Wayne wrote:
wrote in message ...
Wayne wrote:
wrote in message ...
wrote:
On 1 May,
wrote:
# I was refering to the case where there is nothing to adjust the match
and
# getting something under 3:1 at the end of the feed line.
#
# Given an ATU, you can usually match anything and there is no need for
the
# physical complexity of a fan dipole.
An open wire fed dipole would give pretty good performance. But, feeding
such an antenna with RG-8 and living with a high VSWR (maybe up to 10:1)
shouldn't be discarded.
A dipole of about 18 feet would cover 24 and 28 MHz with about 5:1
VSWR....not bad.
# My transmitter gives up at about 5:1.
# Your milage (and transmitter) may vary.
Yes. My Yaesu ATU gives up at 5:1, so I have been using a more robust
homebrew tuner.
A VSWR of up to say 10:1 (perhaps 15:1) shouldn't be a deal killer, if you
can match the coax and are willing to accept 2-3 dB of loss. This opens up
a lot of antenna possibilities that might be otherwise discarded.
Well, my trap inverted vee for 40-30-20-15-10 has a SWR of less than 2:1
where all my interests lie, and less than 1.5:1 on most bands.
Then there is the vertical that currently covers 160-10 at less than 1.3:1
on all frequencies for the days when I want to do something different.
It started out as about 33 feet of tubing for 40.
Wanting more, I built an enclosure containing a pair of relays and loading
coils so it was less than 2:1 on the areas of interest on 160 and 80.
Wanting more, I mounted a SGC autotuner at the base so it is always 1.3:1
or less on all bands.
EZNEC analysis says the lobes are low, and actually have some low angle
gain on 15 and 17, until I get to 12 and 10, where the lobes start pointing
to the sky.
The next modification will likely be finding a 10 M trap at a swap meet
and installing it at about 5/8 wavelengths to push the 10 M lobe down.
I can live without perfection on 12.