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@usna.edu To: "'amsat'" amsat-bb@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@amsat.org Disagree: I learn.... Pulling for P3E...
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