Define the symmetry planes.
This will activate a window containing 3 tabs, one for each kind of symmetry plane. It is possible to check each symmetry plane. Only the checked planes will be taken into account. To simplify the use of this feature, only planes parallel to the axis are considered. For example, the plane OXY contains the origin of the coordinates (O) and is parallel to the X axis and to the Y axis. In other words, it is the plane defined by z=0.
Note : if a symmetry plane is selected, there is no need to create the geometry of the symmetric part. In fact, this must be avoided.
E symmetry
set an electric symmetry plane. An electrical symmetry is a geometrical symmetry, but not only. It also suppose that the electric field is symmetric. The consequence is that it is valid only if the electric field of the source is symmetric. The aim of such a plane is to reduce the size of the problem and thus to increase the speed of the computation.
H symmetry
set an magnetic symmetry plane. Same as the electric field, but with the magnetic field. It is a common way to defined a infinite metallic plane.
The expert's tip :
If you are not sure of your E or H symmetry plane, just compare the results with the complete geometry on a smaller problem, for example at a lower frequency. However, in the case of RCS computation, one of the polarizations (V or H) may be out of the symmetry plane and should be discarded.
Interface between two lossy media :
This plane is slightly different from the previous planes : it is not really a symmetry plane, since it enables to simulate an interface between two infinite half spaces. For a lossy ground plane, two formulations are available : the rigorous Sommerfeld integrals and the approximated Fresnel reflection coefficients. In addition, a medium below the interface must be selected.
A perfect ground plane is equivalent to a magnetic symmetry plane at OXY. There is only one difference : the perfect ground plane is material and not virtual like the magnetic symmetry plane. As a consequence, the radiation pattern below the perfect ground plane will always be zero.
Note : since it is supposed to simulate the ground plane, it is restricted to the OXY plane for clarity purposes.
The expert's tip :
Use the Visualization tool check the defined symmetry planes.
Copyright © 2015, IEEA