# Transmission / Reflection Coefficients (.TR)

The data structure for the .tr files are described to understand and correctly post-process these files externally.

The following fields are available in the header block:

Table 1. Fields in the header block of the .tr file.
Key Required Description
File Type Yes Describes the type of the file. For a transmitted and reflected wave, the value must be Transmission Reflection Coefficient.
File Format Yes Denotes the file syntax version (such as “5”). 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 .tr file.
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 will use 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.
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.
Polarisation Type Yes Indicates the polarization type, for example, linear, elliptical, circular.
Reference Plane Position Optional The reference plane position for the phase reference of a transmission / reflection request. If none is provided, assume “(x, y, z)” = “(0, 0, 0)”.
Lattice Vector Origin Yes (with PBC) Periodic boundary condition lattice vector starting point in the form “(x, y, z)” (always in Cartesian coordinates; based on global origin). The field is required for periodic boundary condition files, but may be omitted when a file is created using planar substrates.
Lattice Vector U1 Yes (with PBC) Periodic boundary condition lattice vector U1 in the form “(x, y, z)” (always in Cartesian coordinates; based on global origin). The field is required for periodic boundary condition files, but may be omitted when a file is created using planar substrates.
Lattice Vector U2 Yes (with PBC) Periodic boundary condition lattice vector U2 in the form “(x, y, z)” (always in Cartesian coordinates; based on global origin). The field is required for periodic boundary condition files, but may be omitted when a file is created using planar substrates.
No. of [$$] Samples Yes The number of samples in each axis direction. The “[$$\$]” term is replaced by the following:
• Incident Theta
• Incident Phi
• Polarisation Angle
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 column headers for transmission / reflection coefficients when surface characterisation is being performed.
Characterised surface format:
Incident Theta  Incident Phi  Polarisation Angle ...
... Re(R_CrossPol) Im(R_CrossPol) Re(R_CoPol) Im(R_CoPol) ...
... Re(T_CrossPol) Im(T_CrossPol) Re(T_CoPol) Im(T_CoPol)