mpylab.tools.vna_data module

Read VNA traces and serialize phase-preserving, power-scaled DAT data.

class mpylab.tools.vna_data.Trace(frequency: object, db: object, phase: object, parameter: str, reference: tuple = ())

Bases: object

One VNA trace, with frequencies in Hz, magnitude in dB and phase in degrees.

Parameters:

  • frequency (array-like) – Strictly increasing, finite, nonnegative frequencies.

  • db (array-like) – Finite magnitude and phase arrays of the same length.

  • phase (array-like) – Finite magnitude and phase arrays of the same length.

  • parameter (str) – Trace name or S-parameter identifier.

  • reference (tuple of float, optional) – Touchstone reference resistances in ohms, one per port.

db: object
frequency: object
parameter: str
phase: object
reference: tuple = ()
mpylab.tools.vna_data.detect_sweep(frequencies, *, rtol=1e-05)

Classify frequency spacing without resampling.

Parameters:

  • frequencies (array-like) – Strictly increasing, finite, nonnegative frequencies in Hz.

  • rtol (float, optional) – Relative spacing tolerance, default 1e-5.

Returns:

linear, log, irregular or ambiguous.

Return type:

str

Raises:

ValueError – If the frequencies or tolerance are invalid.

mpylab.tools.vna_data.read_csv(path, *, parameter=None, delimiter=None, columns=None, frequency_unit=None, skip_rows=0)

Read a VNA CSV with named dB/angle columns or explicit column indices.

Parameters:

  • path (path-like) – UTF-8 CSV file (an optional BOM is accepted).

  • parameter (str, optional) – S-parameter to select, or all. Ambiguous traces require selection.

  • delimiter (str, optional) – Single-character CSV separator; by default detect comma, semicolon or tab.

  • columns (tuple of int, optional) – Zero-based frequency, dB and phase column indices. Bypasses header discovery.

  • frequency_unit (str, optional) – Hz, kHz, MHz or GHz. Required with explicit columns.

  • skip_rows (int, optional) – Number of initial physical lines to skip.

Returns:

Selected traces in file order.

Return type:

list of Trace

Raises:

  • ValueError – If headers, numeric records or the frequency axis are invalid.

  • OSError – If the source cannot be read.

mpylab.tools.vna_data.read_touchstone(path, *, parameter=None)

Read one- or two-port single-ended Touchstone S data.

Parameters:

  • path (path-like) – .s1p, .s2p or Touchstone 2.0 .ts source.

  • parameter (str, optional) – Sij to extract, or all. Two-port files require explicit selection.

Returns:

Traces with unchanged reference resistances. No renormalization occurs.

Return type:

list of Trace

Raises:

  • ValueError – If malformed or unsupported, including noise data, mixed mode, zero magnitude, non-full matrices, or port counts other than one and two.

  • OSError – If the source cannot be read.

Notes

The supported 2.0 subset requires Version, Number of Ports, Number of Frequencies, Network Data and End; two-port data also needs Two-Port Data Order. Unknown keywords are rejected, not silently ignored.

mpylab.tools.vna_data.render_dat(trace, *, source='', magnitude_error_db=0.2, phase_error_deg=1.0, sweep_rtol=1e-05)

Render validated polar dB DAT text, preserving the input frequency grid.

Parameters:

  • trace (Trace) – VNA values to serialize.

  • source (str, optional) – Source label recorded in a comment.

  • magnitude_error_db (float, optional) – Symmetric dB half-span, default 0.2.

  • phase_error_deg (float, optional) – Phase standard uncertainty, default 1 degree, strictly below 180.

  • sweep_rtol (float, optional) – Relative tolerance used for the sweep classification comment.

Returns:

DAT text with explicit lower, nominal and upper polar values.

Return type:

str

Raises:

ValueError – If errors or values cannot be represented by the DAT uncertainty model.

Notes

The reader uses half the linearized magnitude span as its standard uncertainty. Magnitude and phase uncertainties are independent; no frequency-to-frequency correlations are inferred.