What does this tool do?
This tool shows you how well a tower with one or more sector antennas would cover the surrounding area. You place a tower on the map, set up your antennas (pointing direction, beam width, power, etc.), and the tool calculates which areas around the tower can receive a usable signal — shown as color-coded zones on the map.
Key concepts explained simply
- Sector antenna: Unlike a traditional omni antenna that radiates equally in all directions, a sector antenna focuses the signal into a "slice" of the compass — like a flashlight instead of a light bulb. You can add up to 6 sectors to simulate a full multi-sector tower site.
- Azimuth: The compass direction the center of the antenna beam is pointing. 0° = North, 90° = East, 180° = South, 270° = West.
- Beamwidth: How wide the antenna's beam is. A 90° sector covers a quarter of the compass. A 120° sector covers a third.
- Coverage radius: How far you want to check for coverage. Larger radius = more calculations = slower.
- Signal strength colors: Green = strong signal, yellow = marginal, red = weak. Grey areas have no coverage.
How to use it
- Click the map or type an address to place your tower location
- Set your tower height, frequency, and Rx sensitivity threshold
- Configure each sector (azimuth, beamwidth, antenna gain, Tx power)
- Click "Generate Multi-Sector Coverage Map" and wait for the terrain analysis
- Use "Save Project" to store your configuration for later
💡 Important: This tool shows theoretical line-of-sight coverage only — it does not account for buildings, trees, or other above-ground obstructions. Real-world coverage is typically less than what the tool shows, especially in urban and suburban areas.
Signal Model
Coverage is computed using Free Space Path Loss (ITU-R P.525): FSPL(dB) = 20·log₁₀(d_km) + 20·log₁₀(f_GHz) + 92.45, combined with a Gaussian antenna pattern model for the main lobe (-3 dB at ±HPBW/2), linear sidelobe taper from HPBW edge to 90°, and back lobe at -30 dBc. RSL = EIRP - FSPL + gain_at_bearing. Coverage is shown where RSL ≥ Rx sensitivity threshold.
Antenna Pattern Model
- Main lobe: G(θ) = G_peak - k·θ² where k = 3.0103/half² (ensures -3 dB exactly at ±HPBW/2)
- Sidelobe region (HPBW/2 to 90°): Linear taper, -20 dB at HPBW edge to -35 dB at 90°
- Back lobe (90°–180°): Fixed -30 dBc below peak
Terrain LOS
Terrain elevations fetched from Open-Meteo (SRTM 90m, free, CORS-enabled) in batches of 100 points per API request. LOS check uses intermediate ring elevations as proxies — not a full per-point terrain profile (which would require ~100× more API calls). Earth bulge applied using k=4/3 standard atmosphere: h_bulge = d1·d2 / (2·k·Re).
Coverage Grid
Adaptive polar grid: rings × rays scaled to coverage radius. At 5 km radius: 16 rings × 36 rays = 576 sample points per sector. Coverage area estimated as: N_covered × (π·r² / N_total) km². Polygon cells rendered as Leaflet SVG polygons.
Limitations
- SRTM 90m terrain data — ground surface only, no buildings or vegetation
- LOS approximated from sampled ring elevations, not full per-point terrain profile
- No rain fade, multipath, or interference modelling
- Overlap between sectors not merged — shown at reduced opacity
- Coverage area estimate is geometric approximation ±10–15%
📋 Standard reference: FSPL per ITU-R P.525. Earth bulge per ITU-R P.530 (k=4/3 standard atmosphere). Antenna pattern is a simplified model — not derived from a specific ITU recommendation.
