On Sun, 27 Jan 2013 22:34:35 -0500, "Ralph Mowery"
wrote:


"Jeff Liebermann" wrote in message
.. .
On Sun, 27 Jan 2013 10:53:41 -0500, "Tom" wrote:

But I want to hear some positive ideas. How can I make this work for 2m
and
70cm. I don't want a 10m omni.

You would probably do better loading a step ladder. However, if you
insist, you can load just about anything if you can find a 50 ohm tap
point with a gamma match. Attach a connector ground to the bottom of
the element with a hose clamp. Put another hose clamp further up the

The step ladder probably will work just as well as the full wavelength
vetical. More than likely the radiation patern will be vertical and only
good for working OSCAR.

Well, the step ladder antenna came from what appears to be a
fabrication, where a loaded step ladder allegedly won an ARRL
sponsored antenna construction gain competition. I have my doubts,
but it was a good story. In the best Mythbusters tradition, I
produced a crude model of a fiberglass extension ladder section with
4NEC2 to see what could be done. I selected fiberglass because the
insulating fiberglass would not short the aluminum ladder rungs. At
this point, it's only a model and I haven't actually tested more than
the driven element matching.

If you don't mind, I would like to keep the details of how I did it
secret as I was considering writing an article on the topic.

As it is well known you can match just about anything to 50 ohms but that
does not mean it will radiate or atleast radiate in a desirable direction.

Yep.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

In article ,
"Tom" wrote:

Any reason why I shouldn't shorten this ringo I have to 6ft 4in (full
wavelength for 2m) ? Any reasons why I shouldn't use the gnd planes? How
long should they be for that length omni?

Tom-

The reason you do not want a full wave antenna like this, is that it
sends much of its energy up towards the sky instead of towards the
horizon. The 5/8 wave antenna sends the maximum amount towards the
horizon.

You could stack a half wave antenna on top of a 5/8 wave antenna with a
proper phasing network. That might improve your signal towards the
horizon.

Using radials for a ground plane is a good idea. I would make them each
a quarter wave long.

Fred
K4DII

Thank you all for the information,

Very interesting, I am not very good with the golden screwdriver, more of an
appliance operator but love challenges and learning.

Appreciate every word of your expertise.

This project will fly. Now I am studying coax because I will go down to the
local supplier (25miles to the only supplier locally) for some coax. This
has been the discussion on our local vhf band. You chaps would love it or I
wish you were in the chats. Everyone around here has different ideas on
coax. I wont open that can of worms but all I can find available is the RG8U
that is 13 awg center. Hard foam insulation with foil and then 95% braiding.
This coax is a bit larger o.d. which makes it a much much tighter and
snugger fit into the ends. Actually it is the only product around, little
pricy at .45 Cents per foot. I like its size, I didn't want that big think
bulky coax because I always run QRP and like the flexibility and
availablility. I been reading all the charts that show so much loss at so
many feet at which ever frequency at what ever power. All trivial for me
because minimal, all important for you guys with your calculations,
engineering, long lengths and designs for commercial or military or maximum
efficient uses.

I think I have a winner with this coax that is really all I can find
locally, I was wondering about that 13awg center, stranded. Everywhere else
seems to be 18 ga or 20 ga. All thinner. My line of thinking is that I
already have the 13ga in my system. I made a bunch of jumper from it, the
short pieces from rig to tuner or meter, so I wanted to keep it all the same
guage.

Am I thinking this out properly? Can you gents tell me your thoughts on
coax? I don't need to know how its made, just recommendations or suppliers
who sell online the best stuff. I appreciate your expertise.

Thanks

73s





"Fred McKenzie" wrote in message
...
In article ,
"Tom" wrote:

Any reason why I shouldn't shorten this ringo I have to 6ft 4in (full
wavelength for 2m) ? Any reasons why I shouldn't use the gnd planes? How
long should they be for that length omni?

Tom-

The reason you do not want a full wave antenna like this, is that it
sends much of its energy up towards the sky instead of towards the
horizon. The 5/8 wave antenna sends the maximum amount towards the
horizon.

You could stack a half wave antenna on top of a 5/8 wave antenna with a
proper phasing network. That might improve your signal towards the
horizon.

Using radials for a ground plane is a good idea. I would make them each
a quarter wave long.

Fred
K4DII