Joe posted,
I moved my 160 inverted L to a tall tree in my backyard to get more
vertical height. The vertical leg is now about 65 feet and the rest
(65feet) is horizontal. I fed this one with about 125 feet of 75 ohm coax
just because I had lots of it laying around. No tuners, baluns, ununs or
chokes in the feed line. The ground is connected to the existing ground
system for the old L. I get a 1.1 SWR reading from 1.8 to 1.9 before it
moves up to 1.3 and slightly higher to 2.0. The antenna seems to be working
OK (relative to the old L). This seems awfully broad banded? Any feedback
would be great. Thanks -Joe N3HEE
and Joe added:
The antenna feed point terminates at a four foot ground rod and then I am
running a number 14 wire from that ground rod to my existing radial field.
That run is about 40 feet. The radial field consists of 3 8 foot ground
rods and nearly 2000 feet of wire spread out over my entire front and back
yard. I didn't want to run "new" radials over top of the existing so that's
why I did what I did. I am measuring SWR from the shack end of the feed
line>>>
Unfortunately there is almost no radial system ground connection at all on
the new inverted L, because there is almost 1/8th wave of a single thin wire
between the real ground and the feedpoint.
That wire length, 40 ft, could add hundreds of ohms impedance to the ground
path.
While bandwidth is a terrible way to guess efficiency, it is also obvious
the ground radial connection really isn't a worthwhile connection at all.
73 Tom
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