| Scenario | Model | Frequency | Tx / Rx gains | Sensitivity | Margin + extra loss | Estimated radius |
|---|---|---|---|---|---|---|
| Open yard radios | Free Space | 900 MHz | 2 dBi / 2 dBi | −100 dBm | 15 dB + 5 dB | ~1.8 km (planning) |
| Dense site, taller mast | COST-231 | 1800 MHz | 6 dBi / 0 dBi | −95 dBm | 20 dB + 10 dB | ~2–6 km (model-dependent) |
| Interior floors, concrete slabs | ITU Indoor | 2400 MHz | 2 dBi / 2 dBi | −90 dBm | 10 dB + 12 dB | ~40–120 m (building-dependent) |
Received power is estimated as:
To meet reliability, we require: Pr ≥ ReceiverSensitivity + FadeMargin. Rearranging gives the maximum allowable propagation loss:
The calculator inverts this equation to solve for distance when FSPL = PathLossmax.
Area-type corrections adjust the loss for suburban and open environments.
Floor loss Lf(n) increases with the number of floors between radios.
- Pick a propagation model that matches your site conditions.
- Enter frequency, transmit power, antenna gains, and feeder losses.
- Use receiver sensitivity from your equipment datasheet.
- Set fade margin for reliability under movement and weather.
- Add extra loss for walls, foliage, terrain, and metal clutter.
- Submit to see radius, diameter, and circular coverage area.
- Export the report as CSV or PDF for documentation.
RF radius planning for active construction zones
Temporary sites change daily, so radius estimates should be conservative. A 10–20 dB fade margin is typical when vehicles, cranes, and steel frames introduce fast multipath. If crews move between decks or behind concrete cores, include 5–15 dB additional loss to reflect obstructions and dust-filled corridors. For critical coverage, confirm with spectrum scans and edge testing during peak site activity.
Inputs that most affect coverage distance
Link budget drives the allowable path loss. Every 3 dB gain from antennas or reduced feeder loss can roughly improve reach by about 1.4× in free-space conditions. Sensitivity matters too: improving receiver sensitivity from −90 to −96 dBm adds 6 dB, often producing a meaningful radius increase for the same frequency and margins.
Model selection for outdoor, mixed, and indoor areas
Use Free Space for clear line-of-sight spans such as open yards, haul roads, or tower-to-tower links. Use COST-231 Hata for outdoor macro planning around dense structures, where antenna height and environment type (urban, suburban, open) change the slope of loss with distance. Use ITU Indoor for basements, plant rooms, and interior floors.
Turning radius into placement decisions
Convert the radius into a coverage circle to compare against the working footprint. If the diameter is smaller than the longest crew route, plan intermediate relay locations. Raise site antennas where safe and permitted; height increases are often more effective than extra transmit power in cluttered zones, and may reduce dead spots.
Example data for quick verification checks
Use these planning inputs to sanity-check your entries before field testing:
| Use case | Model | f (MHz) | TxP (dBm) | RxSens (dBm) | Margin + extra (dB) |
|---|---|---|---|---|---|
| Open yard comms | Free Space | 900 | 33 | −100 | 15 + 5 |
| Dense perimeter patrol | COST-231 | 1800 | 30 | −95 | 20 + 10 |
| Interior stairwells | ITU Indoor | 2400 | 20 | −90 | 10 + 12 |
1) What does “additional loss” represent on site?
It represents extra attenuation from walls, rebar, machinery, terrain clutter, and foliage. Add it when line-of-sight is blocked or reflections dominate. Start with 5–15 dB, then refine using walk tests.
2) Which propagation model should I pick first?
Pick Free Space for clear line-of-sight. Pick COST-231 for outdoor coverage around buildings and dense structures. Pick ITU Indoor for enclosed spaces, basements, and multi-floor interiors where slab losses dominate.
3) Why can my result look unrealistically large?
High transmit power, large antenna gains, low margins, and minimal losses can create huge allowable path loss. Increase fade margin and add realistic losses, and verify frequency and sensitivity units to keep outputs practical.
4) How do I choose a fade margin value?
For steady links with good line-of-sight, 10–15 dB is common. For mobile crews, heavy equipment movement, and variable weather, 15–25 dB is safer. Use higher margins when safety communications must be reliable.
5) Does raising the antenna always help more than power?
Often, yes. Height can reduce obstructions and improve propagation in clutter, especially outdoors. Power increases may be limited by regulations and can raise interference. Combine modest power with better placement for best results.
6) Can I use this for Wi‑Fi or private LTE on site?
Yes, as a planning estimate. Use the correct frequency, device sensitivity, antenna gains, and realistic losses. For Wi‑Fi indoors, ITU Indoor is usually a better first pass than outdoor macro models.
7) Should I trust the radius as a guaranteed boundary?
No. It is a planning radius based on assumptions. Real sites have shadowing, reflections, and interference. Treat the output as a starting point, then validate with measurements and adjust margins and losses accordingly.