Results and Observables

Result is the object returned by Simulation.run().

Primary fields

Field	Meaning	Public use
state	final solver state / checkpoint payload	inspection, checkpoint export, and debugging; no high-level resume API accepts it as an initial state
time_series	recorded probe values over time	ringdown, transient response, Harminv
s_params	lumped/wire port S-matrix	matching, filters, de-embedding
freqs	frequency axis paired with Result.s_params	lumped/wire S-parameter output; DFT-plane and flux-monitor objects carry their own frequency axes
ntff_data	near-to-far-field accumulation	radiation patterns where documented
dft_planes	frequency-domain plane observables	slices and field maps
flux_monitors	plane flux accumulations	transmission / reflection analysis
waveguide_sparams	per-port waveguide diagnostics	waveguide workflows
snapshots	saved field snapshots	visualization and post-processing
grid	mesh metadata	reproducibility checks
dt	timestep	time-axis conversion

S-parameter result schemas

Calculator	Result object	Public status
run(compute_s_params=True) with lumped/wire add_port(...)	Result.s_params, Result.freqs	documented path for the matching port family
forward(port_s11_freqs=...) with lumped/wire add_port(...)	ForwardResult.s_params, ForwardResult.freqs	differentiable S11 vectors, not a full multi-port matrix
compute_msl_s_matrix(...)	MSLSMatrixResult with .S, .freqs, .Z0, .beta, .port_names, .reliable, .settling_db, .S_raw, .passivity_correction	specialized microstrip-line calculation. .S is passivity-enforced by default (`
compute_waveguide_s_matrix(...)	WaveguideSMatrixResult	rectangular waveguide workflow
compute_coaxial_line_reflection(...)	CoaxialLineReflectionResult	reflection with float32 precision, a nonperiodic 3D second-order uniform Yee grid, CPML on all six boundary faces with positive thickness on both z faces, cpml_axes="z", and exactly one face="top" coaxial port; see Sources and Ports for the self-contained model limits
run(...) with a single waveguide port	Result.waveguide_sparams[name]	diagnostic per-port output

Sources, TFSF, probes, DFT planes, and flux monitors do not automatically define a high-level S-matrix workflow. Coaxial reports should use the documented line-reflection method.

Observable builders that feed Result

Builder	Result field	Typical use
add_probe(...) / add_vector_probe(...)	time_series	transient response, ringdown, local field traces
add_dft_plane_probe(...)	dft_planes	frequency-domain field slices
add_flux_monitor(...)	flux_monitors	reflection / transmission bookkeeping
add_ntff_box(...)	ntff_data, ntff_box	far-field accumulation

Finite-size flux monitors use the same per-cell Poynting integrand as full-plane monitors. When both are summed over the same index window, they agree to machine precision; differences from size=None full-plane monitors are coverage choices, not a separate stability model.

Resonance extraction

Result.find_resonances() runs Harminv-style mode extraction on a probe time series.

result = sim.run(n_steps=8000)
modes = result.find_resonances(freq_range=(1.5e9, 3.5e9))

Use this on a clean probe signal when you want a resonance estimate that is less dependent on port calibration than S-parameters.

Port-observable helpers

rfx.validation provides helper functions for checking S-matrix-like arrays for shape, finite values, frequency metadata, port names, and caller-selected passivity / reciprocity limits.

from rfx import validate_port_smatrix, assert_port_smatrix_valid

report = validate_port_smatrix(result, check_passivity=True, passivity_tol=0.02)
print(report.summary())

These helpers are useful for regression checks. They do not turn an undocumented workflow into the recommended default path.

During normal Python execution outside JAX tracing, some calculation paths emit warnings without changing the arrays. Coverage is deliberately narrow:

• the generic run() warning and uniform single-device forward() warning inspect time_series and lumped/wire s_params, not state, NTFF, DFT-plane, or flux arrays; non-uniform and distributed forward() paths do not invoke this guard;
• lumped/wire run() and uniform single-device forward() check individual entries for non-finite values or |S| > 1.1, but do not test total outgoing column power;
• MSL and waveguide full-matrix calculators apply per-entry and column-power checks with calculator-specific tolerances;
• compute_coaxial_line_reflection() requires float32 precision, a nonperiodic 3D second-order uniform Yee grid, CPML on all six boundary faces with positive thickness on both z faces, cpml_axes="z", and exactly one face="top" coaxial port. It builds its own line, source, probes, and termination and rejects unsupported registered objects. It returns status, fit/recurrence residuals, and s11, but does not run the shared passivity guard. See Sources and Ports before configuring this method.

The ring-down advisory likewise requires a probe time series and is not a direct NTFF or DFT convergence test. Inspect unguarded arrays explicitly. The absence of a warning is not a passivity, convergence, or accuracy result.

For MSL results, reliable[p, k] = False excludes the whole frequency slice S[:, :, k] from physical interpretation — not just the driven-port column — because S is solved jointly across drives (S = B·A⁻¹, #507); the mask covers every driven/port record the solve consumes (#522). A True entry is not an accuracy guarantee. See Probes and S-Parameters for the threshold and filtering example.

Validated observables

For public docs, describe observables in simple terms:

• time_series and Harminv are the recommended resonance path.
• lumped/wire, MSL, waveguide, and coaxial-line S-parameter/reflection workflows each have their own calculator and stated limits.
• NTFF/far-field outputs should be used where the relevant guide documents the workflow.
• Other fields are useful analysis outputs; apply the documented support status for the calculation that produced them.