Electromagnetic Field Assessment in Urban Zone with Hierarchic Description and  Homogeneisation Process




Main topic
Homogeneization process in urban zone

What is the Predominant Radiating Zone PRZ or  the "active" zone ?
Reflexion on a inhomogeneous building:
    - Simple or double glazing
    - open, closed, shutter
  Doors: wood, metal,  glass …

 Reflexion's coefficient depends on:
       - the materials around the specular reflexion's point
                       => homogeneization
       - the zone of reception
                       => dynamical approach
PRZ: zone where 90% of the energy received by the surface has come from 

Homogeneization's process
Step 1
Step 2
Step 3
Step 4
Initial diffracting profile
dark zone =  concrete
light zone = glass
Computation of the predominant radiating zone (the PRZ contributes up to 90% of the reflected energy)
Computation of the equivalent material inside the PRZ
Application of the equivalent material on all the surface

Implementation of a dynamical homogeneization on a simple test case
Description of the scene
Reflected electric field without homogeneization
Reflected electric field with homogeneization
A plate made of two different materials (one pink and the other one yellow) is illuminated by a plane wave with a vertical incidence.
The reflected electric field is computed by the classical specular reflexion. A discontinuity appears between the two different materials.
In this case, the reflected field is computed by using the homogeneization in the PRZ.

The homogeneization enables to take into account more accurately  the reflexion than just the specular reflexion. The discontinuity has disappeared.
in green:
the grid of receivers

in rose:
first material
epsilon =2+10i

in yellow:
second material epsilon =10+100i

Computation and measurement of the RCS applicated to the prediction of electromagnetic field in urban environment
Experimental setup to measure the RCS of a metallic plate
Application to the prediction of EM field in urban environment

Experimental setup installed at the university of Paris Est Marne-la-vallée.

If the receiver is enough far from the buildings, these buildings will be remplacer by their equivalent  RCS.

Measurements vs analytical computations

Computation of the electric field from equivalent RCS of different buildings blocks