AX Cards

These cards define the type of excitation (source) as well as other relevant parameters.

Table 1. Types of excitation and other relevant parameters.
Card Type of Excitation
A0 A linear polarised plane wave incident on the structure.
A1 Excitation by means of a voltage gap on a segment (that is an impressed electric field strength along a segment).
A2 Excitation by means of a voltage gap at a node (that is between two segments).
A3 Excitation by means of a magnetic ring current (TEM-frill) on a segment. Thus a coaxial feed can be modelled.
A5 An electric Hertzian dipole is used as excitation. The position and orientation can be arbitrary.
A6 A magnetic Hertzian dipole is used as excitation. The position and orientation can be arbitrary.
A7 Excitation by means of a voltage gap on an edge between two triangles. It is recommend to rather use the AE card.
AC This card reads the geometry and current distribution (possibly for more than one frequency) from an .rsd file created by a transmission line simulation program (CRIPTE or CableMod) or by a PCB simulation tool (PCBMod) or by export with the OS card in Feko. The excitation is due to the electromagnetic fields radiated by these line currents.
AE The AE card is an excitation between triangle edges similar to the A7 card, however the AE card permits the simultaneous excitation of several edges.
AF Excitation by an impressed line current in the FEM region.
AI Excitation by an impressed line current.
AJ Excitation by means of an impressed current source defined using current data calculated for a PCB.
AK Excitation by means of a voltage source connected to a radiating cable.
AM Excitation by means of an impressed current source defined using model solution coefficients.
AN Excitation by means of a voltage source connected to a non-radiating network port.
AP Excitation by means of equivalent sources in an aperture (array of electrical and magnetic Hertzian dipoles).
AR Excitation by an antenna with a given radiation pattern.
AS Excitation by means of impressed radiating spherical modes.
AT Excitation by means of a voltage source applied to a voxel mesh.
AV Excitation by an impressed line current similar to the AI card, but the end point of the current is electrically connected to a conducting surface.
AW Excitation by an impressed mode on a waveguide port.

The different ways to realise a voltage source are summarised in Figure 1 and Figure 1. The impressed electric field strength is indicated by Ei.



Figure 1. Possible ways to realise a voltage source on a wire segment.


Figure 2. Possible ways to realise a voltage source in connection with triangles.

More than one excitation is also allowed. It is possible, for example, to generate an elliptically polarised plane wave by super-imposing two out-of-phase linearly polarised plane waves with different amplitudes. It is also possible to feed an antenna with two different voltage sources. For this purpose the parameters New source and Add to sources are available in each Ax card. This parameter indicates whether the current excitation is additional (Add to sources) or not (New source). When New source is selected, only the current excitation will be used and the excitations prior to the current one will be erased.

For the excitations A1, A2, A3 and A7 it is possible to select the feed element through the label. Alternatively the position of the feed is specified in Cartesian coordinates. Feko then searches for a segment or an element at this position. This comparison of the position uses the tolerance parameter Maximum identical distance (see the EG Card).