Path Parameters
Calculated Results
Line of Sight Distance ($d_{los}$): --
Radio Horizon ($d_r$): --
1st Fresnel Zone Radius: --
Fresnel Clearance at Midpoint: --
Drag the slider to adjust the obstacle's height.
Obstacle Height: 0mHow It Works: The Formulas Behind LOS
Visual Line of Sight
The maximum distance to the horizon from an antenna at height ($h$):
$$d_{los} = 3.57\sqrt{h}$$
(where $d_{los}$ is in km and $h$ is in meters)
Radio Horizon
Radio waves bend with Earth's curvature, extending the range beyond the visual horizon:
$$d_r=4.12\sqrt{h}$$
(where $d_r$ is in km and $h$ is in meters)
The Fresnel Zone
A clear ellipsoidal area around the direct path is required. Obstructions here cause attenuation. The radius ($r$) at midpoint is:
$$r = 17.32\sqrt{\frac{d}{4f}}$$
(where $r$ is in meters, $d$ is in km, and $f$ is in GHz)
Ideally, ensure at least **60% clearance** of the first Fresnel Zone.
Related Tools
Engineering checks for Line of Sight Calculator
Before using Line of Sight Calculator in a PCB, firmware, repair, or validation workflow, confirm the details that usually decide whether the design works reliably instead of only reading the headline specification.
Design and troubleshooting checklist
| Area | What to check | Why it matters |
|---|---|---|
| Formula inputs | Check the units, tolerance, and boundary values used by the line of sight calculator between two points calculation | Wrong units or ideal assumptions can make a correct formula misleading |
| Circuit context | Compare the result with voltage, current, power, thermal, and safety limits on the PCB | Calculator output still needs board-level validation |
| Verification | Confirm the result with datasheet limits, simulation, or bench measurement before release | Measured behavior catches parasitics and loading effects |
