QST Article – “Live Trees Affect Antenna Performance” – implications for #POTA #SOTA
Wayne Robertson, K4WK, is a regular contributor to AmateurRadio.com and writes from Georgia, USA.
In February 2018’s QST was a very interesting and scholarly article, the cover story actually, on the effects of live trees on the performance of both vertical and horizontal antennas. Things to ponder:
- Living wood (trees, as opposed to dry dead wood such as boards) absorbs EMF from vertically polarized antennas.
- Living wood resembles human tissue in terms of dielectric properties, so wearing your HT on your belt will greatly reduce your effective antenna power. Presumably, unless you’re a real fathead like me, talking into HT held at your face should not be too bad.
- A single vertical tree has next to no effect on horizontal antennas, such as dipoles.
- A forest, containing lots of vertical trees, is even worse than a single tree like in your backyard, so for us backpackers and hikers, we need to find a clearing when trying to use our HT’s in the woods.
- Worse, a forest will affect both vertical and horizontal antennas so when we’re operating in the field, for POTA or SOTA for example, we should look for a Goldilocks spot with enough trees to launch the, say, dipole, but not too many. Better in Winter after leaves fall, though.
This is Wayne, k4wk, http://www.hamdom.com. Thanks for listening; you’re in the log.
I always knew that forests affect VHF/UHF propagation, but this an interesting addition to this knowledge. Thanks!
I get on 1296 MHz every Monday night (cw / ssb) and I’m shooting through the trees in most directions. Summer q’s are usually down 1 1/2 or more s-units over winter, presumably because of the leaves.
why can’t i join amateur radio.com this information is correct. thanks