[amsat-bb] Re: Quadrifilar Helices

[kc6uqh]

Robert,
Quadrafilars come in different wave lengths and have different paterns. The 
most common is a 1/2 wave 1/2 turn configuration. If you make two, phase 
them, and point them at a 20 degree angle up from the horizon this will give 
you good coverage and all you need to do is swing them around when the 
satellite is overhead.
If you live as most of us do in a metropoliton area, coverage below 5 
degrees is a dream. Yet 70 % of the time the satellite is less than 20 
degrees of elevation. If the satellite is overhead it is very close to you 
needing no gain, the gain is needed at the horizon. A 1/2T 1/2Wave 
quadrafillar pointed up has full gain at the zenith with a 120 degree beam 
width giving you unneeded performance for only 20 % of an overhead pass.

Art,
KC6UQH
----- Original Message ----- 
From: "Robert Bruninga" <bruninga at usna.edu>
To: "'amsat'" <amsat-bb at amsat.org>
Sent: Friday, November 02, 2007 4:33 PM
Subject: [amsat-bb] Re: Quadrifilar Helices


> On the other hand,
>
> Some folks appreciate it when someone takes the effort to kit-up
> or make a commercial product out of a common design and makes it
> available to others who may not have the time to do their own...
> Nothing wrong with that.
>
>> > Someone replied to me off-list with a commercial
>> > offer for his helix antennas....
>> > and is also using the list to troll for "customers".
>
> As  you said, it was off list. And it sounds like he thought the
> person was intested in a Helix antenna.  He has them.  SO
> nothing wrong with that.  In fact, that is a better approach
> than a message to ALL...
>
>> Good response, Nate.....99.9% of us resent these
>> dorks that use any portion of ham radio for their
>> profit!!
>
> Leave me out of your 99%.  I appreciate when any ham takes the
> effort to commercialize something for the benefit of others.  If
> you don't want to buy it, that's your choice.  But do not condem
> the person for trying to help out others.  It takes a lot of
> effort to make something that other hams can use at a low enough
> cost to make it worthwhile.  I think you should thank them.
> Bob
>
>
>> And I'm going to tell you a story that happened to me
> ~1965...I was
>> stationed at the Naval Air Station, St. Simons Is. GA, and
> discovered
>> plans for a cubical quad...I think it was devised at some high
>
>> altitude in South America to keep corona from burning the ends
> of
>> other designs....
>>
>> There were adequate plans available, probably got mine from
> some ARRL
>> pub, and it was for  10,15 and 20 meters.... The spacing was a
>
>> compromise for the three bands, so I got two four blade car
> fans,
>> bent them, put them on either end of the boom, and got near
> the ideal
>> reflector spacing for all three bands...It worked very well,
> and
>> needed no  matching of any kind.
>>
>> Just about every time I got on the air, this ham in Chicago,
> would
>> join us, and kept asking details about the antenna, so, of
> course, I
>> gave him all the info he requested...
>> I was very pleased that he was that impressed, so I was happy
> he was
>> interested..
>>
>> I got transferred to the Naval Air Station Alameda, CA, and
> about two
>> or three months after I got there I saw an ad in QST for
> aluminum
>> cast spiders with the identical angles that I had bent my 4
> blade car
>> fans!!!!  Advertised by the same ham I had talked to in GA!!
>>
>> So, worth anything or not, all the junk I devise goes on my
>> website...Not to lay claim or anything of the sort...
>>
>> I hope the guy in Chicago was successful, but if he was, I
> never
>> heard anything about it!
>>
>> At least two of us won't promote these jerks!!
>>
>>
>>
>>
>>
>>             73, Dave wb6llo at amsat.org
>>                     Disagree: I learn....
>>
>>                Pulling for P3E...
>>
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>
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