Source Point

open the source point definition window

The source point location is defined with its three coordinates (X,Y,Z). For a real antenna, the source point location is the position of the phase center.

This far field pattern may be moved with 3 rotation angles (around axis X, Y and Z).

In the case of coupling computation, the input impedance of the source is required.

If the source must be close to a surface, the On Surface button must be checked. In that case, the software will try to find the nearest surface.

The free space far field pattern of the point source is described in a file. The format of this file is the same as the output format of IDRA. This file may be generated by another software, or it may build from measurements.

Example (there is only the beginning of the file) :

1.0300000E+09

-180.0000 180.0000 2.000000

0.0000000E+00 135.0000 45.00000

LOCATION ETHETA EPHI gain in dB POLARISATION

THETA PHI magn. phase magn. phase vert. horiz. total axial r. angle direction

-0.1800E+03 0.0000E+00 0.9555E-01 -0.1377E+03 0.0000E+00 0.0000E+00 0.4167E-06 -0.2000E+03 0.0000E+00 0.0000E+00 0.1137E-05 LINEAR

-0.1780E+03 0.0000E+00 0.9549E-01 -0.1377E+03 0.0000E+00 0.0000E+00 -0.5292E-02 -0.2000E+03 -0.5293E-02 0.0000E+00 0.1754E-05 LINEAR

-0.1760E+03 0.0000E+00 0.9531E-01 -0.1377E+03 0.0000E+00 0.0000E+00 -0.2118E-01 -0.2000E+03 -0.2118E-01 0.0000E+00 0.1816E-05 LINEAR

-0.1740E+03 0.0000E+00 0.9502E-01 -0.1377E+03 0.0000E+00 0.0000E+00 -0.4771E-01 -0.2000E+03 -0.4771E-01 0.0000E+00 0.1518E-05 LINEAR

-0.1720E+03 0.0000E+00 0.9462E-01 -0.1377E+03 0.0000E+00 0.0000E+00 -0.8494E-01 -0.2000E+03 -0.8494E-01 0.0000E+00 0.2609E-05 LINEAR

In fact, IDRA doesn't read the entire file. The following items are required :

Operating frequency
θmin θmax θstep (degrees)
ϕmin ϕmax ϕstep (degrees)
2 lines of comments (may be left blank)
For each direction of observation present in the file, IDRA will only read the first 6 columns. The amplitude (Volts) and the phase (degrees) are required.

Remarks :

-180° ≤ θ ≤ 180°
0° ≤ ϕ ≤ 180°
The theta loop is inside the phi loop
The phase reference used to compute the input file must be located at the phase center of the antenna.