#### 3.13.3.1. Frequency Dependent Materials

In RF3p simulations, you may define Dielectric materials with frequency dependent properties by entering equations for the Relative Permittivity, Relative Permeability, Electric Loss Tangent, Magnetic Loss Tangent, Electric Bulk Conductivity, and Magnetic Bulk Conductivity. For details on using equations, see “Solver Integrated Functions”. Define frequency-dependent equations according to the following rules:

• The only variable that may be used in the equation is _FREQ. _FREQ has units of Hz. It is automatically set to the simulation frequency during run time.

• Only global constants _PI and other constants defined using the built-in function constants() are supported.

• Built-in math functions are supported.

• Equations must be real. Complex equations are not supported, and the imaginary numbers "i" and "j" are not recognized.

In order to simplify complex equations, the following functions are available as well:

Function

Description

rePole(reA,imA,reB,imB)

Real part of (1/(A+B)) where A and B are complex numbers and reA and reB are the real parts of A and B respectively, and imA and imB are the imaginary parts of A and B respectively.

imPole(reA,imA,reB,imB)

Imaginary part of (1/(A+B)) where A and B are complex numbers and reA and reB are the real parts of A and B respectively, and imA and imB are the imaginary parts of A and B respectively.

reLog(reA,imA)

Real part of the natural logarithm of A where A is a complex number and reA is the real part of A and imA is the imaginary part of A.

imLog(reA,imA)

Imaginary part of the natural logarithm of A where A is a complex number and reA is the real part of A and imA is the imaginary part of A.

To specify a frequency-dependent material parameter, enter the frequency-dependent equation in the parameter field in the property grid. For example, you may enter the following for the Relative Permittivity: freq_dep('3.8+0.05*(reLog(1.6e11,_FREQ)-reLog(1.6,_FREQ))').

After the simulation, the log includes a path to a text file where the calculated values for the frequency-dependent properties are given over the simulation frequency range. It is recommended that you examine the contents of this file to verify that the properties are as expected. This will allow you to catch input errors in the frequency-dependent materials. The file is output to the model directory. To easily navigate to this directory, from the Home ribbon in the Utilities group, click on the Show Files & Folders button. Your Model Directory is listed in the Current Model section of the dialog box.