Field-Engineer's Calculator Suite
Every number a working RF safety engineer reaches for, in one place. Convert dB ↔ dBm ↔ dBi, compute EIRP, ERP, free-space path loss, far-field distance, VSWR, cable losses; calculate power density and compliance distance under FCC OET-65; cross-walk to ISED Canada Safety Code 6 (ICNIRP-aligned). Inputs update outputs live — no submit button.
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Convert between decibels and a power ratio. Use the amplitude toggle for voltages or field strengths.
Edit any field — the others recompute. dBm is referenced to 1 mW; dBW is referenced to 1 W (offset 30 dB).
A half-wave dipole has 2.15 dBi of gain over an isotropic radiator. dBd subtracts that reference.
FCC and ITU spec sheets typically use dBi. Older broadcast antenna catalogs often quote dBd.
The three numbers every line sweep produces. Edit any one — the others recompute.
Free-space wavelength at the speed of light. Useful for first-cut antenna sizing, near/far-field bounds, and Fresnel-zone math.
Below this distance you are in the radiating near-field — power-density math from FSPL or Friis breaks down. Plug in the antenna's largest physical dimension.
Tx power minus cable losses plus antenna gain. EIRP references isotropic; ERP references a half-wave dipole (subtract 2.15 dB).
Path loss for a clear line-of-sight link with no obstructions, ground reflection, or atmospheric absorption. Floor of every link budget.
End-to-end signal level at the receiver. Useful for quick microwave / backhaul / 5G NR LOS sanity checks.
Far-field power density on boresight. Compare against the MPE limit for your population (lookup below).
Solve for distance that satisfies S ≤ MPE. Worst-case (free-space) bound; real exclusion zones are typically smaller.
Maximum Permissible Exposure power-density limits per FCC OET-65, Table 1. Type any cellular frequency to see the limit for that band.
| FREQUENCY RANGE | GENERAL PUBLIC | OCCUPATIONAL |
|---|---|---|
| 3 – 30 MHz | 180/f² mW/cm² | 900/f² mW/cm² |
| 30 – 300 MHz | 0.2 mW/cm² | 1.0 mW/cm² |
| 300 – 1500 MHz | f / 1500 mW/cm² | f / 300 mW/cm² |
| 1.5 – 100 GHz | 1.0 mW/cm² | 5.0 mW/cm² |
Source: FCC OET Bulletin 65, Edition 97-01, Table 1 (limits for Maximum Permissible Exposure). Below 3 MHz the limits are E-/H-field driven and not shown here.
Power-density limits at any frequency under both regulators. ISED column reflects ICNIRP-aligned reference levels approximating Health Canada Safety Code 6 (2015) for the cellular / microwave bands.
| POPULATION | FCC OET-65 (USA) | ISED · SC6 (Canada / ICNIRP) | Δ (Stricter) |
|---|---|---|---|
| General Public / Uncontrolled | — | — | — |
| Occupational / Controlled | — | — | — |
| Time-Averaging (GP / Occ) | 30 / 6 min | 6 / 6 min | — |
For a cross-border program, the time-averaging difference alone can flip a borderline site. ICNIRP's GP curve is f/2000 mW/cm² over 400–2000 MHz; FCC's is f/1500 over 300–1500 MHz then capped at 1.0. Always reference the source regulatory text for compliance work.
Total cable + connector loss for a Tx feed. Pick a common cable type to autofill attenuation per 100 ft at the typical band centers; or enter your own.
Manufacturer datasheets are the authoritative source. Values shown are typical at 25 °C and tend to increase with temperature and age.