[TowerTalk] Re 80M Antenna Challenge

[Dennis W0JX]

Steve,
My lot is heavily wooded and I use wire verticals on 80, 40, and 30 meters. On 160M, I shunt feed my 80 foot tower. Some of trees go up to 115 feet.
I have two 40 meter wire verticals, a ground plan and a "Half Square." Initally I had one end of the Half Square suspended from the tower and the other by a tall cedar tree. It showed 4 to 6 db advantage over the 40M ground plane (which hangs from a very tall tree branch.)
The Half Square was affecting the tower match on 160M so I moved the Half Square to some tall trees away from the tower. The result, confirmed by numerous comparative signal reports, and PSK reporter, shows at least a one S unit deficit to the previous location away from the tall trees.
Secondly, the SWR was affected. Before the weather turned cold, the Half Square SWR was about 1.6 to 1 (fed at an upper corner). Now with colder weather and falling leaves, the SWR has dropped to 1.2 to 1.
In summary, I suggest keeping the vertical wire as far away as you can from the trunks of tall trees. I believe that tall trees are definitely detrimental to the operation of low frequency transmit verticals. I also see this affect on my shunt fed 160M tower as the trees leaf out in the spring and lose their leaves in the fall.
73, Dennis W0JX