Wi-Fi HaLow Radio Technology 10
Effect of Environmental Elements: Fresnel Zone
When a radio signal travels between two points, it doesn't stay in a perfect line. The area it occupies
is called the Fresnel Zone. When the Fresnel zone is free from obstructions, the signal strength is
improved.
Generally, the higher the transmitter and the receiver antennas are placed above the ground, the
longer the range that can be achieved. In the case of the Trimble SX12 and EM130 module, it's not
always possible or practical to have the two antennas high in the air. It's generally expected that the
antenna height on the total station would be about 1.8 m, and antenna height for EM130 module
would be about 1.5 m.
In the below example, the hill impedes the fresnel zone. At such a short distance, the impact on
performance is not noticeable, but if the surveyor wanted to walk a long distance to the right and
further downhill, they would eventually notice degraded performance or reduced range. When
possible, try to plan instrument setups so that the total station is at a higher elevation, like the top
of a small hill to help achieve the furthest possible range and best performance.
