PLANET WNAP-7200 - Manual (Page 74)

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For example, the wireless link between the building A and the building B is located three
miles (4.8 km) away. There is a tree-covered hill in the mid-way. From the table above, it can
be seen that for a three-mile link and the object clearance required at the mid-point is 5.4 m
(17.6 ft). The tree-covered hill height is at an elevation of 17 m (56 ft), so the antennas
linkage on both sides needs to be at least 22.4 m (73 ft) high. The building A is six stories
high or 20 m (66 ft), so the mast or pole with 2.4 m (7.9 ft) must be constructed on its roof to
meet the required antenna height. The building B is only three stories high or 9 m (30 ft) but
it is located at an elevation that is 12 m (39 ft) higher than the building A. A mast or pole is
required to mount an antenna at the required height 1.4 m (4.6ft) on the roof of building B.