Calculate radio coverage range and required antenna height from the radio horizon (line-of-sight) of the transmitter and receiver antennas.
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Radio Coverage Formula
The following approximation estimates the combined radio horizons of two antennas over a smooth Earth under standard refraction (effective Earth radius 4/3). It does not calculate a usable-signal coverage boundary.
- Where CD is the approximate radio-horizon distance (km)
- hโ is transmitter height above the local surface (m)
- hแตฃ is receiver height above the local surface (m)
Multiply the sum of the square roots of the antenna heights in meters by 4.12 to estimate kilometers. For minimum transmitter height, use hโ = max(0, CD/4.12 โ โhแตฃ)ยฒ. If the receiver horizon already reaches the target, the model minimum is zero.
What is a Radio Coverage Calculator?
Definition:
This Radio Coverage Calculator estimates radio-horizon distance from two antenna heights, or the minimum transmitter height for a target distance and known receiver height. It does not infer distance from transmitter power or gain.
How to Calculate Radio Coverage?
Example Problem:
The following example estimates radio-horizon distance from antenna heights.
First, select Radio-horizon distance.
Next, enter a transmitter height of 100 m and a receiver height of 0 m.
Finally, calculate the coverage distance using the formula above:
CD โ 4.12(โhโ + โhแตฃ)
CD โ 4.12(โ100 + โ0)
CD โ 4.12 ร 10
CD โ 41.2 km
FAQ
What factors can affect radio coverage?
Radio coverage can be influenced by several factors including transmitter power, antenna gain, frequency, terrain, obstacles, and environmental conditions. Interference and regulatory limits may also impact effective coverage.
Can this calculator be used for accurate real-world predictions?
This calculator estimates a smooth-Earth radio horizon under standard refraction. Terrain, obstacles, Fresnel clearance, atmospheric conditions and a full radio link budget require separate analysis; the result does not guarantee reception.
How do I choose the unknown quantity?
Use the Solve for selector to choose Radio-horizon distance or Minimum transmitter height. Enter every displayed required value; irrelevant inputs are hidden.
