Ham Radio Range Calculator
Calculate amateur radio communication range based on antenna heights, frequency bands, and environmental factors. Essential tool for licensed operators and radio enthusiasts.
Radio Configuration
meters
meters
Communication Range
Configure your radio setup and click "Calculate Range" to see results
Understanding Ham Radio Communication Range
Amateur radio communication range depends primarily on line-of-sight propagation and antenna height above ground. The basic principle is that radio waves travel in straight lines and can be obstructed by terrain, buildings, and the Earth's curvature.
Higher antennas extend the communication range by providing better line-of-sight paths. VHF and UHF frequencies used in amateur radio typically follow line-of-sight rules, while HF bands can achieve longer ranges through skywave propagation.
This calculator uses the standard radio horizon formula combined with frequency band adjustments and terrain factors to provide realistic range estimates for different amateur radio scenarios.
The Radio Range Calculation Formula
Line-of-Sight Distance Formula
Range = 3.57 × (√H₁ + √H₂)
Where range is in kilometers, and heights are in meters
This formula calculates the theoretical line-of-sight distance between two antennas accounting for Earth's curvature. The constant 3.57 comes from the Earth's radius and the radio wave propagation characteristics.
- H₁: Height of transmitting antenna (meters)
- H₂: Height of receiving antenna (meters)
- Range: Maximum line-of-sight distance (kilometers)
For example, with antennas at 10m and 5m height, the range would be approximately 3.57 × (√10 + √5) ≈ 3.57 × (3.16 + 2.24) ≈ 18.9 km. Band adjustments and terrain factors modify this base calculation for more accurate real-world estimates.
Typical Ham Radio Range Examples
Range Calculations for Common Scenarios
| H1 (m) | H2 (m) | Band | Terrain | Range (km) |
|---|---|---|---|---|
| 2 | 2 | 70cm | Open | 10.1 |
| 5 | 1.5 | 2m | Urban | 12.8 |
| 10 | 2 | 2m | Open | 17.0 |
| 20 | 3 | 6m | Hills | 21.6 |
| 15 | 15 | 2m | Sea | 41.4 |
| 50 | 10 | 70cm | Open | 32.4 |
Understanding the Table
These examples show how antenna height, frequency band, and terrain affect communication range. Higher antennas and favorable terrain (like sea paths) significantly increase range. Band adjustments account for frequency-specific propagation characteristics.