Compact Yagi Design for VHF?????????????????????????
 

Hi,

We would like to build our own Yagi from aluminum (better than
1/2" copper?) that can handle up to 400 watts or so.

We want to keep the antenna as compact as possible, but yet with
at least some directivity. I understand "compact" is a difficult
design parameter for VHF wavelengths, especially for a multi-element
Yagi, but that's what we want.

This would probably be a 3 element design, and it can be dedicated
for one frequency, or it can be broadband. There doesn't seem to be
too much design info on the web.

Any advice greatly appreciated.


Slick

two things you are missing... what frequencies, and just how compact is
compact?? a 3 ele yagi for 2m is only about 3' square, how much smaller
would you want it??

"Dr. Slick" wrote in message
om...
Hi,

We would like to build our own Yagi from aluminum (better than
1/2" copper?) that can handle up to 400 watts or so.

We want to keep the antenna as compact as possible, but yet with
at least some directivity. I understand "compact" is a difficult
design parameter for VHF wavelengths, especially for a multi-element
Yagi, but that's what we want.

This would probably be a 3 element design, and it can be dedicated
for one frequency, or it can be broadband. There doesn't seem to be
too much design info on the web.

Any advice greatly appreciated.


Slick

On Sun, 8 Feb 2004 12:07:21 -0000, "Dave" wrote:

two things you are missing... what frequencies, and just how compact is
compact?? a 3 ele yagi for 2m is only about 3' square, how much smaller
would you want it??

Physics and the wavelength will limit how compact you can get.

Also, this design is more selective not only in direction, but will
cover a narrower frequency range than a vertical.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

Gary S. Idontwantspam@net wrote in message . ..
On Sun, 8 Feb 2004 12:07:21 -0000, "Dave" wrote:

two things you are missing... what frequencies, and just how compact is
compact?? a 3 ele yagi for 2m is only about 3' square, how much smaller
would you want it??

Physics and the wavelength will limit how compact you can get.

Also, this design is more selective not only in direction, but will
cover a narrower frequency range than a vertical.


144 Megs. Just wanna make it as small as possible while retaining
directivity. Perhaps just a driven element and a director (no
reflector)?

I don't care if it's narrow-band.


S.

"Dr. Slick" wrote in message
om...
Gary S. Idontwantspam@net wrote in message
. ..
On Sun, 8 Feb 2004 12:07:21 -0000, "Dave" wrote:

two things you are missing... what frequencies, and just how compact is
compact?? a 3 ele yagi for 2m is only about 3' square, how much
smaller
would you want it??

Physics and the wavelength will limit how compact you can get.

Also, this design is more selective not only in direction, but will
cover a narrower frequency range than a vertical.


144 Megs. Just wanna make it as small as possible while retaining
directivity. Perhaps just a driven element and a director (no
reflector)?

I don't care if it's narrow-band.


S.

you still haven't said how small you think is small. 2 elements would be
about 18" by 36" with full size elements, which is plenty small for me.

On 8 Feb 2004 13:32:03 -0800, (Dr. Slick) wrote:

Gary S. Idontwantspam@net wrote in message . ..
On Sun, 8 Feb 2004 12:07:21 -0000, "Dave" wrote:

two things you are missing... what frequencies, and just how compact is
compact?? a 3 ele yagi for 2m is only about 3' square, how much smaller
would you want it??

Physics and the wavelength will limit how compact you can get.

Also, this design is more selective not only in direction, but will
cover a narrower frequency range than a vertical.


144 Megs. Just wanna make it as small as possible while retaining
directivity. Perhaps just a driven element and a director (no
reflector)?

I don't care if it's narrow-band.

You might take a peek at this product before you put too much time and
effort in:
http://www.arrowantennas.com/146-3ii.html

They also do ones for 70 cm and dual band, and can custom do ones for
a variety of frequencies.

The first reflector and director add greatly to performance, after
that the effect is less for each addition.

Compact in use and compact to carry are different things, think about
what you actually need.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

The fractal 2 meter quad would meet your needs.


"Dr. Slick" wrote in message
om...

144 Megs. Just wanna make it as small as possible while retaining
directivity. Perhaps just a driven element and a director (no
reflector)?

I don't care if it's narrow-band.


S.

On Sun, 08 Feb 2004 22:26:46 GMT, Gary S. Idontwantspam@net wrote:

Moxon Rectangle.........
Do a Google search for moxon rectangle + calculator