Feko is a comprehensive electromagnetic solver with multiple solution methods that is used for electromagnetic field analyses
involving 3D objects of arbitrary shapes.
EDITFEKO is used to construct advanced models (both the geometry and solution requirements) using a high-level scripting language
which includes loops and conditional statements.
One of the key features in Feko is that it includes a broad set of unique and hybridised solution methods. Effective use of Feko features requires an understanding of the available methods.
Feko offers state-of-the-art optimisation engines based on generic algorithm (GA) and other methods, which can be used
to automatically optimise the design and determine the optimum solution.
Feko writes all the results to an ASCII output file .out as well as a binary output file .bof for usage by POSTFEKO. Use the .out file to obtain additional information about the solution.
CADFEKO and POSTFEKO have a powerful, fast, lightweight scripting language integrated into the application allowing you to create
models, get hold of simulation results and model configuration information as well as manipulation of data and automate
repetitive tasks.
CADFEKO and POSTFEKO have a powerful, fast, lightweight scripting language integrated into the application that allows you to create models,
get hold of simulation results and model configuration information and much more.
Feko integrates into job scheduling and queuing systems such as Altair PBS Professional, Torque, IBM Platform LSF, Parallelnavi NQS, SLURM and Univa Grid Engine.
The MLFMM is an iterative solution method, and under certain conditions, the iterative solution may fail to converge. Several
model or solution settings are presented that could improve the model's convergence behaviour.
The hybrid multilevel fast multipole method (MLFMM) / finite element method (FEM) is an iterative solution method and under certain conditions, the iterative solution may fail to converge.
Several model or solution settings are presented that could improve the model's convergence behaviour.
The hybrid method of moments (MoM) / finite element method (FEM) is an iterative solution method, and under certain conditions, the iterative solution may fail to converge.
Several model or solution settings are presented that could improve the model's convergence behaviour.
The finite difference time domain (FDTD) is a solution method that may fail to converge under certain conditions. Several model or solution settings
are presented that could improve the model's convergence behaviour.
When meshing a model, you can either use the automatic meshing algorithm to calculate the appropriate mesh settings
or you can specify the mesh sizes. When you specify the mesh sizes, the mesh sizes should adhere to certain guidelines.
Feko integrates with various products within Altair HyperWorks Products such as HyperStudy. Integration with third-party products is also supported through the powerful scripting and plug-in infrastructure.
Feko creates and uses many different file types. It is useful to know what is stored in the various files and weather they were
created by Feko and if it is safe to delete them. The files are grouped as either native files that have been created by Feko or non-native files that are supported by Feko. Non-native files are often exported by Feko even if the formats are not under the control of the Feko development team.
How to Interpret Far Fields Calculated from a PBC
Solution
This How-To helps to interpret far-fields (total and scattered) calculated with the
periodic boundary condition (PBC) solution.
For the PBC solution, the default far field is calculated from the solution of a single
unit cell radiating in free space. The PBC unit cell solution is obtained for an
infinite array, meaning all the array element currents/fields are the same.
For a PBC unit cell, consider a truncated patch (derived from the component library) that
radiates left-hand circular (LHC) polarisation.
Consider two cases:
The PBC patch is exited with a voltage source with a specified beam pointing
angle.
The PBC patch is excited with a plane wave, and the port is loaded with 50
Ohm.
Voltage Source Excitation
The PBC solution is obtained by exciting the patch with a voltage to have a beam
pointing angle {theta, phi} = {30, 0} degrees.
Note: The unit cell beam will not
necessarily point to the beam pointing angle.
It is only when requesting the far field1 for a large finite array that the beam pattern will align with
the specified pointing angle.
Plane Wave Excitation
The PBC solution is obtained for two sets of incident plane waves: one with left-hand
circular polarisation (LHC) and another with right-hand circular (RHC) polarisation.
Request the bi-static far field for the unit cell (default) and a 21x21 element
array.
Figure 4 shows the bi-static
RCS pattern for a 21x21 array.
Again, only the unit cell geometry is displayed in the 3D view. The bi-static
RCS includes only the scattered field from the array. It cannot include the
plane-wave field contribution as the plane-wave E-field does not decay with 1/r.
This is the reason for the large forward scatter beam below the array. A large
forward scatter beam is needed to cancel the incident field.
The total near field, which includes the plane wave field contribution, below the
unit cell will be zero. Numerically it will have some finite (but insignificant
small) level due to the discrete nature of the current solution, typically >40 dB
below the incident field level.
The patch array reflects less power when the incident polarisation is matched (LHC),
compared to when the incident polarisation is mismatched (RHC).
This is consistent with the received power in the 50 Ohm load versus incident angle
for LHC and RHC incident polarisation.
More power is received when the incident polarisation (LHC) is matched to
pattern polarisation (LHC) when the patch is excited.
1 Some advanced options are available on
the Request Far Fields dialog
(Advanced tab): option to calculate the far field
from a finite array instead of one unit cell; option to calculate the scattered
field only.