[NLRS] Is there published data on tree foliage ...

[Jon Platt via NLRS]

Another source of interest is ITU-R P.833-5 titled Attenuation In Vegetation.   The paper does include a table that shows "attenuation through woodlands" in dB/m vs frequency.   In their work they found a different attenuation rate for vertical vs horizontal polarization below 1 GHz stating that this was perhaps due to trees trunk. 

Here are some eyeballed values off the table.

Freq            -----  dB/m ------
  50            0.01 (H)    0.03 (V)
144            0.03 (H)    0.06 (V)
432            0.09 (H)    0.15 (V)
1 GHz          0.2
10 GHz        2
24 GHz        5

No comments on wet vs dry but they do say these are ball park numbers that vary significantly based on the type of trees and whether they are leafed out or bare.   Also they talk about increased attenuation when they are moving due to wind  ..... foliage movement increases attenuation.

73, Jon
W0ZQ

 
Register for the CSVHFS conference on July 25-26th at: 
http://www.csvhfs.org/2014conference/index.html