need to change radiator size
 

I have this parabolic dish that it supposed to be cut for 2.5-2.6 ghz
and would like to make another feed the same shape for 2.45 ghz.
here is a picture, http://pages.ripco.net/~a2k/radiator.jpg
its dimensions are 100x86mm, anyone know the formula for the size
of this type of feed or what its called?

On Mon, 9 Feb 2004 23:56:36 +0000 (UTC), Luddite
wrote:


here is a new picture

http://pages.ripco.net/~a2k/parabolic-feed.jpg

There is only the one element fed by a 3 foot pigtail of 9913.
the plan was to change it to rg-174 or .141 hardline and attach
a USB wifi device to the rear,and add the correct sized feed.
or I might settle for less than its rated 21db gain.

Hi OM,

It is a dual element feed. You have what appear to be two quarterwave
slots, one wavelength apart (probably for better position
tolerancing). What you offer above actually explains nothing. Change
out 9913 to what end? Even RG-58 over that length would serve.
Attach a USB WiFi for what? To transceive?

Why don't you just try it and see what happens? Nothing gonna break
and if it works that's the end of it. If it doesn't work, you have
more problems than a 4% frequency shift.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Mon, 9 Feb 2004 23:56:36 +0000 (UTC), Luddite
wrote:


here is a new picture

http://pages.ripco.net/~a2k/parabolic-feed.jpg

There is only the one element fed by a 3 foot pigtail of 9913.
the plan was to change it to rg-174 or .141 hardline and attach
a USB wifi device to the rear,and add the correct sized feed.
or I might settle for less than its rated 21db gain.

Hi OM,

It is a dual element feed. You have what appear to be two quarterwave
slots, one wavelength apart (probably for better position

could you please explain the dual element part?
I thought they were used for attachment,look closer and you
should see remnants of melted black plastic I sliced off over them.

tolerancing). What you offer above actually explains nothing. Change
out 9913 to what end? Even RG-58 over that length would serve.

in this case its too big for the connectors being used.

Attach a USB WiFi for what? To transceive?
Why don't you just try it and see what happens? Nothing gonna break
and if it works that's the end of it. If it doesn't work, you have
more problems than a 4% frequency shift.






73's
Richard Clark, KB7QHC

On Tue, 10 Feb 2004 09:08:15 +0000 (UTC), Luddite
wrote:

Richard Clark wrote:
On Mon, 9 Feb 2004 23:56:36 +0000 (UTC), Luddite
wrote:


here is a new picture

http://pages.ripco.net/~a2k/parabolic-feed.jpg

There is only the one element fed by a 3 foot pigtail of 9913.
the plan was to change it to rg-174 or .141 hardline and attach
a USB wifi device to the rear,and add the correct sized feed.
or I might settle for less than its rated 21db gain.

Hi OM,

It is a dual element feed. You have what appear to be two quarterwave
slots, one wavelength apart (probably for better position

could you please explain the dual element part?
I thought they were used for attachment,look closer and you
should see remnants of melted black plastic I sliced off over them.

Yes, it did look a bit tacky. It is difficult to judge the design
from a photograph without knowing the composition of the various
components or the scale (you should show a ruler nearby).

Without being able to judge the relative positions and size of these
"plastic" elements, it is difficult to say they are mounting ears or
if they are part of a dielectric lens. Why did you "slice" them at
all?

Another clue that is missing is: What is the orientation of the feed
to the reflector? Here a picture is more meaningful than the one of
the isolated feed.

tolerancing). What you offer above actually explains nothing. Change
out 9913 to what end? Even RG-58 over that length would serve.

in this case its too big for the connectors being used.

Spend $3.98 for an adapter.

Attach a USB WiFi for what? To transceive?
Why don't you just try it and see what happens? Nothing gonna break
and if it works that's the end of it. If it doesn't work, you have
more problems than a 4% frequency shift.

This advice still stands.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

Spend $3.98 for an adapter.

I was right and wrong about the dish,I borrowed a adapter to try
as is and got poor results. so I took the feed apart and found out
what I thought was the radiator (the 3 sided aluminum piece) was just
a passive radiator,no actual connection. there is a dipole inside the
housing whose elements are just over 25mm. assuming its 1/4 wave that
puts it at 3ghz.. the 100mm dimension of the passive part makes sense
in light of this,it needs work but is still useable..