ITU Terrain Model

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The ITU Terrain Loss Model is a radio propagation model that provides a method to predict the median path loss for a telecommunication link. Developed on the basis of diffraction theory, this model predicts the path loss as a function of the height of path blockage and the First Fresnel zone for the transmission link.

Contents

[edit] Applicable To / Under Conditions

This model is applicable on any terrain.

This model accounts for obstructions in the middle of the telecommunication link, and therefore, is suitable to be used inside cities as well as in open fields.

This model is ideal for modeling a Line of Sight Link in any terrain.

[edit] Coverage

Frequency: Any

Distance: Any

[edit] Mathematical Formulation

The model is mathematically formulated as:

A \; = \; 10 \; - \; 20 \; C_N

Failed to parse (Cannot write to or create math output directory): C_N \; = \; h \; F_1


h \; = \; h_L \; - \; h_O

F_1 \; = \; 17.3 \; \sqrt{\frac{d_1d_2}{fd}}

Where,

A \; = Empirical Diffraction Loss. Unit: Decibel(dB)

C_N \; = Normalized terrain clearance. Unit: None.

h \; = The height difference. Unit: Meter (m)

h_L \; = Height of the line of sight link. Unit: Meter(m)

h_O \; = Height of the obstruction. Unit:Meter(m)

F_1 \; = Height of First Fresnel Zone. Unit: Meter(m)

d_1 \; = Distance of obstruction from one terminal. Unit: Meter(m)

d_2 \; = Distance of obstruction from the other terminal. Unit: Meter(m)

f \; = Frequency of transmission. Unit: Megahertz(MHz)

d \; = Distance from transmitter to receiver. Unit: Meter (m)

[edit] Limitations

This model is considered valid for losses over 15 dB

This model uses normalized terrain clearance and therefore, is not applicable to terrains where irregularities are high.

[edit] See also

Egli Model

Radio propagation model

Longley-Rice Model