Re: WG16


R Hopkins
 

Hi Brian
I used a "?" feed on my 3cms equipment (mostly ATV) for a number of years using 22mm copper pipe.
The signal always seem to emerge from the end of it in the same polarisation as it went in but I
think that was probably just luck. Although I could never seem to be able to null out GB3XG by
rotating the LNB. Is it possible for the signal to have become circularly polarised? Or is that a
daft idea?

There's a picture of it on my QRZ.com entry. I think that day GW4DGU was using one of his 100uW
transmitters and I received quite a good signal from him over about 45 mile path.

Roger GW4NOS

On Thu, 4 Aug 2016 20:13:14 +0100, you wrote:

In message <nnsadc+psvv3f@YahooGroups.com>, "g4uvz@yahoo.co.uk
[ukmicrowaves]" <ukmicrowaves@yahoogroups.com> writes
Mm


---In ukmicrowaves@yahoogroups.com, <pa0jme@...> wrote :

Adrian, I can recall the use of copper water-pipe, if you like I will
try and search for the article(s) I think it was in UKW-berichte years
ago.

73es Rien PA0JME


Many thanks for the idea! The challenge will be, getting a transition
from WG16 to waterpipe....transition to SMA is well documented.


Adrian
I made a transition from water pipe to WG16 by forcing the end into a
WG16 flange and gently tapping out a taper from rectangular to circular
over a few wavelengths with some matching screws. I used it to
interface to a circular scalar feed , so it was quite short. I actually
found the end of the water pipe did just as good a job as the scalar
feed.

I also had a friend who worked for the water board make me a ? feed
out of water pipe. The problem was that the polarisation rotated in an
uncontrolled manner. I was going to try to roll the pipe slightly to
make an ellipitical guide , but ended up using the scalar feed with
flexible waveguide.

Brian GM4DIJ

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