Drop in power in a directed microwave beam?

[Patrick Pihl]

Would it be a drop in power as the square of the distance in a directed microwave beam? Thanks!

 

[mfb]

For small distances: probably not.
For very large distances: yes.

The typical length scale is (antenna diameter)^2 / (wavelength), focusing something over a longer distance does not work.

 

[Patrick Pihl]

Thanks! What would be a short / large distance in this context?

 

[mfb]

Did you see my comment about the length scale? If you are at 5+ times this length scale the inverse squared distance is a good scaling law. If you are below that length, it does not have to be a good approximation. It might be, but that depends on the beam then. In between, things are in between those two cases.