⚠ Important — Please Read Before Using This Tool

LinkZoneTools LLC · Path Profile & Line of Sight Analysis · Terms of Use & Disclaimer

📋 Reference & Educational Use Only

This tool is provided for reference, planning, and educational purposes only. It is not intended to constitute, and shall not be construed as, professional RF engineering advice or a guarantee of wireless link performance. Results are estimates based on theoretical models and published data.

⚠ Tool-Specific Notice — Path Profile & Line of Sight Analysis

Terrain elevation data is sourced from third-party APIs (SRTM 90m / OpenTopoData / ASTER GDEM) representing ground surface only — buildings, trees, and above-ground structures are NOT included. Line-of-sight and Fresnel clearance determinations are based on this model data and may not reflect actual field conditions. Azimuth bearings and path distance depend on the accuracy of entered GPS coordinates. All results must be verified against a physical site survey before deployment.

🌐 Third-Party Data & APIs

This tool uses third-party data sources including OpenStreetMap geocoding and map tiles, Open-Meteo elevation API, OpenTopoData, and ASTER GDEM terrain data. LinkZoneTools LLC does not control these sources and makes no warranty as to their accuracy, availability, or currency.

⚖ Limitation of Liability — No Warranty

LINKZONETOOLS LLC PROVIDES THIS TOOL "AS IS" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. LINKZONETOOLS LLC SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR EXEMPLARY DAMAGES ARISING FROM USE OF OR RELIANCE ON THIS TOOL, INCLUDING FAILED WIRELESS LINK DEPLOYMENTS, EQUIPMENT LOSSES, LOST REVENUE, OR BUSINESS INTERRUPTION. THE USER ASSUMES ALL RESPONSIBILITY FOR FINAL DESIGN DECISIONS AND THEIR OUTCOMES.

👤 User Responsibility

By using this tool, you acknowledge that: (1) you will independently verify all outputs against current authoritative sources; (2) you will use manufacturer link planning software as the final design authority; (3) you will conduct a physical site survey before specifying equipment or antenna heights; and (4) LinkZoneTools LLC bears no responsibility for any errors, omissions, or outcomes resulting from use of this tool.

© LinkZoneTools LLC · Reference tool only · Not a substitute for professional RF engineering or a physical site survey.

Path Profile & Line of Sight Analysis

This tool answers one question: will this path physically work? It checks terrain clearance, line of sight, and Fresnel zone in a single pass — because line of sight alone is not enough to make a link perform.

1
Locate both sites
Enter an address and click Find, paste coordinates in any format (decimal or degrees-minutes-seconds), or click the map. Drag a marker to fine-tune. Path distance and both aiming azimuths update as you move.
2
Set antenna heights
Heights are above ground level. These drive everything downstream — clearance, Fresnel intrusion, and the minimum-height recommendation.
3
Fetch the terrain profile
Elevation is sampled along the path from public datasets. Remember these are bare earth: no trees, no buildings. Anything above ground you must add yourself in the next step.
4
Add obstructions
Enter tree lines, buildings and towers with a realistic extent along the path. Watch the height reference — AGL measures from the ground beneath, AMSL from sea level. Confusing them shifts the object by the entire terrain elevation.
5
Read the verdict
Green means clear. Amber means line of sight exists but the Fresnel zone is intruded — the link will underperform even though nothing blocks the direct ray. Red means terrain cuts the path outright.
6
Fix a failing path
The minimum-height figures tell you exactly how tall each end must be to clear both terrain and the Fresnel target. Raise one end or the other.
7
Note the rain zone
The ITU rain zone is derived from the path midpoint. Carry it into the Link Budget tool, where it drives the availability prediction.

Path viability is a geometric problem with an atmospheric correction. This tool evaluates terrain clearance against the effective-earth model and tests first Fresnel zone intrusion along the whole path, not just at midpoint.

Effective earth radius

Terrain is evaluated against a curved reference, not a flat one. The bulge at any point on the path is:

h(d₁) = d₁·d₂ / (2·k·Re)

with Re = 6,371,000 m and k = 4/3 for a standard atmosphere. On a 50 km path this puts roughly 37 m of apparent rise at midpoint. Sub-refractive conditions (k < 1) raise the effective obstruction and are the usual cause of paths that survey clear but fail intermittently at dawn.

Fresnel clearance criterion

r₁ = √(λ·d₁·d₂ / (d₁+d₂))

The radius is maximum at midpoint, where it reduces to √(λd/4). The tool reports clearance as a percentage of r₁ at the worst point on the path.

  • ≥ 60% of F1 clear — diffraction loss approximately 0 dB; treat as free-space
  • Grazing (0% clear, ray just touching) — about 6 dB loss
  • Full obstruction — knife-edge diffraction per ITU-R P.526, loss grows rapidly with obstruction depth

60% is the design minimum for unlicensed work. Licensed microwave is normally specified at 100% F1 clearance at k = 4/3 and 60% at k = 2/3, so the path survives sub-refraction.

Elevation data limitations

The profile is sampled from public DEM sources, which are bare-earth models. Canopy, structures and any recent construction are absent. Vertical accuracy for SRTM-class data is roughly ±16 m LE90, and horizontal posting is coarse enough that narrow ridges can be under-represented.

Practical consequence: a path showing 1–2 m of clearance is not clear. Treat anything inside the DEM error band as requiring a physical survey before you commit hardware.

Obstruction height reference

Obstructions accept AGL or AMSL. AGL is added to the interpolated terrain elevation at that chainage; AMSL is used absolutely. Mixing them displaces the object by the full terrain elevation at that point — the single most common source of a wrong verdict in this tool.

Minimum antenna heights

The recommended heights solve for the lowest pair that satisfies both terrain clearance and the Fresnel target simultaneously across every sample. Because the constraint is usually dominated by one controlling obstacle, raising the end nearer that obstacle is typically more efficient than raising both.

Rain zone handoff

The ITU rain zone is derived from the path midpoint per ITU-R P.837 and carried into the Link Budget tool, where R0.01 drives specific attenuation γ = k·Rα using the ITU-R P.838-3 coefficients. Below about 6 GHz the rain term is negligible; above 10 GHz it usually dominates the outage budget.

References: ITU-R P.526 (diffraction) · ITU-R P.530 (terrestrial LOS design) · ITU-R P.453 (refractive index) · ITU-R P.837 / P.838-3 (rain)
Every field has a ? tooltip for quick guidance and a 📚 Learn button for the concept behind it.
⚠ Reference tool only. Terrain data is ground surface only — buildings and vegetation not included. Verify with a site survey.
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Path Profile & Line of Sight Analysis

Terrain cross-section, line-of-sight verification, Fresnel clearance and obstruction modelling for point-to-point links.

Complete · Path Profile & LOS Analysis

Project ?

Unsaved
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Site Locations ?

A Site A
Latitude
Longitude
B Site B
Latitude
Longitude
📍 Tip: you can also click directly on the map to place a site. Click once for Site A, again for Site B.

Antennas & Terrain ?

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—
—
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Obstructions ?

No obstructions added. Terrain data excludes trees and buildings — add anything along the path that could block the link.

Path Summary ?

?
Path Distance ?
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Azimuth A → B ?
—°
Azimuth B → A ?
—°
✅ All stages complete. Location, terrain, line of sight, Fresnel clearance, obstruction modelling and ITU rain zone are live.

Site Map ?

Click the map to place a site · drag markers to adjust —

Terrain Profile ?

No data yet
⛰
No terrain profile yet
Set both site locations, then click Fetch Terrain Profile to sample ground elevation along the path.