The Fresnel Zone conversion calculator determines the radius of the first Fresnel zone between two antennas for a given distance and frequency. It helps evaluate how much clearance is needed to minimize signal obstruction and loss in line-of-sight communication links. The calculator provides results in both meters and feet, making it suitable for wireless, microwave, and optical path design.
Formulas
Radius (m) = 17.31 * sqrt( D_km / (4 * f_GHz) )
Radius (ft) = 72.05 * sqrt( D_miles / (4 * f_GHz) )
Formula Explanation
- D_km is the total distance between the transmitter and receiver in kilometers.
- D_miles is the same distance expressed in miles.
- f_GHz is the operating frequency in gigahertz.
- The constants 17.31 and 72.05 are derived from the wavelength of the signal and conversion between units.
- The formula assumes the first Fresnel zone, which is the most significant for maintaining clear signal paths.
Uses of this calculator
- Planning microwave or radio communication links.
- Ensuring proper antenna placement and line-of-sight clearance.
- Analyzing terrain obstructions for long-distance communication paths.
- Educational applications in wireless propagation studies.
Fresnel zone for 10 km link at 5 GHz
Input: Distance = 10 km, Frequency = 5 GHz
Output:
- Radius = 17.31 * sqrt(10 / (4 * 5)) = 17.31 * sqrt(0.5) = 17.31 * 0.7071 = 12.25 meters
- Radius = 72.05 * sqrt(6.21 / (4 * 5)) = 72.05 * sqrt(0.3105) = 72.05 * 0.5574 = 40.17 feet