For best performance, you must install the AF5 as high up as possible, with a line of sight free from obstructions. This is especially true in FDD (Frequency Division Duplexing) mode, as there is a requirement to maximize channel/spectrum reuse. Any objects in front of or near the front of the AF5 can have a significant impact on overall performance. The AF5 should be installed 1 m (3.3 ft) below the highest point of the structure to reduce the risk of a lightning strike. When the AF5 must be installed above a metallic surface like a corrugated flat roof or water tower, then you should ensure that the AF5 is located more than 3 m (10 feet) above the metal/reflective surface.
What is generally true for cellular installations is true for the AF5. You should mount the AF5 where it can see no reflections in the near field, so we recommend the following types of mounting sites:
- Perimeter mounting on a water tower/structure (best)
- Mounting near the edge of the top of a structure
- Mounting on an elevated mast or tower
Radios that are mounted anywhere near the surface of a roof or the top of a water tower can be significantly affected by reflections. FDD is more susceptible to the elements of a deployment environment than TDD (Time Division Duplexing) is.
You can find more useful tips for your AF5/5U installation here.