Calculator Inputs
Example Data Table
| Scenario | Distance | Frequency | Obstacle | Clearance Target | Typical Outcome |
|---|---|---|---|---|---|
| Rooftop to rooftop | 2.0 km | 5.8 GHz | 12 m parapet at 1.0 km | 60% Fresnel + 1 m margin | Small raise at nearer end often works. |
| Mid‑rise to tower | 6.5 km | 2.4 GHz | 25 m building at 2.3 km | 60% Fresnel + 2 m margin | Curvature effect becomes noticeable. |
| Long temporary link | 18 km | 1.8 GHz | 18 m ridge at 9.0 km | 60% Fresnel + 3 m margin | Higher masts needed for reliability. |
Formula Used
How to Use This Calculator
- Choose your unit system for field entry.
- Enter site elevations and mast heights for both ends.
- Provide total distance and obstacle location from Site A.
- Enter obstacle base elevation and its height above ground.
- Set frequency, k‑factor, Fresnel target, and margin.
- Press Calculate to view results above the form.
- Use CSV or PDF buttons to export the computed report.
Planning Inputs That Control Elevation
Accurate planning starts with measured site elevations, mast heights, and realistic path distance. For urban links under 2 km, obstruction height dominates. Beyond 5 km, curvature and refraction matter. Use k‑factor near 1.33 as a baseline. Enter obstacle position from Site A so the line‑of‑sight height is evaluated at that point.
Curvature, Refraction, and Construction Reality
Curvature bulge increases with d1×d2, so mid‑path obstructions are most critical. Refraction varies, so test k‑factor sensitivity during review. If a scaffold or crane is expected, add it as obstacle height and include margin. A 1–3 m buffer helps for sway, tolerances, and survey uncertainty.
Fresnel Zone Targets for Reliable Links
Clearing only the visual line is rarely enough at microwave bands. Many teams target 60% of the first Fresnel zone for dependable throughput and fewer fades. Lower frequencies produce larger Fresnel radii, so a 2.4 GHz hop may need higher mounts than a 5.8 GHz hop at the same distance. Set the percentage to match uptime goals.
Interpreting the Results Section
The results show line‑of‑sight height at the obstacle, required height after bulge, margin, and Fresnel target, and the remaining clearance. A positive clearance means the design meets the chosen standard. When there is a deficit, the tool estimates added mast height needed at Site A only or Site B only. Raising the nearer end gives more benefit per meter. For multi‑obstacle routes, run separate checks for each peak and choose the highest required elevation before ordering towers and brackets on the site.
Exporting and Sharing for Site Coordination
CSV exports support quick review with quantity takeoffs and permit packages, while the PDF summary helps field crews and subcontractors. Save results with project name and revision date, then re‑run the calculator whenever rooftop equipment changes. Pair the report with photos and survey notes to confirm temporary obstructions are removed before commissioning and acceptance testing.