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Optimisation in Feko
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.
Defining an Optimisation Goal
An optimisation goal defines the request type to be optimised and the goal it will attempt to achieve.
Optimisation Goal Types
Select an optimisation goal consistent with the requested output.
Impedance Goal
Optimise the impedance or admittance of a voltage/current source, solved as part of the Feko model.

Welcome
Release Notes
See what's new in the latest release.
Get Started
The Feko Getting Started Guide contains step-by-step instructions on how to get started with Feko.
Examples
The Feko Example Guide contains a collection of examples that teaches you Feko concepts and essentials.
Introduction to Feko
Feko is a comprehensive electromagnetic solver with multiple solution methods that is used for electromagnetic field analyses involving 3D objects of arbitrary shapes.
CADFEKO
CADFEKO is used to create and mesh the geometry or model mesh, specify the solution settings and calculation requests in a graphical environment.
POSTFEKO
POSTFEKO, the Feko post processor, is used to display the model (configuration and mesh), results on graphs and 3D views.
EDITFEKO
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.
Feko Solution Methods
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.
Optimisation in Feko
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.
- Optimisation Workflow in CADFEKO
  The workflow for setting up an optimisation in CADFEKO is explained.
- Launching OPTFEKO (Windows)
  Use the most suitable option for launching OPTFEKO.
- Launching OPTFEKO (Linux)
  Use the most suitable option for launching OPTFEKO in Linux.
- Command Line Arguments for Launching OPTFEKO
  Use the command line arguments to pass additional information to OPTFEKO when it is launched.
- Optimisation Methods and Stopping Criteria
  The duration and accuracy of an optimisation depends on the selected optimisation method and stopping criteria.
- Optimisation Parameters
  Specify the variables to alter during the optimisation run.
- Optimisation Masks
  An optimisation mask is a graphical approach to define an optimisation search. More complex scenarios are handled by a mask, where the goal shape is visually known, for example, the desired bandpass and bandstop regions of a filter.
- Defining an Optimisation Goal
  An optimisation goal defines the request type to be optimised and the goal it will attempt to achieve.
  - Structure of an Optimisation Goal
    Each part of the definition in an optimisation goal serves a specific purpose and should be correctly understood and applied for the desired optimisation outcome.
  - Optimisation Goal Types
    Select an optimisation goal consistent with the requested output.
    - Impedance Goal
      Optimise the impedance or admittance of a voltage/current source, solved as part of the Feko model.
    - Near field Goal
      Optimise the near fields that are solved as part of the Feko model.
    - Far Field Goal
      Optimise the far fields that are solved as part of the Feko model.
    - S-Parameter Goal
      Optimise the S-parameters that are solved as part of the Feko model.
    - SAR Goal
      Optimise the SAR that are solved as part of the Feko model.
    - Power Goal
      Optimise the power that is solved as part of the Feko model.
    - Receiving Antenna Goal
      Optimise the receiving antenna that is solved as part of the Feko model.
    - Transmission / Reflection Goal
      Optimise the transmission and reflection quantities that are solved as part of the Feko model.
  - Focus Processing Options
    Specify what operation should be performed on the selected goal.
  - Goal Operator
    Specify how the focus is compared with the goal objective and the goal operator.
  - Goal Objective
    Choose between a single value or range of values defined by a mask to which the required output is compared with.
- Global Goal: Combining and Weighting of Multiple Goals
  Specify the method for combining multiple goals. A weight or importance factor is assigned to the combined goal and optimised according to the combination type, for example, the average of the goals combined for the specified data.
- Optimisation Using .PRE File modifications
  Use optimisation with modifications made in the .pre file in EDITFEKO.
- Optimisation Solver Settings
  Make adjustments to the optimisation settings for a more computationally efficient solution.
Feko Utilities
The Feko utilities consist of PREFEKO, OPTFEKO, ADAPTFEKO, the Launcher utility, Updater and the crash reporter.
Description of the Output File of Feko
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.
Feko Application Macros
A large collection of application macros are available for CADFEKO and POSTFEKO.
Scripts and Application Programming Interface (API)
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.
Appendix
Reference information is provided in the appendix.

Impedance Goal

Optimise the impedance or admittance of a voltage/current source, solved as part of the Feko model.

On the Request tab, in the Optimisation group, click the

Add Goal Function icon. From the drop down list, select

Impedance goal.

Figure 1. The Create Impedance Optimisation Goal dialog.

The Focus source is identified based on the label of a voltage source or current source in CADFEKO. The Focus source label is identified based on the or a card-defined source, for example, the A1, A2, A3, AF and AN card in EDITFEKO.

Focus Types

The following focus types are available:

Input impedance/Input admittance: Both of these are complex quantities that represent the load characteristics (based on the currents and voltages at the source points). As these focus types always consist of complex values, the focus processing options require that there be at least one general processing step indicating the selection of one of the complex components.
Reflection coefficient (S11): The reflection coefficient is computed with respect to the Reference impedance. For the impedance goal, the reflection coefficient is computed directly from the observed input impedance. This value is then in effect the active reflection coefficient ( $Γ$ ) and may differ from the S11 computed during an S-parameter calculation in a multi-port model.
Transmission coefficient: The transmission coefficient ( $1 - Γ$ ) is considered with respect to the Reference impedance.
VSWR: The voltage standing wave ratio ( $VSWR = \frac{1 + | S_{n n} |}{1 - | S_{n n} |}$ ) for the observed input impedance is considered with respect to the Reference impedance.
Return losses: The return loss ( $- 20 \log | Γ |$ ) for the observed input impedance is considered with respect to the Reference impedance.
Current: The current flowing through the segment on which the selected voltage source is located. In order to use this optimisation goal, a port with a source or an A1 card must be applied to the segment of interest. The source should be set to zero magnitude, and a suitable Source name (label) entered.

Reference Impedance

The impedance to be used during the calculation of the relevant focus types can be specified here. The impedance must be a single non-complex value and is local to each impedance goal (different reference impedances may be used for different impedance goals in the same optimisation search).