[Moon-net] Fw: Feed choice

[peter blair]

The IEEE designers
> empirically determined their dimensions, lacking the computer capabilities
> back in when their study was done.  Therefore, there is no formulas or
> theoretical design to work from.
  Really?As a practicing engineer at the time the original Tsandoulous paper 
was published in the microwave journal I'm intrigued as to where you got 
that notion from!
73 Peter
----- Original Message ----- 
From: "Edward R. Cole" <al7eb at acsalaska.net>
To: "DEHAYS Dominique" <dominique.dehays at enac.fr>; 
<moon-net at list-serv.davidv.net>
Sent: Thursday, February 08, 2007 8:20 AM
Subject: Re: [Moon-net] Fw: Feed choice


> At 08:54 AM 2/8/2007 +0100, DEHAYS Dominique wrote:
>>
>>Hi all ,
>>
>>if my informations are acurate ,  there will be a "SUPER VE4MA" feed with
>>Septum polarizer described in DUBUS for 23 and 13cm  ( maybe in the next
>>issue? ). So you will get good information.
>>I had the opportunity to read it in avance ( tnx to the author). I just
>>wonder one thing : there is some calculations done in the article , one of
>>them is feed horn diameter. I saw that this diameter is different for
>>linear and for circular polarisation , I wonder why? Anybody knows?
>>
>>73's Dom/F6DRO/JN03TJ
>>
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>
> Dom,
>
> I have read most of the articles written by Zdenek OK1DFC and Paul W1GHZ
> and the original IEEE paper from which the current design is derived.
> Simply put, the septum polarizer operates near the lower cutoff frequency
> of the waveguide.  For a linear polarzed feed one might want to operate a
> little farther above cutoff to reduce losses.  Just a guess!  The ham
> septum designs are scaled from the original design.  The IEEE designers
> empirically determined their dimensions, lacking the computer capabilities
> back in when their study was done.  Therefore, there is no formulas or
> theoretical design to work from.
> 73's,
> Ed - KL7UW
> =========================================
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> 144-EME: FT-847, mgf-1801, 4xM2-xpol-20, 185w (QRV)
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