In article ,
says...


Bob Schreibmaier wrote:

Hi Tom,

In article , you say...

I haven't asked anything impossible or even tough, since I only gave a
general bound on size, gave the rough band limits desired, and said we'd
like gain and directivity.


Well... :-)

On a band that has a bandwidth of roughly 4% of
its center frequency, you're going to be REALLY
hard-pressed to get coverage of both phone and
CW on an antenna that is a little over 40% of
full size. So far, no manufacturer has been
able to come up with the antenna you describe.

Many years ago, Swan Antennas had a 2-element
40 meter beam that used half size elements.
As I recall, it used loading coils midway
through each element. I'm not very sure, but
I think the boom length was about 16 feet.
I think they got somewhere around 100 kHz
between 2:1 points. That wouldn't even cover
the entire phone band, and the elements are
longer than your design requirements.

So, yes, you are asking for something very tough,
if not impossible.

But, I wish you good luck in your quest! :-)

73,
Bob


From my original post -

"It would be desirable to have both CW and phone covered, but phone only
is ok."

From my original post -

I think they got somewhere around 100 kHz
between 2:1 points. That wouldn't even cover
the entire phone band, and the elements are
longer than your design requirements.

73,
Bob

--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+

"Tom Ring" wrote in message
.. .
I have a coworker that would like to put up a 40m antenna on his tower
that has some gain and directivity. I have modeled a few things, and
while they are fairly satisfactory, I wanted to see what ideas the group
had.

The approximate limitations are as follows -

o Boomlength 30 feet
o Element length 30 feet
o Any vertical components are max -10 feet from the plane of the boom
and elements. The reason here is that it's a crankup, and his roof
clearance would be about 10 feet when lowered.

It would be desirable to have both CW and phone covered, but phone only
is ok.
It will need to be coax fed.

Thanks.

tom
K0TAR

Check out the scans of the antenna he

http://home.earthlink.net/~rmowery28146/data/

It is from the 1981 Handbook. It is slightly larger than specified but may
be usable. The Files are about 1 and 2 meg in size.

Ralph Mowery wrote:


Check out the scans of the antenna he

http://home.earthlink.net/~rmowery28146/data/

It is from the 1981 Handbook. It is slightly larger than specified but may
be usable. The Files are about 1 and 2 meg in size.



Interesting, and a bit too big isn't a killer. I do not have a copy of
that Handbook. Is it available in any of the ARRL antenna books?

Meanwhile I'll check to see if I can find a copy of that.

Thanks
tom
K0TAR

Tom Ring wrote:

I have a coworker that would like to put up a 40m antenna on his tower

Thanks to everyone that responded so far. I have looked at most of the
ones suggested, and they are all interesting. Many were familiar, but I
looked again anyway.

The one I found most interesting in my personal search was from a link
someone posted a while ago. Here is the one I found off that link -

http://www.cebik.com/wire/4.html
and the antenna is "The VK2ABQ Square"

Does anyone have any experience with this?


I kind of expected someone to point to a dual driven element design of
some sort. Anyone have anything like that?

tom
K0TAR

On Wed, 23 Mar 2005 10:40:48 -0600, Tom Ring
wrote:

I have a coworker that would like to put up a 40m antenna on his tower
that has some gain and directivity. I have modeled a few things, and
while they are fairly satisfactory, I wanted to see what ideas the group
had.

The approximate limitations are as follows -

o Boomlength 30 feet
o Element length 30 feet
o Any vertical components are max -10 feet from the plane of the boom
and elements. The reason here is that it's a crankup, and his roof
clearance would be about 10 feet when lowered.

It would be desirable to have both CW and phone covered, but phone only
is ok.
It will need to be coax fed.

Thanks.

tom
K0TAR


Have you looked into the Moxon or X Beam designs? There is also a
drooping yagi where the elements of the yagi are fixed length, but a
wire is hung on the ends of the elements to keep the lengths of the
driven and reflector elements properly resonant. Additionally, you
can try linear loaded elements for the beam.

If it is small and directional, you better choose a portion of the
band and focus on that. I don't think you will find too many wide
band shortened beams.


--
73 for now
Buck
N4PGW