# Reflection Loss

The field strength
$\underset{\_}{{E}_{r}}$
of the reflected wave is computed using the reflection
factor
$\underset{\_}{{R}_{12}}$
and the field strength
$\underset{\_}{{E}_{i}}$
of the incident wave^{1}:

$$\frac{{E}_{r}}{{E}_{i}}=\left|{\underset{\_}{{R}_{12}}}^{\text{'}}\right|$$

The reflection factor $\underset{\_}{\left|{\underset{\_}{{R}_{12}}}^{\text{'}}\right|}$ is computed from the transmission factor $\underset{\_}{\left|{T}_{12}\right|}$ :

$$\left|{\underset{\_}{{R}_{12}}}^{\text{'}}\right|=1-\left|\underset{\_}{{T}_{12}}\right|$$

Additionally, the roughness is considered by:

$$\left|\underset{\_}{{R}_{12}}\right|=\left|{\underset{\_}{{R}_{12}}}^{\text{'}}\right|\cdot {\rho}_{0}$$

A smooth surface has a value of
${\rho}_{0}=1.0$
.

Note: In the case of a rough surface, the (higher)
reflection loss is computed via the Bidirectional Reflectance Distribution Function (BRDF).

The value of $\left|{R}_{12}\right|$ is shown in column L in the table.

The reflection loss is then computed as follows:

$${L}_{R}=20\cdot \mathrm{log}\left|\underset{\_}{{R}_{12}}\right|$$

^{1}G. Wölfle: Adaptive Modelle für die Funknetzplanung und zur Berechnung der Empfangsqualität in Gebäuden. (Adaptive Propagation Models for the Planning of Wireless Communication Networks and for the Computation of the Reception Quality inside Buildings). PhD Thesis, University of Stuttgart, published by Shaker Verlag, 2000.