Hi group,
just wondering.... can I take a 40M delta loop and add an 80M dipole to it?
Will there be interaction?
SWR problems?

Mark W4UDX

Mark,
Yes, to both.
'Doc

wrote:
just wondering.... can I take a 40M delta loop and add an 80M dipole to it?
Will there be interaction? SWR problems?

Actually, that should work pretty well. A loop has a very high
impedance on half its design frequency. Another thing to consider
is breaking the 40m loop opposite the feedpoint for operation on
80m. 1WL on 40m = 1/2WL on 80m.
--
73, Cecil http://www.qsl.net/w5dxp



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just wondering.... can I take a 40M delta loop and add an 80M dipole to it?
Will there be interaction? SWR problems?

Why not just increase the size of your loop to make it an 80 meter loop?? That
should cover 40m, at least thats what I've read...I'm in the process of
building my 80 meter loop which will hopefully work 10-80...Good luck..

Steve

"Desmoface" wrote in message
...
just wondering.... can I take a 40M delta loop and add an 80M dipole to
it?
Will there be interaction? SWR problems?

Why not just increase the size of your loop to make it an 80 meter loop??
That
should cover 40m, at least thats what I've read...I'm in the process of
building my 80 meter loop which will hopefully work 10-80...Good luck..

Steve


But remember a loop for 80 fed with coax will make for a high impedeance on
40.

If you feed this 80 meter loop with ladder line, open wire line, etc. You
can use it everywhere via a balanced output tuner of course.

Dan/W4NTI

Dan/W4NTI wrote:
But remember a loop for 80 fed with coax will make for a high impedeance on
40.

Higher, but not too high. A 2 WL loop is resonant in much the same way
that a 1 WL loop is resonant. Perhaps you are thinking about dipoles?
--
73, Cecil http://www.qsl.net/w5dxp



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"Cecil Moore" wrote in message
...
Dan/W4NTI wrote:
But remember a loop for 80 fed with coax will make for a high impedeance
on
40.

Higher, but not too high. A 2 WL loop is resonant in much the same way
that a 1 WL loop is resonant. Perhaps you are thinking about dipoles?
--
73, Cecil http://www.qsl.net/w5dxp

Two things to consider he

1. If you cut it for 3850, as an example, it will be way out of band on 40
meters (7700).

2. If you match it with a 1/4 wave section of RG11 on 80 meters, that will
be 1/2 wave on 40, and have no effect.

Having said all that, I find my Ameritron amp with a pi network output will
tune up on 40 meters. My loop is resonant at about 3800. Just in case, I
keep the power down.

Tam/WB2TT

But remember a loop for 80 fed with coax will make for a high impedeance on
40.

Yeah, you'd probably need to use a tuner but one wavelength on 80 is 2
wavelengths on 40, is 4 wl's on 20, 8 on 10....theoretically an 80 meter loop
should work great on 10-80 and the take off angle supposedly decreases as the
frequency increases...so it should be good at dx too..

Steve
kb8viv

On Fri, 31 Oct 2003 19:30:49 -0500, wrote:

Hi group,
just wondering.... can I take a 40M delta loop and add an 80M dipole to it?
Will there be interaction?
SWR problems?

Mark W4UDX


Hi Mark and All,

your Idea of adding a dipole to you 40 meter loop is not a great way
to go.. there will be interaction between the dipole and the loop.
that will cause you problems on both bands.. The better approach would
be to feed the loop with open wire through a good balanced tuner and
feed it on both bands.. on 80m for a 40 m loop you may have to open
the loop opposet from the feed point . If you have room however to
put up a 80 Meter horizontal loop and feed it with Open wire ( Ladder
Line) it will play very well on all bands 80-10m.

Remember a Horizontal loop will get better take off angel as you move
up in frequency. a vertical loop gets worse as you move up in
frequency. (that is higher take off angles) I used a 160M horizontal
loop here for many years .. until a storm took down too of the trees
used for support. But it was a good all round antenna.

73 Dave kc1di

P.S. you may want to read up on loops here's a good place to start.
http://www.cebik.com/vdelt.html

http://www.cebik.com/atl1.html

http://www.cebik.com/fdim/fdim5.html

Mark,
On 40meters, adding an 80 meter dipole to the 40 meter
loop won't 'mess' things up much. It'll change the radiation
pattern, make it sort of directional, kinda. No big deal.
But, on 80 meters, the 40 meter loop acts like a 1/2 wave
'short' between the two halves of the dipole. SWR goes up
close to around 500:1, the transmitter is looking at something
on the order of '300R - 2500J'. Not too good, and as for the
lower radiation angle, it really doesn't make a lot of
difference
at that point.
'Doc

PS - The 'numbers' are approximate, "close enough for 'gum-ment'
work"...