# TR Card

This card is used to calculate the transmission and reflection coefficients for a plane wave interacting with a planar structure.

On the Request tab, in the Solution requests group, click the  Transmission / reflection (TR) icon.

## Parameters:

Request name
The name of the request.
X, Y, Z coordinate
Cartesian coordinates of the position of the plane wave in metres. (is scaled by the SF card).
The transmission coefficient is defined as
(1) $\tau =\frac{{E}_{t}}{{E}_{i}}$
The reflection coefficient is defined as
(2) $\rho =\frac{{E}_{r}}{{E}_{i}}$
The figure below shows the incident, transmitted and reflected electric fields on a planar structure.
Note that for a transmission and reflection request, only a single plane wave source is allowed (that is no other sources are allowed in the model). The model should contain either of the following:
• A planar multilayer substrate without any other geometry/mesh in the model
• A 2D periodic boundary condition (PBC).