On Mon, 19 Mar 2007 20:28:44 -0500, "merlin-7"
wrote:
A question for you experts out there...
I currently use a fan dipole (kind of a fan anyway)
SNIP
What are the pros and cons of fan dipoles like this? I have never heard of
a fan dipole with each element being hung under each other so I have no data
to compare it to.
I haven't used the inverted-V formation, but I have used the
multi-band parallel dipole since I was first licensed in 1978. The
pros are that if the elements are 8" or closer (I never ran them
further apart), I get a broader bandwidth per band. (That comes in
handy on 80 & 40 meters. ) you don't need a tuner for the three bands
of your choice (adding more wires means additional bands). If you are
a cw buff, the 40 meter dipole also doubles as 15 meters.
The cons are that the antenna isn't very stealth (if that is an
issue.), if you are running an amplifier, you could be radiating the
harmonics more efficiently. It could get tangled in the wind or limbs
of a tree (I had to deal with that and place spacers closer together.)
I have never noticed a difference in the Multi-Band Parallel Dipole
MBPD (just what I call it, probably not an official name) and a mono
band dipole as far as signal strength goes. I can't model one in my
program as it thinks that is one big fat wire.
I would like to keep this set up when I move to my new QTH in a few months
but raise it to 60 feet or so.
The higher the better...
I really do not wish to put up a wire for each band as the one I have now
can run everything from 10m to 80m and even the low side of 160, right
around 1.8 mhz (I havent figured that one out yet)with a tuner.
80 should be a close double for 10 and 60 meters, 40 doubles with 15
meters and some combination of left and right wires double for the
other ward bands (I suppose - wag) unless 80 tunes for it. I don't
know about 160 as I have never tried to tune one to it.
What are the pros and cons of adding more wires? (other than tuneing the
wires being more of a pain)
Pros: instant switch to more bands without having to use tuner,
Cons: more harmonic risk, more wind load, more visible wire, more
weight, more expense.
I get very little interaction between the wires (maybe due to the fact they
are spread apart so close to the feed point) or I just got lucky, hi hi
I am looking for ideas or someone that is great with an antenna program,
that can tell me what my antenna is doing now and how to improve it at
around 60 feet at the feed point.
It looks like my shack will be up befor my new home will be ready (solar
power has its advantages) So I need to plan the antenna and the mounting
points for the ends of the wires.(angle or slope) in other words, how high
the ends need to be.
I plan on placeing the wires east / west broadside but would like a bit of
an omni pattern to reach the east coast(NY to FL) from jacksonville NC.
Sorry for the long post but I know of a few out there that can give me some
ideas that I have overlooked. It is better to plan ahead .....
Thanks
Joe
KI4ILB
I don't know what the radiation pattern will look like, but I suspect
it will be pretty much round. I would think, for the effort, it might
be well to put up two antennas, each with either three or four bands.
I mostly used 4 bands, each additional wire gets considerably more
difficult to deal with. I usually design them and space the wires
with PVC pipe which means I have to cut the pipe and add all the wires
at once or create a whole new antenna at the end.
Personally, I use #14 THHN wire which is coated and can be purchased
in various colors. I could choose different colors for each band if I
like. However, the noise factor during winter weather (ice, etc.) if
I keep them all insulated. I found that if I spaced the wires 8
inches apart, I get to reverse engineer the formula for adding bands.
This means I trim out the ten and 15 meter bands (I didn't use this
for ward bands) and then reverse engineer the formula...
x/F=L
x=468, F=Frequency in MHz, L=length in Feet.
L*F=x
Next, calculate with the new x for the additional band you desire to
add. This will narrow your trimming down to a minimum.
Good luck, I am looking forward to reading all the replies.
Buck
N4PGW
www.lumpuckeroo.com
73
--
73 for now
Buck, N4PGW
www.lumpuckeroo.com
N4PGW