"Cecil Moore" wrote in message
. net...
James barrett wrote:
Hi, I don't understand how you can add elements to an existing antenna
and have it still work on the band it was originally made for. Do you
still need a tuner? Or do you remove the 20m elements to transmit on
10m?

The RF source energy will follow the path of least
impedance. If we have dipole elements for 40m, 30m,
and 20m on the same antenna, when we are on 30m, for
instance, the 30m dipole has a low impedance while
the 40m and 20m dipoles both have high impedances
to the 10.125 MHz source signal. This configuration
can function without a tuner.

.... and it does for me on 20 and 10. I don't know how many sets of dipole
elements can be connected at the same time, but I think it's more than the
two I have up there now. Richard gave the number five. That's why I said
I'm going to try a set for 40m.

On Wed, 28 Nov 2007 22:54:55 -0800, "Sal M. Onella"
wrote:

... and it does for me on 20 and 10. I don't know how many sets of dipole
elements can be connected at the same time, but I think it's more than the
two I have up there now. Richard gave the number five. That's why I said
I'm going to try a set for 40m.

You are going to give Art apoplexy by crediting me!

Better to back off from my 5 and instead consider:
http://home.comcast.net/~kb7qhc/ante.../Cage/cage.htm
which comes to the same thing, but not at the expense of forever
re-tuning each wire by band.

Either way, you have to love stringing wire....

73's
Richard Clark, KB7QHC

Sal M. Onella wrote:
... and it does for me on 20 and 10. I don't know how many sets of dipole
elements can be connected at the same time, but I think it's more than the
two I have up there now. Richard gave the number five. That's why I said
I'm going to try a set for 40m.

A fan dipole with elements for 40m and 15m doesn't
work well because of the resonant interaction
between those two elements of 0.5WL and 1.5WL.
Most hams I know use the 40m dipole also for 15m
operation with a tuner.
--
73, Cecil http://www.w5dxp.com

In message , Cecil Moore
writes
Sal M. Onella wrote:
... and it does for me on 20 and 10. I don't know how many sets of dipole
elements can be connected at the same time, but I think it's more than the
two I have up there now. Richard gave the number five. That's why I said
I'm going to try a set for 40m.

A fan dipole with elements for 40m and 15m doesn't
work well because of the resonant interaction
between those two elements of 0.5WL and 1.5WL.
Most hams I know use the 40m dipole also for 15m
operation with a tuner.

It may not work in the same manner as the paralleled dipoles for the
other bands do (ie where only one dipole is active at any one band).
But, of interest, do paralleled 40m and 15m dipoles actually work
'badly' on 15m? Obviously, the feed impedance and the radiation pattern
are likely to be a bit different, but (maybe with a tuner to help tune
things up a bit better) would the overall performance still be poor?
After all, the RF you put into the antenna has to go somewhere (even if
it's not where you expect it to be).
--
Ian

Ian Jackson wrote:
But, of interest, do paralleled 40m and 15m dipoles actually work
'badly' on 15m?

When I said it "doesn't work well", I meant that it doesn't
work like a single predictable dipole. If the 40m dipole
soaks up a lot of the RF energy on 15m, the radiation pattern
will not be the predictable figure-8 broadside 1/2WL dipole
pattern. It may be more of a multi-lobed cloverleaf radiation
pattern. If one aims a 40m dipole broadside to the desired
contact point and uses it on 15m, it "doesn't work well".
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Ian Jackson wrote:

When I said it "doesn't work well", I meant that it doesn't
work like a single predictable dipole. If the 40m dipole
soaks up a lot of the RF energy on 15m, the radiation pattern
will not be the predictable figure-8 broadside 1/2WL dipole
pattern. It may be more of a multi-lobed cloverleaf radiation
pattern. If one aims a 40m dipole broadside to the desired
contact point and uses it on 15m, it "doesn't work well".


What would you consider the best direction to hang a long dipole? I will
be hanging about 135 feet with the ends at east and west. It's the only
direction I have enough room to hang a wire antenna that long.


Jim

James Barrett wrote:
What would you consider the best direction to hang a long dipole? I will
be hanging about 135 feet with the ends at east and west. It's the only
direction I have enough room to hang a wire antenna that long.

It depends upon what you want your radiation pattern
coverage to be from your particular QTH. I orient my
130 foot dipole so that my radiation lobes point toward
the world's large land masses on 20m. The free demo
version of EZNEC available from eznec.com will tell you
what direction your lobes are pointing.

The radiation patterns for an east-west 130 foot dipole
can be found on my web page under my notuner all-HF-band
antenna design. The 20m radiation pattern is at
http://www.w5dxp.com/20m.htm
--
73, Cecil http://www.w5dxp.com

http://stockton.craigslist.org/ele/488204046.html

JS

Cecil Moore wrote:
It depends upon what you want your radiation pattern
coverage to be from your particular QTH. I orient my
130 foot dipole so that my radiation lobes point toward
the world's large land masses on 20m. The free demo
version of EZNEC available from eznec.com will tell you
what direction your lobes are pointing.

I tried using the demo version of EZNEC, but haven't figured it out yet.
I don't really know yet what I want my radiation pattern to be because
I've had an HF radio now for three weeks, and only a 10 meter dipole.
(tuner to be delivered this weekend). Of course I have made no contacts
on 10 meters. I tried CW on 15 meters (yes, on my 10 m dipole with no
tuner, at low power) but no one has answered. Probably because of my
slow wpm. ;-)

Anyways, I'm not sure yet what to expect as far as making contacts.
Would I have a better shot from east or west, or would I have a better
shot north and south?

Well, before I go too far off topic, I read ch. 7 from the ARRL Antenna
book, and I think the best for me as far as antennas go, is the 135 foot
dipole fed with 450 ohm window line, and it will have to go east/west
which means I might be talking to Santa this year! ;-)

So, I guess what I should have asked was, what would be the best
orientation for a dipole in New England in order to make contacts at
this time of year and at this point in the sun spot cycle.

Ok, having said all of that, I have some ideas for shorter dipoles that
can hang north/south. So there is much experimenting in my future. :-D

Busy weekend, be listening for me on cw!


Jim
kb1odg

James Barrett wrote:
I tried using the demo version of EZNEC, but haven't figured it out yet.

Time to diagnose that problem. :-)

Anyways, I'm not sure yet what to expect as far as making contacts.

At this low of the sunspot cycle, don't "expect" anything
above 14.35 MHz to work. :-) 40m CW is my favorite band
right now.

Ok, having said all of that, I have some ideas for shorter dipoles that
can hang north/south. So there is much experimenting in my future. :-D

Hang your long dipole E/W. Hang another dipole in parallel
N/S as long as you can make it. Use an antenna tuner. Enjoy,
i.e. put something in the air and be patient.
--
73, Cecil http://www.w5dxp.com