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Topband: Trees And RF - Suggested Test

To: "Top Band Reflector" <topband@contesting.com>
Subject: Topband: Trees And RF - Suggested Test
From: "Ward Silver" <hwardsil@gmail.com>
Reply-to: Ward Silver <hwardsil@gmail.com>
Date: Tue, 3 Nov 2009 08:36:25 -0800
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I suggest the following tests to be done by someone else than me...any of which 
could give us some anecdotal evidence about trees and RF, at least.

Wind a several-turn solenoidal coil with a diameter large enough for a section 
of tree to be inserted. Measure the inductance and the Q with and without the 
branch inserted.  Significant changes in the L or Q (at RF) would indicate 
interaction between tree and field.

Make a vertical dipole and suspend the top from a pulley that can move along a 
non-conductive catenary (i.e. - a rope) between two trees at least one-half 
wavelength apart.  Measure the resonant frequency and SWR bandwidth of the 
dipole when suspended in the middle of the catenary.  Move the dipole closer to 
the tree in steps of about 0.1 wavelength, repeating the resonant frequency and 
SWR bandwidth measurements at each step.  Significant shifts in either resonant 
frequency or increases in the SWR bandwidth indicate interaction between tree 
and field.

Have at it - that would make a nice QST or QEX article!

73, Ward N0AX
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M

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