What are the specifications while using the wave plane excitation?!

HeLLo!
I would like to know while using a plane wave excitation should I make any specifications other then the direction and polarization such as specifying the origin of the wave. My question rose up when I was using Feko plane wave excitation and the software showed the following figure which seemed to me as if there is a specification on the origin that I don't know. Hope you could help!

Thank You! :grin:

Plane wave source

All other sources will also be considered active during the computations for each plane wave
incident direction.The preview indicates the polarisation of the
E-field (green arrow) and the direction of propagation of the plane wave (blue arrow) for each
of the defined incident directions. Once the field is created, the E-field polarisation is depicted
by a red arrow.
The plane wave source has two modes of operation namely Single incident wave and Loop over
multiple directions.

Single incident wave:

If Single incident wave is selected, a single plane wave is added to the existing
sources. Multiple Single incident wave sources can be added to create specific field distributions.

Loop over multiple directions:

If Loop over multiple directions is selected, FEKO calculates a solution
for each specified direction of incidence. The incident direction is specified in a spherical
coordinate system, in terms of the angles  and  (in degrees). The user must specify
the Start angle, End angle and angle Increment for each angular coordinate. CADFEKO
calculates and displays the resulting number of incident directions.

Polarisation angle: Polarisation angle specifies the angle , in degrees.For elliptical polarisation the Ellipticity
must be larger than 0 (linear polarisation) and smaller than or equal to 1 (circular polarisation).

For detailed explanation you can go through the user manual in FEKO.