At 2.4GHz or 5GHz For a long range external link, the 2 antennas of 2 Wi-Fi devices must be absolutely at sight from each other. At this frequency (e.g. 2.4 GHz for 802.11b), the obstacles cause very strong signal attenuation.
In a closed and metallic environment (e.g. factory hall), it is strongly recommanded to use 2 antennas spaced out 1.5 times the wave length (Diversity feature). This technique lowers the fading effects (Disappearance of the wave due to rebounds and multiple paths on the obstacles).
The antenna is the essential element of the radio 's chain and one must grant a particular importance as well as for its cable which must be low loss type and with reasonnable length.
One must make sure, by establishing a radio link statement, the whole installation architecture is reliable for a quality communication. To do so, one must add gains and losses (in dB) of the different elements of the radio communication's chain: Transmitter output power + Transmitter antenna's cable loss + Transmitter antenna gain + Air loss + Receiver antenna gain + Receiver antenna's cable loss. The total value must be higher than the sensibility of the Receiver (Add a security margin of 6dB).
PRODUCTS > Antennas
