Estimate a free-space radius for a private 5G link from a transparent RF budget. Frequency, transmitter power, antenna gains, receiver sensitivity, installation losses, and fade margin determine the maximum allowed path loss and ideal distance. Use the result as an early comparison between configurations; factories, warehouses, campuses, and outdoor sites need environment-specific propagation modeling and field validation.
The main result is the free-space distance at which modeled received power reaches the sensitivity threshold after losses and fade margin. It is an upper-bound planning figure, not a coverage promise.
The free-space path-loss equation assumes an unobstructed far-field path. Use an environment-specific propagation model and comply with applicable power and spectrum rules.
At 3.7 GHz, 37 dBm transmit power, 6 dBi transmit gain, 0 dBi receive gain, -97 dBm sensitivity, 4 dB losses, and 18 dB margin, maximum path loss is 118.0 dB. The free-space radius is 5.12 km.
No. It is a free-space link-budget estimate. Buildings, foliage, terrain, interference, antenna height, and local regulations can reduce usable coverage.
Free-space path loss rises with frequency for the same distance, so the same link budget reaches a shorter distance.
Use the device or modem sensitivity for the required channel bandwidth, modulation, coding, and performance target. A best-case data-sheet value may overstate coverage.
Reserve margin for shadowing, fading, weather, interference, and modeling uncertainty. Larger margin produces a more conservative radius.
Not by itself. Cell count also depends on site geometry, overlap, indoor penetration, traffic capacity, handover design, exclusions, and terrain.
| Variable | Meaning | Unit |
|---|---|---|
| Frequency | Carrier used in free-space path loss | GHz |
| Tx power | Conducted transmitter output | dBm |
| Antenna gains | Directional gain at each end | dBi |
| Sensitivity | Minimum modeled receive level | dBm |
| Losses | Feedline and miscellaneous attenuation | dB |
| Fade margin | Reserve for variation and uncertainty | dB |