AF Card

This card defines a uniform electric current filament impressed between two arbitrary points inside of the FEM region (it does not have to coincide with the edges of tetrahedra). This can be used to excite for instance a patch antenna.

On the Source/Load tab, in the Sources on geometry group, click the Current source (AF) icon.

Parameters:

New source: A new excitation is defined which replaces all previously defined excitations.
Add to sources: A new excitation is defined which is added to the previously defined excitations.
Amplitude of source (A): Amplitude in A of the impressed line current.
Phase of source (degrees): Phase of the current in degrees.
X, Y, Z coordinate: Coordinates of the start and end points in m. (Note that all the coordinate values are optionally scaled by the SF card.)
Reference impedance (Ohm): 励振の基準インピーダンスは、Sパラメータの計算用に使用されると共に、得られた利得の計算に使用される基準インピーダンスです。この基準インピーダンスは、POSTFEKO内で反射係数を計算して表示するために使用されるデフォルトの基準インピーダンスでもあります。Sパラメータの計算でこの欄が空白または0の場合は、SPカードで指定された値が使用されます。得られた利得と反射係数の計算でこの欄が空白または0の場合は、50オームが想定されます。

The following restrictions apply when using the impressed current elements of the AF type inside a FEM region:

The electric current source would usually be connected to metallic surfaces at its terminals, but this is neither enforced nor checked in Feko. If a physical connection to a metallic structure is required, then the user should ensure that the feed terminals are also attached in the discretised model.
Input impedance is computed for this source from the line integral over the electric field solution between the terminals of the source. The length of the impressed current should therefore be small compared to the shortest wavelength in the band of interest to render a reasonable accuracy.
An intrinsic limitation of this model is that no radius is taken into account, therefore the field is singular in the vicinity of the filament. This affects the accuracy of the computed input impedance of the source.