Networking
Networking solutions that keep your business connected and productive -- lowering communication costs, enhancing efficiency and improving customer service.
Wireless Link Clearance Calculator
Check the clearance a point-to-point wireless link needs over trees and roofs, and its path loss.
60% of the first Fresnel zone is the usual minimum.
Results
First Fresnel zone radius at the midpoint: 5.09 m
Clearance for 60% of it: 3.05 m
Earth curvature at the midpoint: 0.06 m
Height above obstacles at the midpoint: 3.11 m
Free-space path loss: 113.7 dB
Signal at the receiver (before cable loss): -47.7 dBm
Earth curvature uses the standard 4/3 earth radius for radio. Keep trees, roofs and terrain below the clearance line along the whole path, not just at the midpoint. Check the received signal against the radio's sensitivity and leave a fade margin.
How it works
The first Fresnel zone radius at the middle of the link is 17.32 x the square root of the distance in km divided by 4 x the frequency in GHz, in metres, and at least 60% of it should be clear. The earth bulges by the distance squared divided by 8 x 4/3 x 6,371 km at the midpoint. Free-space path loss is 20 log(distance in km) + 20 log(frequency in GHz) + 92.45 dB.
Need help designing a system? Talk to our team, or see all 23 free calculators.
Now you have the number
Shop the parts.
Prices are shown to everyone. Sign in for member pricing, or ask us and we will quote the lot.
Can't see what you need? Tell us the spec and we will source it.