XFdtd Release 7.5.0

Circuit Element Optimization

Initially designed for matching circuit optimization, the circuit element optimizer (CEO) determines optimal component values while considering a multitude of EM effects on the real circuit's physical layout.

Using XF's full-wave finite-difference time-domain (FDTD) solver, the CEO is able to account for the following EM effects:

• Parasitic and couple effects within the matching network layout.
• Coupling between the matching network and antenna being tuned.
• Coupling between antenna being tuned and other antennas.
• Physical configurations (free space, held in hand, held near head).

The following component types can be optimized:

• Fixed resistor, capacitor, inductor.
• Ideal resistor, capacitor, inductor.
• Realistic capacitor, inductor with user defined equivalent series resistance.
• Passive tunable integrated circuits (tuners).

System efficiency, radiation efficiency, and S-parameters are used as the goal function to determine the final component values.

Electrostatic Solver with Capacitance Matrices

The Electrostatic Solver has been enhanced to increase its accuracy and expand its potential applications.

Improvements within the calculation engine include the following abilities:

• Consider dielectric materials while computing fields.
• Compute charge. Charge is used in capacitance calculations so self- and mutual- capacitance are available in the Spice and Maxwell formulations.
• Handle variable cell sizes in the grid.

The Electrostatic Solver utilizes the XF user interface (UI). New features in the UI allow users to do the following:

• Apply a voltage to individual Parts or an Assembly. A single part with multiple, unconnected bodies can have the same potential.
• View volumetric results for voltage or electric field.

The Electrostatic Solver is available as a stand-alone product or as an add-on to XF.

Time Dependent Material

This new material type allows XF users to specify a material's permittivity and conductivity as a function of time. The inputs can be specified as a constant value, loaded from a file, or entered as an equation. As the timestepping stage of a simulation proceeds through time, the material properties are modified accordingly.

Softkill Termination for Timestepping

An FDTD simulation proceeds through the following stages: initialization, timestepping, steady-state post-processing, and writing output. The softkill feature allows users to terminate the timestepping stage of a simulation and proceed to steady-state post-processing.

Through the UI, terminate timestepping by right-clicking on the simulation in the Simulations window and choosing Stop. Alternatively, create a file named project.softkill in the *.xf/Simulations/### directory to kill a simulation or create the file in .../Simulations/###/Run### to kill the run, but continue the simulation.

Three-Pole Debye-Drude Material on XStream

The graphics processing unit (GPU) kernel has been updated to support dispersive three-pole Debye-Drude material equations rather than supporting only the single-pole representation. This update allows simulations containing the three-pole Debye-Drude material type to utilize the speedups from the GPU hardware. Users can specify the number of GPUs to utilize through the Queue drop-down menu in the Simulations window as they would with non-dispersive materials.