Conformal Surface Current

GEMS conformal technique uses two sets of meshes, the traditional rectangular mesh is used for the field update; and the surface mesh is used for to calculate the conformal surface current distribution on the arbitrary curved surface. A helix antenna array includes 40 helixes, GEMS can calculate the current distribution along the thin helical wire. The surface current distribution is extremely important to analyze the principle of radiation and scattering problems. In all the FDTD based software today, only GEMS can calculate the conformal surface current distribution on a curved surface.

Use the following options to generate the conformal current distribution on the conductor surface:

(1) Draw a geometry or import a structure from CAD file.

(2) Specify the material parameters. The surface current can be only on the good conductor.

(3) Select one or multiple objects in the "Object Browser" box.

(4) Click on the box in the "Properties" box following "Surf-current" and a popup window appears.

(5) Check the "Enabled" box.

(6) Specify the frequency list in which the surface current distributions will be generated during the simulation. Specify the start frequency, end frequency, and frequency step size. Click on the "Generate" button to generate the frequency list.

(7) The default value is "-1" in the "Maximum mesh length of surface", which indicates the cell side length in the surface mesh. The number "-1" means that GEMS uses the default cell size length, which are specified in the "Tools->Set default" option, "Freq level" (number of segments per wavelength for the highest frequency of interest), "Edge level" (one edge includes at least three segments).

If the default mesh is too coarse to describe the surface current distribution, you can input the cell length size in the ""Maximum mesh length of surface" box.

(7) Click on the "OK" button to confirm the settings.

(8) Select the object in the "Object Browser" and then "Tools->Surface Mesh" to show the surface mesh for the selected object. You can select more than one objects at the same time.

If the cell length on the object surface is too small, the display and simulation may take a longer time.


Helix Antenna Array Configuration


Surface Current on Entire Structure


Surface Current on Helix Wire

Single Unit Model


Surface Mesh on Helix Wire



Local Surface Mesh on Helix Wire

Single Helix Configuration


Surface Current at Helix Wire


Surface Current at 3 Frequencies