Wednesday, November 25, 2009

Canopy Antenna





A typical Canopy setup consists of a cluster of up to 6 co-located standard access points, each with a 60 degree horizontal beamwidth antenna, to achieve 360 degree coverage. The most commonly used APs are now available in 120, 180, or even 360 degrees for site-based coverage, thus decreasing the need for so many APs on a tower. Also included would be one or more backhauls or otherwise out-of-band links (to carry data to/from other network occasions) and a Cluster Management Module (CMM) to provide power and synchronization to each Canopy AP or Backhaul Module(BM).

Customers of the system receive service through subscriber modules (SMs) aimed towards the AP. The SMs should be mounted on the tall point of a building to get a reliable connection else Fresnel zone obstruction will weaken the signal. Under ideal operating conditions connections at distances up to 3.5 miles can be achieved using equipment with integrated antennas. Network operators can opt to install reflector dishes or Stinger antennas, or to use Canopy models that accept external antennas at one or both ends of the link to increase coverage distance.

Most Canopy equipment receives its power using Power over Ethernet, however, none of its standards comply with IEEE 802.3af.

In general, the 900 MHz version is more effective for use in outlying areas because of its ability to penetrate through trees. However, it requires careful installation due to the easy propagation of interference on that band. Other frequencies currently available are the 2.4Ghz, 5.2Ghz, 5.4Ghz, and 5.7Ghz versions.

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