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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. | |||
==Applicable to/under conditions== | |||
* This model is applicable to the cases of line of sight propagation. Example is microwave transmission. | |||
* 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. | |||
* This model is ideal for application in the situation where the LOS path is blocked by dense, dry and leafy trees. | |||
==Coverage== | |||
Frequency: '''230 MHz''' to '''95 GHz'''<ref name = "Ref1">Radio propagation in cellular networks, N. Blaunstein</ref> | |||
Depth of Foliage: up to '''400 m''' | |||
==History== | |||
Formulated in 1982, this model is a development of the ITU Model for Exponential Decay (MED). | |||
==Mathematical formulation== | |||
Weissberger’s model is formally expressed as | |||
: <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> | |||
where, | |||
''L'' = The loss due to foliage. Unit: [[decibel]]s (dB) | |||
''f'' = The transmission frequency. Unit: [[gigahertz]] (GHz) | |||
''d'' = The depth of foliage ‘’’along’’’ the path. Unit: [[meter]]s (m) | |||
==Points to note== | |||
* The equation is scaled for frequency specified in GHz range. | |||
* Depth of foliage must be specified in meters (m). | |||
==Limitations== | |||
*This model is significant for frequency range 230 MHz to 95 GHz only, as pointed out by Blaunstein. | |||
*This model does not define the operation if the depth of vegetation is more than 400 m. | |||
*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> | |||
==References== | |||
<references/> | |||
==Further reading== | |||
* ''Introduction to RF Propagation,'' John S. Seybold, 2005, John Wiley and Sons. | |||
* ''Radio Propagation in Cellular Networks,'' N. Blaunstein, 2000, Artech House | |||
* ''The Mobile Radio Propagation Channel,'' J. D. Parsons, 2000, Wiley | |||
* {{cite paper | |||
| author = Mark A. Weissberger | |||
| title = An initial critical summary of models for predicting the attenuation of radio waves by trees | |||
| date = 1982 | |||
| url =http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA118343 | |||
| format = [[PDF]] | |||
| accessdate = 2012-02-01 }} | |||
==See also== | |||
* [[Fresnel zone]] | |||
* [[Radio propagation model]] | |||
==External links== | |||
[[Category:Radio frequency propagation]] | |||
Revision as of 13:44, 9 November 2013
Weissberger’s modified exponential decay model, or simply, Weissberger’s model, is a 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.
Applicable to/under conditions
- This model is applicable to the cases of line of sight propagation. Example is microwave transmission.
- 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.
- This model is ideal for application in the situation where the LOS path is blocked by dense, dry and leafy trees.
Coverage
Frequency: 230 MHz to 95 GHz[1]
Depth of Foliage: up to 400 m
History
Formulated in 1982, this model is a development of the ITU Model for Exponential Decay (MED).
Mathematical formulation
Weissberger’s model is formally expressed as
where,
L = The loss due to foliage. Unit: decibels (dB)
f = The transmission frequency. Unit: gigahertz (GHz)
d = The depth of foliage ‘’’along’’’ the path. Unit: meters (m)
Points to note
- The equation is scaled for frequency specified in GHz range.
- Depth of foliage must be specified in meters (m).
Limitations
- This model is significant for frequency range 230 MHz to 95 GHz only, as pointed out by Blaunstein.
- This model does not define the operation if the depth of vegetation is more than 400 m.
- This model predicts the loss due to foliage. The path loss must be calculated with inclusion of the free space loss.[2]
References
Further reading
- Introduction to RF Propagation, John S. Seybold, 2005, John Wiley and Sons.
- Radio Propagation in Cellular Networks, N. Blaunstein, 2000, Artech House
- The Mobile Radio Propagation Channel, J. D. Parsons, 2000, Wiley
- Template:Cite paper