Source: https://guthlabs.ai/docs/instruments/transmission-line-swr-calculator/implementation/

instrument implementation / implementation-contract

# Transmission Line / SWR Calculator implementation

A source-bound implementation contract for Transmission Line / SWR Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t8-014

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/transmission-line-swr-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/transmission-line-swr-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/transmission-line-swr-calculator/qualification/>)

## 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`