# Electric / Magnetic Near Fields (.EFE / .HFE)

The data structure for the .efe and .hfe files are described.

The following fields are available in the header block:

Table 1. Fields in the header block of the .efe and .hfe files.
Key Required Description
File Type Yes Describes the type of the file. The file type can be any of the following:
• Electric Near Field
• Magnetic Near Field
File Format Yes Denotes the file syntax version (such a “4”). If not present, it defaults to version 1 (files pre-dating Feko 6.1).
Source Optional Denotes the base filename of the source where this data comes from.
Date Optional Date and time of data export in format “YYYY-MM-DD hh:mm:ss” (that is 24-hour format)

The following fields are available in the solution block header:

Table 2. Available fields in the solution block header of the .efe and .hfe files.
Key Required Description
Configuration Name Optional The configuration name, if present.
Request Name Optional The explicit name given to that solution request (as denoted in the .pre file). If none is specified, POSTFEKO uses a default name of request_N (where _N is replaced with a number for each unnamed request) during import.
Frequency Yes Frequency in Hz for which the following data was measured/computed.
Coordinate System Optional Coordinate system in which the axes are defined:
• Cartesian (default)
• Cylindrical
• Spherical
• Cylindrical (X axis)
• Cylindrical (Y axis)
• Conical
• Cartesian Boundary
Origin Optional Origin of the data coordinate system in form (x, y, z) (always in Cartesian coordinates; based on global origin). If no origin is provided, assume (x, y, z) = (0, 0, 0).
U-Vector Optional Indicates a point on the U axis relative to the Origin. If none is specified, it is assumed that the U axis coincides with the X axis.
V-Vector Optional Indicates a point on the V axis relative to the origin. If none is specified, it is assumed that the V axis coincides with the Y axis.
No. of [$$] Samples Yes The number of samples in each axis direction. The “[$$$]” term is replaced by the following: • X/U • Y/V • Z/N • Phi • Theta • Rho • Radius • Cuboid Result Type Optional For electric near fields (.efe), this specifies whether the output is one of the following: • Electric Field Values (default) • Magnetic Vector Potential • Gradient of Scalar Electric Potential • Electric Scalar Potential For magnetic near fields (.hfe), this specifies whether the output is one of the following: • Magnetic Field Values (default) • Electric Vector Potential • Gradient of Scalar Magnetic Potential • Magnetic Scalar Potential Excluded Faces Key Only applicable to Cartesian near field boundary request. Specify an integer that is a bit-wise interpretation of the following: • 0: Default - All faces included • 1: +N face excluded • 2: -N face excluded • 4: -V face excluded • 8: +V face excluded • 16: -U face excluded • 32: +U face excluded Spatial Units Optional Specify the units in which the position is defined. Result Units Optional Specify the units in which the results are given. No. of Header Lines Optional Number of header lines to read. The column header lines must follow this line. If this value is not specified, assume a value of “1”. Yes For header lines, the following format should be used: #No. of Header Lines: M #"Column 1: Line 1" "Column 2: Line 1" ... "Column N: Line 1" #"Column 1: Line 2" "Column 2: Line 2" ... "Column N: Line 2" ... #"Column 1: Line M" "Column 2: Line M" ... "Column N: Line M" The default column headers all have the same structure. The column headers depend on the coordinate system that was defined, which can be found in the Coordinate System value. For each column, the text “$$” will be replaced with the appropriate value depending on the Result Type. The column headers for each coordinate system follows below. Cartesian [vector]: X Y Z Re($$$x) Im($$x) Re($$$y) Im($$y) Re($$$z) Im($$z) Cartesian [scalar]: X Y Z Re($$$) Im($$) Cylindrical (X axis) [vector]: Rho Phi X Re($$$rho) Im($$rho) Re($$$phi) Im($$phi) Re($$$x) Im($$x) Cylindrical (X axis) [scalar]: Rho Phi X Re($$$) Im($$) Cylindrical (Y axis) [vector]: Rho Phi Y Re($$$rho) Im($$rho) Re($$$phi) Im($$phi) Re($$$y) Im($$y) Cylindrical (Y axis) [scalar] Rho Phi Y Re($$$) Im($$) Cylindrical [vector]: Rho Phi Z Re($$$rho) Im($$rho) Re($$$phi) Im($$phi) Re($$$z) Im($$z) Cylindrical [scalar]: Rho Phi Z Re($$$) Im($$) Spherical [vector]: Radius Theta Phi Re($$$r) Im($$r) Re($$$theta) Im($$theta) Re($$$phi) Im($$phi) Spherical [scalar]: Radius Theta Phi Re($$$) Im($$) Conical [vector]: Rho Phi Z Re($$$rho) Im($$rho) Re($$$phi) Im($$phi) Re($$$z) Im($$z) Conical [scalar]: Rho Phi Z Re($$$) Im($$) Note: All of the coordinate system descriptions contain a section of text, “$$$”. This text is not meant to be included in the file, but rather to serve as a place holder.
The contents of the “$$” place holder will depend on the type of data being presented and the type of file being written. For any of the above systems, replace “$$$” with any of the following: Table 3. Fields to replace “$$” with in the .efe files: .efe Electric Near Field Files E for electric field values A for magnetic vector potential values grad(PHI) for gradient of the scalar electric potential values PHI for scalar electric potential values Table 4. Fields to replace “$$$” with in the .hfe files:
.hfe Magnetic Near Field Files
H for magnetic field values
F for electric vector potential values
PSI for scalar magnetic potential values

## Cartesian Near Field Boundary

The sampling order is as follows for a Cartesian near field boundary request:

Xmin → Xmax → Ymin → Ymax → Zmin → Zmax

An example of a simplified file, with two samples in each dimension, and the Zmin face excluded from the request:
...
#Coordinate System: Cartesian Boundary
...
#Excluded Faces Key: 1
...
#  "X"  "Y"  "Z"  ...
0    0    0   ... ** X_min
0    1    0   ...
0    0    1   ...
0    1    1   ...
1    0    0   ... ** X_max
1    1    0   ...
1    0    1   ...
1    1    1   ...
0    0    0   ... ** Y_min
1    0    0   ...
0    0    1   ...
1    0    1   ...
0    1    0   ... ** Y_max
1    1    0   ...
0    1    1   ...
1    1    1   ...
0    0    0   ... ** Z_min
1    0    0   ...
0    1    0   ...
1    1    0   ...