Frequency Independent Far Fields

In this case, the file format is simple. No keywords are used. The first two lines contain doubles representing start, stop, and num points for the sweeps of theta and phi. The angle units are degrees. In order to have a unique coordinate system theta and phi should be in the range of 0 < theta < 180 and 0 < phi < 360.

ThetaStart ThetaStop ThetaNumPoints

PhiStart PhiStop PhiNumPoints

Then, the subsequent lines give the complex components of electric far field in the theta and phi directions. By definition, far field is the scattering amplitude of the electric field at the region that is at a large distance from the antenna. Typically the distance must be much greater than 2 D * D / wavelength where D is the largest dimension of radiator or scatterer. The unit of far field is Volt as it is the product of distance and electric field. For these lines, theta will be held constant while phi is swept through all values, then theta will increment to the next value, etc. So the lines will correspond to (th1, ph1), (th1, ph2), (th1, ph3),…,(th1, phN), (th2, ph1), (th2, ph2), etc… Note that this format enforces a strict uniform grid of theta and phi samples.

E_theta_real E_theta_imag E_phi_real E_phi_imag

...

See the following example of a data file:

0,180,3

0,360,5

0.0,0.0,0.0,1.0

Note:

Instead of commas you can use double-space or semicolon separators.