On Sat, 12 Nov 2011 20:54:02 -0000
"Doug Turnbull" <turnbull@net1.ie> wrote:
>...some use inverted L antennas of 160 feet
>plus in length and
> others like myself have them closer to a quarter wave
Doug,
You had a great signal here in Miami the other night, so
I think your antenna works well (enough). So don't rush
out to lengthen your inverted L just yet :-)... But...some
believe that a longer antenna will move the current
maximum higher, away from the lossy ground.
As others on this reflector have pointed out, when a
buried, or on the ground, radial field is insufficiently
dense to shield the antenna's H field from the ground, the
resulting eddy currents through the (less then perfect)
ground will result in losses. The less of the field is
intercepted by the ground, the lower these losses. Hence
the idea of moving the current maximum -- and thus the
field maximum -- up.
I have done some informal testing comparing a 1/4 wave
vertical with an almost 1/2 wave vertical and found that
the longer antenna put out a stronger signal. So there may
be something to this theory... Of course, with an inverted
L you do not want to move the current maximum into the
horizontal section, so the antenna should not be too long.
73,
George, AA7JV
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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