Tree Attenuation

[NECRAT]

Has anyone ever calulated what the signal attenuation on a FM signal is based on tree density. Meaning if you have a station who's transmit antenna is below the tree canopys, what the loss to the coverage area equates to?

Which brings up a 2nd question. I am going to give a "for instance" here. If you have a 50 watt radio station, who's antenna is below the tree line, what benefits, if any, do you have by going above the trees, even if it means you drop in power, lets say to 25 watts. Do the trees attenuate a small signal enough that by raising the antenna above the tree line w/ reduction of power, is very benificial...

[Deep Thought]

I don't have even any empirical evidence to prove it (it'd be almost impossible around here anyway being in a huge urbanized area) but I do know that 20 years ago you could pick up 92.7 in Arlington Heights, IL a lot better in La Grange and Downers Grove, IL in the winter than in the summer, a line of sight distance of around 25 miles. The only difference was the trees. Back then they ran 3 KW at about 260 feet.

[kcbooboo]

You would also have to compare dry leaf attenuation vs wet leaf attenuation. I know that UHF repeater signals are weaker and the multipath interference is much greater when the leaves are in full bloom and wet, than in the winter when most have fallen off. This is from a TX antenna that's way above the tree line, but the RX antenna is below it.

Bob M.

[RGORJANCE]

I wonder how much of that signal degradation could be due to temperature inversions. I know of several stations scattered around Wisconsin that have that happen very frequently during the summer. The Kenosha FM in particular at times cannot be heard in the downtown area which is next to the "big pond".

Fossil