This load is set at an arbitrary position inside the FEM mesh, i.e. it is not restricted to tetrahedral edges. The start and end points should coincide with metallic surfaces, but is not required to be at a mesh vertex. The length of the load should be much smaller than the wavelength.

Figure 1: Dialog for addition of a complex load in the FEM region

Consider the cavity backed patch antenna below from [1].

Figure 2: FEKO model for cavity backed patch from [1]

The patch is fed with the FEM current source (AF card) and a 50 Ohm load is placed at the load position using the LF card.

The FEKO result for the input resistance vs. the reference result is shown below.

Figure 3: Comparitive results for input impedance
(a) FEKO (b) Reference result [1] <

One restriction is that this load should not be used as a short due to numerical instability. Users are advised to rather use a metallic strip to make a short.

References