Weissberger's model

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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[edit]

  • 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[edit]

Frequency: 230 MHz to 95 GHz[1]

Depth of Foliage: up to 400 m

History[edit]

Formulated in 1982, this model is a development of the ITU Model for Exponential Decay (MED).

Mathematical formulation[edit]

Weissberger’s model is formally expressed as

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}

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[edit]

  • The equation is scaled for frequency specified in GHz range.
  • Depth of foliage must be specified in meters (m).

Limitations[edit]

  • 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[edit]

  1. ^ Radio propagation in cellular networks, N. Blaunstein
  2. ^ Introduction to RF propagation, John S. Seybold

Further reading[edit]

See also[edit]

External links[edit]