# Advanced Settings for Far Field Requests

Use advanced settings to specify the currents or subset thereof to be taken into account for the calculation of fields, the export of far field data, ignoring the radiated contribution from impressed sources, calculating spherical modes and calculating the far field for an array of elements.

On the Request tab, in the Solution Requests group, click the  Far Fields icon. The advanced settings are available on the Scope tab and Advanced tab.

## Specify the Currents Taken Into Account During Field Calculation

Field calculation using all sources
With this option, the currents on all structures are taken into account when calculating the far field result (default).
Field calculation using only sources on elements with specified labels
With this option, only the currents on structures with specified labels are taken into account when calculating the far field result.

## Export Directivity or Gain

This setting controls what is written to file (either directivity or gain).
Directivity
This option writes out the directivity to the selected output files (.out and .ffe file).
Gain
This option writes out the gain to the selected output files (.out and .ffe file).

## Export Far Field Data

Export fields to ASCII file (*.ffe)
This option exports the far fields to a .ffe file. Use this file for further post-processing or, when using spherical coordinates, as source pattern for a radiation pattern point source or a receiving antenna.
Export fields to *.out file
This option exports the fields to the .out file.
Only determine radiated far field power by integration
This option calculates the far fields and the total radiated power but the field values are not written to the .bof or .out output files.
Tip: Use this option if the individual field values are not required and the output files would otherwise become too large. Far field values will not be available for viewing in POSTFEKO or for optimisation in OPTFEKO.

## Far Field Interpolation

Calculate continuous far field data
This option uses interpolation to display far field data in POSTFEKO.

## Ignore Radiated Contribution from Impressed Sources

Calculate only the scattered part of the field
This option ignores the radiated contribution from impressed sources (for example, electric point source, magnetic point source) as well as contribution from plane wave sources, yielding only the scattered fields.
Note: The default setting is recommended.

## Spherical Mode Options

Calculate spherical expansion mode coefficients
This option calculates the coefficients and exports the data to a .sph (TICRA) file.
Note: Set the radiated power in Feko to 4 $\pi$ Watts to ensure the gain in GRASP will be correct.
Specify number of modes
This option allows you to specify the maximum mode index. If no value is specified, the maximum mode index is calculated automatically.
Maximum mode index N
Specify the maximum mode index.
Export spherical expansion coefficients to ASCII file
This option exports the spherical expansion mode coefficients to an ASCII file.

## Periodic Boundary Condition Options

Calculate far field for an array of elements
This option allows the far field to be calculated for an array of elements.