Reference Value and Normalizing

CST PARTICLE STUDIO offer several sources for exciting a given structure, e.g. waveguide ports or plane waves. The common reference signal for these sources is indicated in the Navigation Tree as explained in the Excitation Signal View. This reference signal itself is unitless. The input signals for the different source types are defined as the reference signal mutliplied by a certain fixed or user-defined scaling factor. This scaling factor also carries the specific units of the source types and is described in more detail below. The input signal is given as peak values.

Power View

Amplitude and phase of time domain signals

The scaling factor for the input signal depends on the corresponding excitation type:

Excitation type	Input signal scaling factor
Waveguide port	1 (unit: sqrt(Watt))
Discrete port (S-parameter)	1 (unit: sqrt(Watt))
Discrete port (Voltage)	user defined (unit: V)
Discrete port (Current)	user defined (unit: A)
Field source (RSD current source)	fixed by input data (see broadband imprint normalization)
Field source (FSM and NFD field sources)	fixed by input data (see broadband imprint normalization)

This means that, e.g., a waveguide port realizes an input power of 1 Watt (peak) over its entire port face; therefore, the field amplitude itself changes with the size of the port. In contrast, a Plane wave is excited with a constant field amplitude, independent of the size of the boundary plane where the wave is excited.

Field sources (RSD, FSM, or NFD imports) are excited at the amplitudes given in the input data. No normalization is performed and these field values are fixed by the input data.

Spectral results from transient solvers

All frequency domain results like probes or monitors are in general normalized to the default Gaussian signal to offer comparable results to any solutions from frequency domain solvers. Thus the results correspond to a peak excitation with the input signal scaling factor. For example for a waveguide port excitation, this means 1 Watt stimulated peak power.

Note regarding Particle in Cell (PIC) or Wakefield simulations:
For PIC and Wakefield simulations the normalization is disabled by default. If the frequency based results need to be normalized to the reference signal, the checkbox "Normalize to reference signal" should be enabled: Simulation: Solver Start Simulation Specials Solver.

In case that other signals than the default Gaussian signal are used, then no normalization is applied at all. However, you can still activate normalization to the selected reference signal for the transient solver on the Special Solver Parameters - Solver dialog page.

In case of a transient co-simulation the normalization is by default driven from CST DESIGN STUDIO, i.e. when the co-simulation is excitated with the default Gaussian signal inside CST DESIGN STUDIO then all results inside CST MICROWAVE STUDIO are normalized to this signal. Otherwise the results are unnormalized. This behavior can again be changed by activating normalization to the selected reference signal inside CST MICROWAVE STUDIO for the transient solver on the Special Solver Parameters - Solver dialog page.

Eigenmode solutions

All eigenmode solutions are normalized to 1 Joule total stored energy.