Antenna Length Calculator (dipole/monopole/whip)

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Electrical & Electronics Engineering — Circuits, Power Systems, Electronics Lab

Tranche

tranche-5

Evidence ID

t5-050

Ledger rows

1

No ledger note is attached.

Review findings

The dipole and quarter-wave monopole approximations are standard when frequency is in MHz, output is in feet, and the embedded empirical 0.95 factor is intended. The specification needs revision before PASS: define whether the velocity-factor input overrides the embedded factor, require explicit frequency units, and define separate Yagi element assumptions or remove Yagi from the claimed scope. The honest-label warning is appropriate but should explicitly mention that Yagi element lengths and spacing require additional design parameters.

Formula and scope findings

• The dipole formula L=468/f(MHz) ft is a valid empirical half-wave-dipole approximation corresponding approximately to 0.95 times the free-space half-wavelength, but it is not a general formula for an arbitrary velocity factor input.
• The monopole formula L=234/f(MHz) ft is the corresponding quarter-wave approximation, also embedding approximately a 0.95 factor; a supplied velocity-factor input is otherwise unused and its intended effect is ambiguous.
• No formula is specified for a Yagi element. A Yagi reflector, driven element, and directors do not all have the same length, so the claimed Yagi computation is underdefined.
• The wavelength formula λ=c/f requires explicit frequency units and a stated value and unit for c; the empirical length formulas require frequency in MHz and output feet.

Unit assumptions

• For λ=c/f, c=299792458 m/s and frequency is converted to Hz; wavelength output is meters.
• For 468/f and 234/f, frequency is in MHz and output length is feet.
• The constants 468 and 234 already include an approximate 0.95 end-effect or velocity-factor correction relative to an ideal free-space half-wave or quarter-wave length.
• The reported dipole total length is the full tip-to-tip length, and each dipole half is total length divided by two.
• The Yagi test vector treats the requested element as an assumed half-wave element using the dipole constant; this is only a stated approximation, not a uniquely correct Yagi formula.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

Zero frequency produces undefined wavelength and antenna length, requiring rejection. Negative frequency also exposes an unresolved sign convention: literal arithmetic returns negative physical lengths, while a magnitude convention returns positive lengths.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "frequency": 14.2,
    "frequency_unit": "MHz",
    "antenna_type": "dipole",
    "velocity_factor": 0.95
  },
  "expected_outputs": {
    "wavelength_m": 21.11214493,
    "total_length_ft": 32.95774648,
    "per_element_length_ft": 16.47887324
  },
  "working": "Convert frequency: 14.2 MHz = 14,200,000 Hz. Wavelength = 299,792,458 / 14,200,000 = 21.11214493 m. Dipole total = 468 / 14.2 = 32.95774648 ft. Each half = 32.95774648 / 2 = 16.47887324 ft."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json