Microwave Planning Before and After.

Before getting to the nuts and bolts of designing a link, some fundamental terms and concepts need to be reviewed
Free Space Loss.
Fresnel Zone.
Receive signal level.
Receiver sensitivity
Antenna gain
Transmit Power.
Effective Isotropic Radiated Power
System Operating Margin.
Multipath Interference.
Signal-to-Noise Ratio.
Why Perform an SOM Calculation?
What Is the Minimum SOM Needed?

But even if your Fresnel zone is partially blocked, it is still possible to get a link, provided that your system was designed to have a strong signal at the other end of the link. In planning long-range microwave links where you are not sure that you have unobstructed line-of-site and clear Fresnel zone, an RF path analysis should be done. There are many software packages available that have terrain data and can create a path profile from a set of latitude/longitude coordinates. But these programs can only indicate for certain if a link will not work due to terrain obstruction. A clear path on paper is not a guarantee that your link will work, since it does not show trees or buildings. So even a “clear” link might have 80-foot trees in the way that could block the signal