Source: https://guthlabs.ai/docs/instruments/emc-emi-near-field-distance-wavelength-calculator/mechanism/

instrument mechanism / verified-clean

# EMC/EMI Near-Field Distance & Wavelength Calculator mechanism

The inspectable method record for EMC/EMI Near-Field Distance & Wavelength Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The wavelength formula is standard under SI units. The distance formulas are conditional engineering rules of thumb, and the honest-label warning is appropriate, but the product needs explicit SI input units, D definition, domain constraints, and unambiguous output labels before release.

- The formula λ/2π is a rule-of-thumb scale associated with reactive near-field behavior for some source types; labeling it a general far-field boundary is ambiguous and is not universally valid.

- The Fraunhofer distance 2D²/λ is a standard rule of thumb for the far-field boundary when D is the maximum physical aperture or structure dimension, but its applicability and numerical factor depend on geometry and allowable phase error.

- The specification does not define whether the two distances are separate outputs, whether one should be selected, or whether the larger distance should be treated as the conservative boundary.

- The specification does not state whether D is the maximum overall dimension, aperture diameter, cable length, or another characteristic dimension.

## Units and conventions

- Frequency must be supplied in hertz (Hz).

- Antenna or structure size D must be supplied in metres (m).

- Wavelength is computed in metres using c = 299792458 m/s.

- The λ/2π distance and 2D²/λ distance are approximate rule-of-thumb values, not geometry-independent EMC limits.

- D must be a nonnegative physical length; the Fraunhofer result is unavailable when D is omitted.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "frequency_hz": 100000000,
    "D_m": 0.3
  },
  "expected_outputs": {
    "wavelength_m": 2.99792458,
    "reactive_scale_m": 0.477134516,
    "fraunhofer_boundary_m": 0.060041537
  },
  "working": "λ = c/f = 299792458 / 100000000 = 2.99792458 m. Reactive scale = λ/(2π) = 2.99792458 / 6.283185307 = 0.477134516 m. Fraunhofer boundary = 2D²/λ = 2(0.3²)/2.99792458 = 2(0.09)/2.99792458 = 0.18/2.99792458 = 0.060041537 m."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The zero-frequency vector exposes an undefined division-by-zero case that must be rejected. The unit probe also exposes a severe convention hazard: ignoring the D unit changes the Fraunhofer result by four orders of magnitude.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/emc-emi-near-field-distance-wavelength-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/emc-emi-near-field-distance-wavelength-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/emc-emi-near-field-distance-wavelength-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-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`