There are many losses to consider with a wireless network. You need to do a search on link calculation or link budget and you can find online calculators like this
Electro-Comm Distributing, RF Calculators. You need to consider these main losses, Insertion loss for connectors, Cable loss and free space loss. You also add into the equation any unforseen losses caused by bad weather or trees etc, as a figure called the Fade Margin.
Good luck,
Dale.
Calculate Losses Of Wireless 
Linear Mode
