[Moon] [Moon-Net] 3 cm circular polarization

[F5IGK Alain]

Thank you all for the ideas and suggestions about the different feed CP, 
and polarizer of 5.7GHz CT1DMK particularly
I think I'll choose the solution of Luis CT1DMK who told me the 
dimensions of the polarizer for the 42/40mm brass tube I can find in 
France. It was enough to ask !
Thank you for making me enjoy your experience ...
73 f5igk
Le 22/09/2014 11:15, F5IGK Alain a écrit :
> Hi all,
> I wanted to make a cp feed for 5.7ghz (from the description of 
> ct1dmk), but I have not managed to find the tube dimensions "imperial" 
> in France.
> Two solutions: buy abroad, to the United Kingdom for example, or 
> recalculate the dimensions of the PC feed from a tube the size I could 
> find in France.
> That is where I am ....
> And that's why I started in the 10GHz band with vertical linear 
> polaristation !!!
>
> 73's f5igk Alain
>
>
> Le 22/09/2014 02:04, ct1dmk a écrit :
>> Hi folks.
>>
>> There are certainly a lot of possible variations on feed and polarizer
>> designs and I read over time many comments about the construction
>> issues/difficulties along with many comments about the at septum 
>> polarizers.
>>
>> Very little we read about the narrow-section (aka squeeze waveguide) 
>> feeds that
>> are orders of magnitude easier to construct than septum and the OMT
>> that follows can deliver either coax or wg depending on your needs.
>>
>> Don't know the reason but every time the subject of CP feeds on 3cm pops
>> up we read about septum variations and construction efforts.
>> The narrow-section polarizer is extremely easy to construct
>> is just two metal plates soldered inside a round pipe.
>>
>> http://www.qsl.net/ct1dmk/wg_pol01.jpg
>> performance wise same as septum or any other (but less critical to 
>> construction tolerances).
>>
>> most of the plans/dimensions can be found here:
>> http://www.qsl.net/ct1dmk/mw_low.html
>>
>> (before you ask, the OMT section can end in coax/coax, coax/waveguide 
>> and waveguide/waveguide, if the idea is not clear enough look a the 
>> 5.7GHz design
>> that uses the same principle. The article stresses the idea that 
>> Feed, polarizer and OMT
>> are 3 different components that you can choose as required. A feed 
>> for the proper illumination of your dish(not necessarily what we 
>> present), the polarizer and the OMT with the configuration required).
>>
>> Me and Willy (LX1DB) we have published Dubus articles with those feeds
>> nearly 10 years ago... not fashionable at the time... and not yet 
>> fashionable today
>> I'm afraid :-(
>>
>> I know there are a few hams that have constructed several and have 
>> photos
>> in their web pages I just don't remember who/where. If you don't mind 
>> to chime in and let us all know tks.
>>
>> 73's
>> Luis Cupido
>> ct1dmk
>>
>> p.s. Interesting enough this technique makes 23cm 13cm and 9cm feeds 
>> quite
>> simpler to build (compared to septum)... We must ask Willy (LX1DB) to 
>> show his photos, also a PA station I can't recall that have made some 
>> fantastic constructions as well.
>> I have built 10GHz and 8.4GHz as you see on my pages but have 
>> designed/simulated
>> nearly for all bands from requests of hams (lost count), so I presume 
>> some neat constructions must exist out there.
>>
>>
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>
>
>
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