits, it eventually sees all of the surface so that a full map can be put together. Pdf effective earth radius factor prediction and mapping. Effective radius of the earth article about effective radius of the earth by the free dictionary. Swaths and coverage 2 when a satellite looks down on the earth from space, it only sees a small part of the surface at a time during each orbit. In this video, i go over the radius of curvature derivation which is very useful for solving curvilinear motion problems in engineering dynamics. A large set of 14 years of reliable local radiosonde meteorological data, from 1990 to 2003, has been used to calculate the effective earth radius and point refractivity gradient in the united. Effective earth radius for refraction of radio waves at. Remote authentication dial in user service radius is a data communications protocol designed to provide security management and statistics collection in remote comput ing environments, especially for distributed networks with dial in users. The refractivity gradient, which depends on the altitude, is the rate of change of refraction index with altitude. A value of 43 has often been used as a standard value, although over the worlds ocean areas the average value is 1. Re denotes earth model radius, here defined to be 6,378 km. Effective earth radius article about effective earth.
Two data modeling methods are used to formulate the solution for the distribution of the effective earth radius factor. A nominal earth radius is sometimes used as a unit of measurement in astronomy and geophysics, denoted in astronomy by the symbol r. In effect, the bending of the beam either up or down makes it appear as though the radius of the earth is less than or greater than the true radius. Effective earth radius kfactor the ratio of the effective earth radius to the actual earth radius is called the k factor. Also, the yearly average value of dn1 and kfactor for lagos are 210. The definition and significance of an effective radius for. When s 0, r we r we2 effective radius is smaller than completion borehole radius, which means a reduction of the borehole radius. Variation of radio refractivity gradient and effective earth radius factor. The kfactor values rise during the wet season with values ranging from 1. Estimation of clearair atmospheric effective earth radius. Thus, in an isotropic environment, rs a2 p, the permeability is given as follows. Effective earth radius article about effective earth radius.
Determination of atmospheric effective earth radius factor k. However, since n is very close to 1, equation 1 is simplified as follows. It is well known that clouds strongly modulate the energy balance of the earth and its atmosphere through their interaction with solar and terrestrial ra. For more information about the computation, see effective earth radius from refractivity gradient.
Oct 16, 20 the propagation loss on a terrestrial lineofsight wireless link is influenced by atmospheric and seasonal conditions. Effective ionic radii in oxides and fluorides, acta crystallographica, b25, 925946, 1969, and revised by shannon in acta. The effective earth radius is a convenient fiction that makes straight the actual curved path of a radio ray in the atmosphere by presenting it relative to an imaginary earth with a radius larger than the radius of the real earth, thus maintaining the relative curvature between earth and radio ray. Accurate prediction and determination of the effective earth radius factor kfactor is critical for optimal performance in the design and planning of terrestrial line of sight communication links. Calculation of effective earth radius and point refractivity gradient. The refraction index for a given altitude is the ratio between the freespace propagation speed and the propagation speed in. Effective radius of the earth article about effective. A32, 751 revised effective ionic radii and systematic. This is referred to as normal refraction or standard atmosphere. Near the earths surface, the radio refractive index gradient dndh is about. Doerry prepared by sandia national laboratories albuquerque, new mexico 87185 and livermore, california 94550 sandia national laboratories is a multiprogram laboratory managed and operated by. The radius of the ffz is 0m a ray and a free space medium is considered. It is important to take into account the curvature of the earth for calculation of lineofsight paths from maps, when a direct visual fix cannot be made. When s 0, r we r w it means actual borehole radius.
Near the earth s surface, the radio refractive index gradient dndh is about. The propagation loss on a terrestrial lineofsight wireless link is influenced by atmospheric and seasonal conditions. Revised effective ionic radii and systematic studies of interatomie distances in halides and chaleogenides by r. We bury the centrifugal force term in the gravity term which we can call effective gravity, and ignore it. The effective earth radius factor k can be used to characterise refractive conditions as normal refraction or standard atmosphere, subrefraction, superrefraction and ducting respectively. As a result, re is approximately 43 of the actual earth radius. Effective earth radius matlab effearthradius mathworks india. See also nonlineofsight propagation for more on impairments in propagation. May 14, 2017 find notespdfs at this feature is not available right now. International journal of multidisciplinary and current. Hence, propagation is possible over a large distance because the rays curve to follow the contour of the earth.
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