Roy, ruling out quad loops and multi element antennas what do we have
available? I like the idea of working both LP and SP to the US but if you
have an idea for a wire antenna supported by only two ropes I would consider
that. What would the pattern be like for a bobtail with extra vertical
elements spaced the usual half wave? With the trees I have in mind I could
possibly fit in six vertical elements.

Thanks es 73 Alan


"Roy Lewallen" wrote in message
...
The problem you'll run smack into with any fixed antenna is that to get
gain in one direction you've got to take away gain in others. So the first
thing you have to decide is which directions do you want to improve your
signal in, and which are you willing to sacrifice. Then consider where
your trees are. Only then can you begin to consider what kind of antenna
might deliver what you want.

Roy Lewallen, W7EL

Alan Taylor wrote:
I have some space and some high trees. I already use a 400ft doublet with
atu for several bands and a 30m half square and get good results. I want
to improve my performance on 17m. I am now thinking about a wire
antenna with reasonable performance for 17m only. I have thought about a
full wave loop, even a bobtail. A broadside array would be great but I
am not keen on antennas with reflectors or directors because of the
complexity of support ropes. So, really some kind of antenna supported by
ropes from two trees would be ideal. Any ideas please?

Alan VK6BN

Since you are supporting a 30 meter vertical, I suspect that you can
support a 17 meter half wave vertical.. A halfwave, bottom fed,
monopole, worked against an elevated counterpoise... Said elevated
counterpoise to be a half wave in length, and tapped at it's
centerpoint... Two or three feet off the ground will work, while head
high would be nice...
A single antenna will give 360 coverage... Two, three, or four of these
with switching to rotate the pattern will give you gain in given
directions, while still allowing 360 coverage...

denny / k8do

Alan Taylor wrote:
Roy, ruling out quad loops and multi element antennas what do we have
available?

Thanks es 73 Alan

Alan Taylor wrote:


Alan Taylor wrote:
I have some space and some high trees. I already use a 400ft doublet with
atu for several bands and a 30m half square and get good results. I want
to improve my performance on 17m. I am now thinking about a wire
antenna with reasonable performance for 17m only. I have thought about a
full wave loop, even a bobtail. A broadside array would be great but I
am not keen on antennas with reflectors or directors because of the
complexity of support ropes. So, really some kind of antenna supported by
ropes from two trees would be ideal. Any ideas please?

Alan VK6BN

The EDZ is the easiest I suppose. About 5.1 dbi/3dbd if I remember
right.
You could run two half wave dipoles, spaced a half wave apart
with rope. Feed in phase. Also good for about 3dbd. The lazy H
antennas could be run between two trees. Too bad you can't run a
yagi. That what you really need.. Or at least the most bang for it's
size,
and it can be steered. Also, I guess you could run a larger franklin
type
array. IE: 3 or more 1/2 wave elements. BTW, you also can use
"extended"
lazy H type arrays where the elements are EDZ length. Gives more gain
than the usual 1/2 wave lengths.
MK

Alan Taylor wrote:
Roy, ruling out quad loops and multi element antennas what do we have
available? I like the idea of working both LP and SP to the US but if you
have an idea for a wire antenna supported by only two ropes I would consider
that. What would the pattern be like for a bobtail with extra vertical
elements spaced the usual half wave? With the trees I have in mind I could
possibly fit in six vertical elements.

Of course, what I'd recommend is that you model some of these antennas
with a program like EZNEC. The free demo program is adequate for some of
the antennas you're interested in. The demo program is able to model
some more complex arrays with quite an accurate pattern -- what suffers
is the accuracy of the reported feedpoint impedance.

One antenna you might consider is the "Field Day Special"
(http://eznec.com/Amateur/Articles/Fi...y_Special.pdf). It has two
elements, but can be suspended with two ropes by using spreaders made
from PVC pipe or other light weight material. The advantage to this
antenna over some others is that it has a unidirectional pattern which
is easily and instantly reversible. With a unidirectional pattern, you
get a broader beamwidth for a given amount of gain, compared to a
bidirectional array. It also reduces QRM off the back, but of course you
get more to the sides of the broadside direction since the beam is wider.

Roy Lewallen, W7EL