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



And also from my original post

"o Boomlength 30 feet
o Element length 30 feet "

which is a whole lot more than 16 feet.

But you are probably correct. It's impossible.

"Tom Ring" wrote in message
.. .
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



And also from my original post

"o Boomlength 30 feet
o Element length 30 feet "

which is a whole lot more than 16 feet.

But you are probably correct. It's impossible.


Check out the Optibeam Moxon rectangle. I think its boom length is something
like 20 feet. Also, the Moxon Antenna Project web site has a program for
calculating the various dimensions.

Paul AB0SI