Radar Horizon Calculator
Calculate radar horizon distances and maximum line-of-sight coverage based on antenna height, target height, Earth radius, and atmospheric refraction factor. Radar Horizon Calculator helps engineers, aviation professionals, maritime operators, and communications planners estimate detection and visibility ranges.
Highlights
- Estimate radar detection range over the Earth's curved surface.
- Calculate radar and target horizon distances from elevation inputs.
- Account for atmospheric refraction with a customizable factor.
- Determine effective Earth radius for accurate propagation estimates.
- Useful for aviation, maritime, engineering, and communications planning.
Table of Contents
How Radar Horizon Calculator Works?
The Radar Horizon Calculator estimates how far a radar signal can travel before Earth’s curvature blocks direct line of sight. It uses the radar antenna height, target height, planetary radius, and an atmospheric refraction factor. Atmospheric refraction is represented by an effective Earth radius, which adjusts the curvature used in the calculation.
Here, is the effective Earth radius, is the atmospheric refraction factor, and is the entered Earth radius. A factor greater than 1 models propagation in which atmospheric refraction makes Earth appear less curved to the radar signal.
The radar horizon distance is calculated from the antenna height . The target’s contribution is calculated using the same geometric relationship:
The maximum radar horizon range is the sum of the radar-side and target-side horizon distances:
| Quantity | Meaning | Used in |
|---|---|---|
| Radar antenna height | Elevation of the radar above the surrounding surface | Radar horizon distance |
| Target height | Elevation of the detected object above the surrounding surface | Target horizon distance |
| Earth radius | Planetary curvature radius used by the model | Effective Earth radius |
| Refraction factor | Multiplier that adjusts the apparent curvature for atmospheric propagation | All horizon distances |
The calculator supports radar height and target height in m, km, ft, yd, mi, or nmi. Earth radius supports m, km, ft, mi, or nmi, while the refraction factor is entered as a dimensionless factor.
Practical Use Cases
Radar engineers can estimate the geometric detection limit of a radar installation by entering the antenna elevation, expected target height, Earth radius, and atmospheric refraction factor. This helps compare possible tower locations and assess whether a low-altitude target may be hidden by curvature.
Aviation professionals can use the calculator to approximate line-of-sight coverage for air-traffic surveillance, coastal monitoring, and airborne radar systems. Different aircraft or terrain-clearance heights can be tested to see how the target horizon changes.
Maritime operators can estimate how far a shipborne or shore-based radar may detect vessels, buoys, and other elevated targets over open water. Increasing antenna height or accounting for standard atmospheric refraction provides a quick planning estimate.
Communications planners can use the result as an initial line-of-sight check for radio, microwave, and other propagation links where surface curvature affects coverage. The maximum radar horizon range gives a first estimate of whether two elevated sites can be mutually visible under the selected model.
Accuracy and Limitations
The calculator uses a spherical-Earth tangent approximation with an effective radius equal to the entered Earth radius multiplied by the atmospheric refraction factor; it is most useful for unobstructed, near-surface line-of-sight estimates. It does not model terrain, hills, buildings, antenna beam width, radar power, receiver sensitivity, frequency-dependent propagation, ducting, weather variability, or the radar cross-section of the target. The maximum range is therefore a geometric horizon limit rather than a guaranteed detection range, and unusual atmospheric conditions may make the selected refraction factor inaccurate.
Quick Examples
Example #1: Coastal Surveillance
Estimate the radar detection range for a coastal radar monitoring low-altitude maritime targets.
Example #2: Mountain Radar Coverage
Calculate long-range line-of-sight coverage from a radar station positioned at high elevation.
Example #3: Air Traffic Detection
Estimate radar horizon range for an elevated radar system detecting aircraft at cruising altitude.
