Transmission Line / SWR Calculator mechanism

Model scope

The reflection-coefficient, VSWR, and return-loss formulas are standard under the stated real-positive-Z0 assumptions. The instrument cannot pass as specified because mismatch loss is claimed but not defined, and the power-input mode overclaims a complex reflection coefficient without phase information.

• The listed formulas omit mismatch loss, although mismatch loss is claimed as an output. The standard passive-load formula is ML=-10log10(1-|Γ|^2) dB, equivalently -10log10(P_transmitted/P_incident).
• The forward/reflected-power input path determines only |Γ|=sqrt(Pr/Pf); it cannot determine the complex reflection coefficient Γ without a reflection phase input.
• VSWR=(1+|Γ|)/(1-|Γ|) is valid for |Γ|<1. At |Γ|=1 it is infinite, and for |Γ|>1 it is not a physically valid passive-load VSWR result.
• The reflection-coefficient formula assumes a real, positive characteristic impedance Z0. If a complex reference impedance is intended, the reference-conjugation convention must be specified.
• Return loss is undefined/infinite at Γ=0 and requires an explicit UI/output convention for that case.

Units and conventions

• Z0 and ZL are impedances in the same units, conventionally ohms; their ratio is dimensionless.
• Z0 is assumed real and positive, and ZL may be complex in rectangular or polar form.
• Forward and reflected powers must use the same power units, such as both watts or both milliwatts; only their ratio is used.
• For power inputs, Pf must be positive and 0<=Pr<=Pf for a passive one-port.
• Angles in the complex-number UI must explicitly declare degrees or radians; the specification does not currently state which is used.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "Z0": "50 ohm",
    "ZL": "100 + j0 ohm"
  },
  "expected_outputs": {
    "reflection_coefficient": "1/3 + j0",
    "reflection_magnitude": 0.3333333333333333,
    "VSWR": 2,
    "return_loss_dB": 9.542425094393248,
    "mismatch_loss_dB": 0.511525224473813
  },
  "reference_data": {
    "formulas": [
      "Gamma=(ZL-Z0)/(ZL+Z0)",
      "VSWR=(1+abs(Gamma))/(1-abs(Gamma))",
      "RL=-20log10(abs(Gamma))",
      "ML=-10log10(1-abs(Gamma)^2)"
    ]
  },
  "working": "Gamma=(100-50)/(100+50)=50/150=1/3. |Gamma|=1/3. VSWR=(1+1/3)/(1-1/3)=(4/3)/(2/3)=2. RL=-20log10(1/3)=20log10(3)=9.542425094393248 dB. ML=-10log10(1-1/9)=-10log10(8/9)=10log10(9/8)=0.511525224473813 dB."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specified formulas have singular or out-of-domain cases that require explicit validation: ZL=-Z0 causes division by zero, |Gamma|=1 makes VSWR and mismatch loss infinite, and |Gamma|>1 produces a negative raw VSWR and a non-real mismatch-loss logarithm. The complex-impedance convention can also reverse the sign of the imaginary part of Gamma.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche8/tranche8-results.json
• BOUNDARY_HAZARD_CATALOG.json