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Chapter 4: Trees and Other Obstacles

This section discusses the effects of trees (and other obstacles) on your link. Some frequencies, such as 900 Mhz and 2.4 Ghz do ok with trees. Some, such as 5.8 Ghz and above, can be completely blocked by a single tree. It varies, but a good rule of thumb is: avoid foliage!

Many in the WISP industry will repeat an oft-stated fact: Trees are the enemy. This may be overdramatic, but trees can really ruin an otherwise nicely operating wireless network. As a rule-of-thumb, for most WISP operations you require line-of-sight or near-line-of-sight. Different frequency bands respond to obstructions differently:

When planning wireless links, you want to start by searching for line-of-sight. From the receiver, you should be able to visually see the transmitter (and vice versa). Trial-and-error may permit other links to work (especially the lower frequencies), but it is not a good idea to count on it. It is generally easier to increase the elevation of the receiver or transmitter (or saw down a tree!) than it is to rely on penetrating the foliage.

Fixed obstacles such as buildings and mountains cannot be reliably penetrated, and you should search for paths around them.

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