# B4-Attenuation and Scattering

Jump to: navigation, search
Wiki for ITS

## ⌘ Interaction of electromagnetic waves with the Environment

 Interaction with a natural target, here: a tree. The tree will interact with the electromagnetic wave both when it comes to thickness of objects and dimension of objects. Thickness typically influences attenuation, while the dimension of the object contributes to the reflection.

Examples are:

• leaves will mainly interact around 6 Unik/GHz: thickness will attenuate, whereas reflection is due to diameter of leaves
• branches will have main interaction at about 1 Unik/GHz
• the tree trunk will interact with almost all frequencies at 30 Unik/MHz and above.

## ⌘ Attenuation in walls

 Attenuation in material follows typical an exponential behaviour.

## ⌘Attenuation parameters for 2.4 GHz

Obstacle Attenuation $\alpha_i$ [dB]
Brick wall with window 2
Brick wall next to metal door 3
Cinder Block wall 4
Office wall 6
Metal door in office wall 6
Metall door in brick wall 12.4
Floor 30

Measurements performed for European building

(Source:Hydra Deliverable D5.4, p 12)

## ⌘ Path loss calculation

Hydra pass loss approximation
$L = 92,4 + 20 \log(d \mathrm{[km]}) + 20 \log(f \mathrm{[GHz]}) + \sum{n_i \alpha_i}$

• relation between fading margin and receiver sensitivity