How do I hook up four 90 degree sector panels on one tower?
Conventional thought says that there aren’t enough non-overlapping 2.4 GHz DSSS channels to put 4 channels on one tower. Usually, panel antennas with high F/B are selected, and channel 1 antennas are placed on opposite sides (e.g. North & South) and channel 11 antennas are also placed on opposite sides (e.g. East & West). If separate access-points are used for all 4 antennas, the isolation may need to be increased between antennas on the same channel by spacing them farther from the tower face or on opposite corners of a building. FHSS systems may use separate frequency sets on each panel without problems. However, there is new evidence that supports the use of DSSS channels 1,4,8 and 11 on the same tower. A white paper from Cirond Networks discusses this possibility. Also, check out this article from ExtremeTech. Isolation will need to be increased between antennas in this case by spacing them farther from the tower face, or by vertical separation of 10 feet or more.
