"Richard Clark" wrote in message
news
On Tue, 29 Aug 2006 11:27:10 GMT, "Lee"
wrote:

Yes, thanks for the info but i would like a little more gain than a
standard
discone gives...going to a parabolic discone would be the alternate
option
but a little too involved....

Parabolic discone??!!!?? Involved is not the word.

Hi Lee,

Everyone wants more gain. You don't say why and that may negate
wanting gain.

At the frequency you are desiring, performance is very much limited to
line of sight and even 2M handhelds with rubber duckies can work the
Space Shuttle an hundred miles up.

Consider the downside of gain: you are a tourist at the Grand Canyon
and you put a telephoto lens on your camera (high gain). When you get
home and show your pictures to friends, they might ask why you went to
the Grand Canyon but took pictures only of the river bed at the
bottom, or a cactus on the ridge. Too much gain for the intended use
which was to show the ENTIRE canyon in one shot. This would take a
wide-angle lens (very low gain).

I have a wide angle lens (low gain) it`s known as a discone !!!
freq range to 3000megs, supposedly 0db ref dipole that has heard one
or two weak signals just outside its range....now i need a telephoto lens
to make out what it is.......a wideband antenna with gain -- a log
periodic!!!!

With respect Richard, i have a scanning radio receiver that scans up to
2500megs
- that`s a lot of coverage which requires more gain the higher you go....a
discone
just doesn`t cut it gainwise so i need a wideband antenna with more
directional
gain to work alongside the discone...a yagi with one meg bandwidth isn`t
much use
either...imagine how many i would have lying around!!! besides, i know how
to
design those....... :-)


Anyway, simple scaling works. Just research the model of antenna that
gives you the gain characteristics you want, and scale to your band of
interest. The downside here is you may find that you have designed
yourself into a corner because you cannot find the right stock that
supports the dimensions. For a log periodic, this might not matter so
much, and especially for a receiver, but latitude is not generous.


If i knew how to scale or re-engineer an existing design, i wouldn`t be on
this NG
asking how to do it ...

Thanks for the advice Richard ......

73...

Lee......G6ZSG......