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M=2E van Wijk (incl) wrote: Hello, I just moved to a new location. My backyard has some 20 trees spread around at a distance of 5 to max 10mtrs between each of them. I would like to opt for a full size 40mtr(7Mhz) vertical and have (only)the 2 following options her: 1) full size 1/4 wire vertical inside fishing pole, mounted in a tree at a foot height between 7 and 10mtrs from ground level. Some 4 elevated radials will be added. 2) full size 1/4 wire vertical at ground level, parallel to a tree at a distance of 0.5 till max 1 mtr. Ground screen will be some 16 pcs of wire buried in the surrounding ground. I have no clue about any effects of trees here. They are not pine trees. There are lots of other parameters in the whole picture, but the trees is a totally unkown factor for me. Please share me your experiences. Thanks in advance. You might consider a simple inverted L given all the trees you have available. Build a very conventional half-wave coax-fed 40M dipole. Suspend half of it (35 feet long?) vertically with the lower end a foot or two above the ground from one tree then pull the other half more or less horizontally to another tree. Pull the coax away from the elevated feedpoint toward the Radio Room. Trim wires to resonance. No messy radials needed and most likely you wouldn't need a tuner or "tuning network" either. It would be just a standard inverted vee rotated 45=BA. Half-wave inverted Ls without radials scream, been there, done 'em. Research on the subject done by the U.S. Army years ago determined that trees have no measurable effects on HF antennas. Trees do have an effect on vhf/uhf antennas. There was a thread in this NG in the past which addressed the topic in sdome detail and which is probably still archived. Run a search on "Do Trees Absorb RF?" =20 '73 Mark, PA5MW w3rv |
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Buck wrote: Since he has room to hang a vertical, he can hang a slanted dipole too. That would be a little directional but pointed in the right direction it could be a great antenna. OOPS! forget my last.... (remember to engage brain before fingers.) Heh. We all do it. "Welcome to da club." -- Buck N4PGW w3rv |
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