Smith Chart Calculator

Smith Chart — RF impedance matching workspace: interactive chart + auto-match + network steps + S-param overlays.

Supported and not supported

Supported — SVG constant-r/x · series/shunt L·C·R · transformer · parallel RLC · auto-match (L-section · single stub · λ/4) · drag ZL / looking-in · tune slider · hover Z/Γ · VSWR/Q circles · named markers · Custom Z(f) · f-locus · Touchstone S11/S21 · stability/gain/noise circles · URL state (smith_state) · API modes z-gamma | gamma-z | match | match-steps | s11-touchstone | auto-match

Not supported — multi-section Chebyshev / broadband optimizers · full bilateral gain circles with S12 feedback redesign

Agent / API notes

Capability id: electrical.rf.smith · tool id: smith-chart · pin 1.6.3.

CVP (Proposed 1.0, engineering) verifies Γ↔z (z-gamma, gamma-z, invalid-domain, round-trip, metamorphic: conjugate-z, lossless |Γ|, two 90° tlines, ωL and R/Z0 scale), looking-in match-steps (series-X/R, lumped L·C, lossless tline, open/short stub, transformer, parallel-RLC), auto-match (Pozar L-section, λ/4, and single-stub; residual |z_in−1|₂, keep <0.08, matched <0.02; each candidate independently re-substituted on looking-in O2 with L/C/R>0; includes 2.44 GHz z=2+j1 shunt-C/series-L and shunt-L/series-C), Touchstone 1.x S11 (s11-touchstone: MA/RI/DB, Hz–GHz, last-point Γ→z), numerical f-sweep of looking-in (span_frac around f0; same model as Analyze f-locus), Custom Z(f) linear interpolation of normalized load at the query frequency (frozen load; same model as Analyze “Use custom Z(f) as load”), numerical 2-port S21 + Rollett K/μ (last .s2p row; same model as Analyze S21/K readout; includes K≈1 and |Δ|≈1), Gonzalez load/source stability-circle geometry (centre + radius, plus origin/inside stable-side flags; den=0 → ∞ sentinels), canonical Γ→chart XY (default SVG viewport size=520, pad=28; same affine map as UI toPx, including f-sweep locus points) and default-viewport SVG load/Zin marker px from buildSmithChartSvg at size=520/640, unilateral GTU Gs/Gl circles at absolute −1/−3 dB (|S11|=1 omits Gs), and constant-NF circles at NFmin+0.5 / NFmin+1 dB from the last Touchstone 1.x noise row (rn=0 and missing noise omit circles), with an mpmath O3 table for tabulated Γ↔z vectors (library, dps, backend, rounding, and generator SHA-256 recorded). |Γ|=1 uses VSWR=+∞ and RL=0; |Γ|≥0.99 but <1 compares VSWR/RL at relative error ≤1e-12 (not skipped). A Node URL-query contract (ohm↔norm conversion that preserves Z, visible R/X beating hidden z_r/z_i, illegal smith_state, Basic/Match/Analyze tier) is exercised as properties — not a live browser session. Cross-calculator consistency (CVP-XCAL-01) compares Γ↔z / VSWR / overlapping real-RL L-section against the related Γ↔z, VSWR, and LC Match tools; complex-z auto-match vs LC Match is N/A (real RL↔Z0 only). Verification revision 2026-09-07.p14 identifies this CVP batch under calculation version 1.6.3. REST/MCP responses bind calculation_version, verification_revision, verified_scope, and evidence_digest so an Agent can attach a specific result to this evidence batch. Per-sample Z(f) re-interpolation during f-sweep, live CSS-resized SVG, grid/path d= markup, stability/gain/noise overlay drawing, drag/hover, history, bilateral MAG/MSG, 3 dB bandwidth, and interactive workspace features are outside this CVP scope.

UI workspace tiers: Basic (Z↔Γ) · Match (lumped / distributed / transformer + auto-match) · Analyze (f-locus, circles, Z(f), Touchstone). SEO H1 remains “Smith Chart Calculator”; product label is “RF Smith Chart & Matching Workspace”.

Input schema is mode-discriminated (oneOf): each mode lists its own required fields. match-steps.steps[] items require kind plus the fields for that kind (e.g. series-L → L_H).

Touchstone support matrix

Reference specification: Touchstone 2.1 (IBIS Open Forum). Currently implemented parser: Touchstone 1.x subset (2.0 / 2.1 keyword / option-line sections are rejected).

Parser / Agent error codes: TOUCHSTONE_MISSING_PARAMETER · TOUCHSTONE_INVALID_HEADER · TOUCHSTONE_UNSUPPORTED_FORMAT · TOUCHSTONE_INVALID_POINT.

auto-match example:

{
  "mode": "auto-match",
  "Z0_ohm": 50,
  "f_Hz": 1e9,
  "z_r": 2,
  "z_i": 1,
  "topology": "all"
}

match-steps example (series R + transformer):

{
  "mode": "match-steps",
  "Z0_ohm": 50,
  "f_Hz": 1e9,
  "z_r": 2,
  "z_i": 1,
  "steps": [
    { "kind": "series-R", "R_ohm": 10 },
    { "kind": "transformer", "n": 2 }
  ]
}

s11-touchstone example:

{
  "mode": "s11-touchstone",
  "touchstone": "# Hz S MA R 50\n1e9 0.333 0\n2e9 0.2 30"
}