Fresnel Zone Calculator
Calculate Fresnel zone radius for wireless communication and antenna design
Calculate Fresnel Zone Parameters
Operating frequency of the wireless communication system
1st zone is most critical for signal transmission
Total line-of-sight distance between transmitter and receiver
Obstruction Analysis (Optional)
Fresnel Zone Results
Formula used: r = √(n × λ × D/4)
Zone #1: Most critical for signal quality
Applications: Microwave links, WiFi, cellular, satellite communications
Signal Quality Analysis
Example Calculation
WiFi Link (2.4 GHz)
Frequency: 2.437 GHz
Distance: 2 km
Zone: 1st Fresnel zone
Calculation
λ = c/f = 3×10⁸/2.437×10⁹ = 0.123m
r₁max = √(λ×D/4) = √(0.123×2000/4)
r₁max = 7.85 m
60% clearance: 4.71m
80% clearance: 6.28m
Common Wireless Bands
Design Guidelines
Keep 80% of 1st Fresnel zone clear (recommended)
60% clearance minimum for acceptable performance
Consider Earth curvature for distances > 5km
Higher frequencies = smaller Fresnel zones
Understanding Fresnel Zones
What are Fresnel Zones?
Fresnel zones are 3D elliptical regions between transmitter and receiver antennas where electromagnetic waves can travel. These zones determine whether obstructions will cause signal interference through reflection and phase shifting effects.
Why Keep Zones Clear?
- •Prevent destructive interference from reflected signals
- •Maintain signal strength and quality
- •Avoid phase cancellation effects
- •Ensure reliable wireless communication
Key Formulas
rmax = √(n × λ × D / 4)
r = √(n × λ × d₁ × d₂ / (d₁ + d₂))
λ = c / f
- r: Fresnel zone radius (m)
- n: Zone number (1, 2, 3, ...)
- λ: Wavelength (m)
- D: Total distance between antennas
- d₁, d₂: Distances from antennas to point
- c: Speed of light (3×10⁸ m/s)
- f: Frequency (Hz)
1st Zone Critical: Most important for signal quality
Applications and Design Considerations
Wireless Applications
- • Point-to-point microwave links
- • WiFi and wireless LAN installations
- • Cellular tower planning
- • Satellite ground station design
- • Amateur radio communications
- • Broadcasting transmitter sites
Design Factors
- • Antenna height planning
- • Obstacle clearance calculations
- • Site survey requirements
- • Earth curvature effects (>5km)
- • Atmospheric refraction
- • Vegetation growth planning
Practical Tips
Clearance Requirements:
- 80% clearance: Optimal performance
- 60% clearance: Acceptable performance
- <60% clearance: Signal degradation likely
Frequency Effects:
- Higher frequency = smaller zones
- Lower frequency = larger zones
- 2.4 GHz vs 5.8 GHz zone size difference