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| '''Weissberger’s modified exponential decay model''', or simply, '''Weissberger’s model''', is a [[Radio propagation model|radio wave propagation model]] that estimates the [[path loss]] due to the presence of one or more trees in a point-to-point [[telecommunication]] link. This model belongs to the category Foliage or Vegetation models.
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| ==Applicable to/under conditions==
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| * This model is applicable to the cases of line of sight propagation. Example is microwave transmission.
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| * This model is only applicable when there is an obstruction made by some foliage in the link. i.e. In between the transmitter and receiver.
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| * This model is ideal for application in the situation where the LOS path is blocked by dense, dry and leafy trees.
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| ==Coverage==
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| Frequency: '''230 MHz''' to '''95 GHz'''<ref name = "Ref1">Radio propagation in cellular networks, N. Blaunstein</ref>
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| Depth of Foliage: up to '''400 m'''
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| ==History==
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| Formulated in 1982, this model is a development of the ITU Model for Exponential Decay (MED).
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| ==Mathematical formulation==
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| Weissberger’s model is formally expressed as
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| : <math>L = \begin{cases} 1.33 \, f^{0.284} \, d^{0.588} \,\mbox{, if } 14 < d \le 400 \\ 0.45 \, f^{0.284} \, d \, \, \, \, \, \, \, \, \, \, \mbox{, if } 0 < d \le 14 \end{cases}</math>
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| where,
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| ''L'' = The loss due to foliage. Unit: [[decibel]]s (dB)
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| ''f'' = The transmission frequency. Unit: [[gigahertz]] (GHz)
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| ''d'' = The depth of foliage ‘’’along’’’ the path. Unit: [[meter]]s (m) | |
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| ==Points to note==
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| * The equation is scaled for frequency specified in GHz range.
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| * Depth of foliage must be specified in meters (m).
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| ==Limitations==
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| *This model is significant for frequency range 230 MHz to 95 GHz only, as pointed out by Blaunstein.
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| *This model does not define the operation if the depth of vegetation is more than 400 m.
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| *This model predicts the loss due to foliage. The path loss must be calculated with inclusion of the free space loss.<ref>Introduction to RF propagation, John S. Seybold</ref>
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| ==References==
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| <references/> | |
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| ==Further reading==
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| * ''Introduction to RF Propagation,'' John S. Seybold, 2005, John Wiley and Sons.
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| * ''Radio Propagation in Cellular Networks,'' N. Blaunstein, 2000, Artech House
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| * ''The Mobile Radio Propagation Channel,'' J. D. Parsons, 2000, Wiley
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| * {{cite paper
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| | author = Mark A. Weissberger
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| | title = An initial critical summary of models for predicting the attenuation of radio waves by trees
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| | date = 1982
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| | url =http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA118343
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| | format = [[PDF]]
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| | accessdate = 2012-02-01 }}
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| ==See also==
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| * [[Fresnel zone]]
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| * [[Radio propagation model]]
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| ==External links==
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| [[Category:Radio frequency propagation]]
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