Common Control

Physical Units of Parameters

Unit Setting

Defining basic physical units is a prerequisite for simulation. It is important to select proper physical units for different application scenarios. In the software ribbon, click File to display the application menu, users can set the physical units in Setting -> Physical units .

For more information, see Physical Quantities and Units.

Pulse Normalization

Pulse Normalization Setting

In the software ribbon, click File to display the application menu, users can select the desired normalization method in Setting->FDTD pulse normalization .

Name	Descriptions
No normalization	The result data to be returned is the Fourier transform of time-domain pulses.
Continuous wave normalization	Adjust the amplitude or power of pulse signals to a uniform scale.

In the FDTD solver, the FDFP monitor is used to record electric and magnetic fields within various frequency bands defined by the user. Selecting different normalization methods leads to different results to be returned. For example, the pulse signal $s(t)$ is:

$s(t) = sin(\omega_0(t-t_0))exp(-\frac{(t-t_0)^2}{2(\Delta t)^2})$

and the Fourier transform $s(\omega)$ of the time-domain pulse is:

$s(\omega) = \int exp(-i\omega t)s(t)dt$

The frequency-domain field $\boldsymbol{E}{sim}(\omega)$ under No normalization will be:

$\boldsymbol{E}_{sim}(\omega) = \int exp(-i\omega t)\boldsymbol{E}(t)dt$

If the Continuous wave normalization is applied, the frequency-domain field $\boldsymbol{E}_{imp}(\omega)$ will be subject to the normalization process using a frequency-domain pulse signal:

$\boldsymbol{E}_{imp}(\omega) = \frac{\boldsymbol{E}_{sim}(\omega)}{s(\omega)}$

Global Variables

Scope of Global Variables

Global variables are primarily used for importing parameters into input boxes or scripts through expressions. They allow users to modify multiple interlinked parameters in a unified manner, realizing quick and efficient adjustment of simulation projects.
As shown in the figure below, users can directly enter the added global variables in the input box, or click the fx button to view and input the desired global variables in the pop-up page. It is important to note that global variables do not have units, and their physical unit is determined by the input.

In contrast to global variables, the software also offers local variables, such as variables in a script, whose scope is limited to the workspace of the script.

Define Global Variables

Add global variables in the Global variables of the main interface. The four buttons on the right are used to manage global variables, with functions for "Add," "Edit," "Delete," and "Apply" respectively.

Coordinate System

Cartesian Right-Hand Coordinate System

When creating structures in the software, the Cartesian right-hand coordinate system is used.

• For 2D simulation, using the ZX plane;
• For 3D simulation, using the ZXY space.

Coordinate System Transformation

In the Data visualizer window, users can view Line-type images by switching over different coordinate systems to display the result. Currently, the software supports the following coordinate systems:

• xy
  Plot the relationship between one 1D vector and another. For multidimensional matrices, users can select a parameter in the Parameters list as the abscissa, and select a data in the Attributes list as the ordinate.

• Polar
  Plot the angular distribution of parameters. The data to be plotted should include radians and radial axes. The polar coordinates are expressed in degrees.

• Smith chart
  Plot impedance data.

Transmission Phase

For transmission of time-domain pulse, two options are available:

• $exp(-i\omega t)$
• $exp(i\omega t)$

In this software, $exp(-i\omega t)$ represents a phase increase.

Circularly Polarized Light

According to the rotation direction of the light vector, circularly polarized light can be divided into left-handed circularly polarized light and right-handed circularly polarized light.

• If the light vector rotates in the anti-clockwise direction (facing the direction of light propagation), it is left-handed circularly polarized light;
• If the light vector rotates in the clockwise direction (facing the direction of light propagation), it is right-handed circularly polarized light.

Circularly polarized light can be regarded as the synthesis of two plane-polarized lights with same frequency and amplitude, that have the orthogonality in their vibration directions, and a phase difference of $± π/2$. Wherein, the phase difference of $+π/2$ and $-π/2$ corresponds to left-handed circularly polarized light and right-handed circularly polarized light respectively.

As shown in the figure below, the left side is the vector diagram of left-handed polarized light, and the right side is the vector diagram of right-handed circularly polarized light.