bpnjensen wrote:
On May 21, 5:48 am, Kevin Alfred Strom
wrote:
bpnjensen wrote:
On May 20, 10:32 am, bpnjensen wrote:
...and I'm gonna use existing trees to put it up about 30 feet above
ground, 15 feet above my rooftop on a 5x100 foot suburban lot. Power
lines both in front and back of my house, the ones behind are much
higher voltage, but not real high-tension wires.
All other things being equal, am I better off:
1 - Putting this thing up parallel to, or more perpendicular to, the
powerlines?
2 - Having the coax meet the wire at the base of the tree and
grounding it there, or running the coax up the tree and then depending
on the outer braid on the coax for ground purposes? The coax is
grounded at the first termination point at my MFJ antenna phasing unit
using a short, heavy copper wire to a ground rod.
Thanks,
Bruce
Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I
knew, some ARE new - I don't have a lot of room to experiment, but my
trees are situated so as to allow a generally perpendicular
orientation to the power lines, my main nemesis. Unfortunately, 30
feet is about as high as I can practically put them, but it's higher
than what I have now, so anything is an improvement, eh? Again,
thanks :-)
You're welcome.
Scaling the inverted L I described to half size -- 30 feet vertical
and 45 feet horizontal -- will still give excellent performance.
73,
Kevin, WB4AIO.
--http://kevinalfredstrom.com/- Hide quoted text -
- Show quoted text -
Thanks! Mine is likely to be 30 feet vert and about 65 feet horz.
Bruce
That'll work well, too.
Putting a few radials on the ground (or, even better, elevated a few
feet above the ground) connected to the coaxial feedline's shield
will help the low angle (most distant) reception.
Recent studies indicate that radials don't need to be a quarter wave
long for best results as previously believed, either. About 195
divided by the frequency in MHz (with the answer in feet) is near
ideal, but they will still help at any length.
I've used flat rotor cable with the conductors pulled apart, or
separated strands of telephone PBX cable, stapled to the grassy yard
with staples made from cut up coat hangers bent into a U shape and
hammered over the wire every five or ten feet. If it's done
carefully, you can mow over them the same day without problems.
After a few weeks, the grass buries them and you can hardly tell the
wires are there.
If I was going to build a new inverted L today, I'd elevate the
feedpoint and radials about seven feet for higher efficiency -- but
it would look a bit more obtrusive.
Good luck with the antenna,
Kevin, WB4AIO.
--
http://kevinalfredstrom.com/