[TowerTalk] Help needed, antenna SWR

[n8de at thepoint.net]

If you are looking for 50 ohms at the feedpoint, the antenna you are  
using probably won't do it for you.
Most verticals (no matter how many radials are attached to that plate)  
will have a feedpoint impedance around 35 ohms ... thus the SWR you  
mention (50/35 = about 1.3)  If the feedpoint impedance is much less  
than 35 ohms, the SWR will be even higher.

Without a tuner placed AT THE FEEDPOINT, don't expect any 'magic' way  
to make all those antennas work at low SWR.

73,
Don
N8DE

Quoting Gary Smith <Gary at ka1j.com>:

> I did some spring maintenance on my antennas and need advice on how
> to get a 1.1 match.
>
> I have a radial plate with somewhere around 50 130' radials. I have 5
> wire antennas attached to this and use an Ameritron remote coax
> switch to select which antenna to use. There is a sloper for 160,
> INV-L for 80 and verticals for 40, 30 and 20. 17 & 24M are obtained
> by selecting either the 160 or 80M antennas. No tuner.
>
> I took the Antenna analyzer down to the antennas today and found 80M
> is SWR 1.8, 40 is SWR 1.9, 30M is SWR 2.35 to give some values. The
> lowest SWR I could get on 30M is 2.35 and the antenna is cut for the
> right length for minimum SWR at 10.100 MHz. This gives me the lowest
> SWR on the bands.
>
> I would like to get the SWR down as low as 1.1 at my desired
> frequencies If I can do so, but I'm not sure of the best way to do
> this. I suspect inductance from a coil at the individual feed points
> would work after I get the to SWR dip the lowest at the desired
> frequency but if this is the solution, what would be a good way to
> know do make such coils for each of the antennas?
>
> The antennas are 350 feet away, in the woods & onto a salt marsh and
> for me, right now, walking is very difficult to do and I want to make
> as few trips as possible.
>
> Suggestions appreciated.
>
> 73,
>
> Gary
> KA1J
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>