Antenna:
Crossbow recommends an external, ¼ wave whip antennae. These antennae are
inexpensive and offer improved coverage. The MICA2 has an MMCX connector for easy
connection to many types of external antennas. All sensors should be placed such that the
antennas are oriented vertically. Horizontal placement of the antennae will result in a substantial
loss of distance.
Radio Range:
Lower radio frequencies for example, 433 MHz, will have longer ranges in an
outdoor deployment. Depending on the foliage and environmental conditions, expect ranges of
200-500 feet at 433 MHz and 100-300 feet with 916 MHz. Remember, the XMesh stack will
automatically configure the network and allow for radio range extension via message hopping
across multiple deployed sensors.
Placement:
Units are usually placed at least 1-3 feet above the ground. Placing units at ground
level will decrease communication range. Grass and other foliage will also decrease distance.
Crossbow recommends the following average mesh grid density:
916 MHz: 1 mote/2500 sq feet (50’ by 50’).
433 MHz 1 mote/10000 sq feet (100’ by 100’).
Foliage and other RF obstacles will decrease distance. However, if the units are deployed such
that motes can find other motes (parents) then the network will automatically reroute radio traffic.
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