alt Hacker NewsVHF is effectively line-of-sight, and no antenna size can change that (although it does improve efficiency for both sending and receiving), so for two handheld radios, you are limited to about 10 km.
The only thing that really helps extend the range is elevating the antenna, and repeaters allow you to do that even between two mobile stations.
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giantg2 • yesterday at 6:09 PM
I think there's other phenomena that people might be interested in such as E-skip and tropospheric ducting. Although you cant really rely on those.
VHF doesnt need line of sight, it has excellent ability to penetrate obstructions due to its long wavelength. For example, its not difficult to receive FM radio transmissions indoors, even from tens of km away. Some obstacles will effectively block any radio signal though, such as solid earth or concrete (esp rebar reinforced concrete).
You are right that handheld radios wont get more than about 10km, but that is due to the curvature of the earth. Mountain top to mountain top, you could easily do 50-100km