During simulation EMPIRE XPU continuously evaluates energy and field monitor convergence and terminates the job if accuracy levels have been obtained. The postprocessing is started subsequently for each simulation job.

Smart Signal Processing

Usually for low frequency results it is essential that the time signals are recorded long enough. In order to avoid too long simulation time a smart signal estimation technique is used for the discrete Fourier transformation (DFT).

  • Moving average signal estimation
  • Predicting tail of time signals
  • Adjustable number of sample points (estimation order)

Far Field Processing

Far fields are obtained by recording the near field on a Huygens surface (simulation boundary) and applying a far field transformation during postprocessing. This allows a compact simulation domain which is only a little larger than the radiation source itself.

  • Multi-frequency or broadband recording
  • Arbitrary far field cut angles or 3D radiation patterns
  • Directivity, Gain, Total gain or electric field normaliztaions
  • MIMO envelope correlation coefficient calculation
  • RCS (mono-static) or bi-static scattering cross section analysis

Near field Processing

For analyzing fields in human bodies several averaging methods are defined in compliance standards. A low frequency algorithm can be applied in case of very low frequencies, e.g. coil charging

  • Specific Absorption Rate (SAR) with mass averaging methods
  • Averaged Current Density (ACD) with area averaging
  • Averaged internal electric field (EIAV) with volume averaging
  • Averaged power density (PD) with area averaging

Circuit Simulation

EMPIRE XPU 8.00 features a new circuit simulator with schematic window for the circuitry of EM simulated S-Matrices with circuit elements. Matching circuits or feed networks can therefore be designed without the necessity to run extensive EM simulations.

  • Easy-to-use pick-and-place schematic elements
  • Lumped RLC, couplers, transmission lines or external Touchstone data, e.g. small signal transistor models
  • S-Parameter and Far field result within schematic window

Multi-Port Processing

If multiple ports are excited subsequently a smart postprocessing is used to generate the overall S-matrix. Usually S-Parameter processing assumes a single characteristic impedance which is valid for the complete frequency range. Actually, impedances are frequency dependent and the termination is not ideal in any case. Thus the port properties may influence the S-Parameter results. S-parameters derived from the Y-Matrix reduce the influence of port properties and can improve the symmetry of unequal port types.

  • Creation of admittance matrix Y, impedance matrix Z and scattering matrix S
  • Automatic Touchstone file generation