Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters, which have been excellent thus far.
Thanks
John KB2HSH
----- Original Message ----- From: "John Marranca, Jr" [email protected] To: [email protected] Sent: Thursday, November 01, 2007 2:46 PM Subject: [amsat-bb] Quadrifilar Helices
Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters, which have been excellent thus far.
Thanks
John KB2HSH
Hi John, KB2HSH
Radio Rivista 10/1998 pages 23 to 30 carries out an article specific for a Quadrifilar Helix Antenna designed for 70 cm. The article is in italian but you can follow the drawings and pics and since it is difficult for you to find Radio Rivista I have sent to you a zipped file of the article in a separate email wich is 2.71 MB long.
AMSAT JOURNAL May/June 2004 pages 6 to 10 carries out an article specific for a QFA at 2400 MHz but there are conversion factors in it to scale the antenna for 70 cm In addition there are general informations on how to wound both coils to get RHCP or LHCP as well to connect the loops to get backfire or endfire radiation.
Best 73" de
i8CVS Domenico
Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters...
Not to belabor the point, and just to clarify... but the "ideal" omni antenna can never be better than - 2 dB over a dipole. In other words, "worse" than a dipole by 2 dB. So be careful about trying to get "omni" improvement over what might already be all there is.
A cross polarized antenna like the quadrifilar can be as much as 5 dB worse than a dipole, while still correctly making the claim as being the BEST hemispherical omni antenna. Which it is... If... It all depends on what "best" means. No antenna can give gain anywhere, without giving up gain somewhere else. The ideal omni is equally poor in all directions.
The "best" antenna with equal gain in all directions and horizon-to-horizon cannot possibly have enough gain at the horizon to pull in some of our weak AMSATS, while it will have excess gain overhead where it is not needed.
A possible shaped gain antenna might try to add more of the gain at the horizon at the expense of less gain overhead will result in more or less weak signals everywhere. But on the other hand, satellites spend 70% of their time below 22 degrees. If you can see down that far, then go for it. But the satellites are 10 dB farther away down there and most simply will not be decodable on any OMNI that low.
A simple antenna that concentrates its gain above about 15 degrees is simply a 1/4 wave whip over a ground plane. Yes it has a null directly overhead, but the satellite is in that cone above 60 degrees less than 2% of all times in view. So it is better to give up that gain where it is not used, and let more of that gain contribute to the 5 dBi or so gain that the 1/4 wave whip gives between 15 and 60 where the satellite will come in nice and strong.
If you cannot see below 25 degrees from your location, then you can get 3 dB more gain and get great signals, but only above 25 degrees. Use a 3/4 wave whip which will give almost 8 dBi gain between the 25 to 70 degree range, and since the satellite is 6 to 10 dB closer in this area, then you get almost 14 to 18 dB better performance above about 25 deg than the BEST theoretical omni (isotropic) antenna that is trying to pull in the weak ones at the horizon and everywhere else.
There is no holy grail. Quadrifilar's and Eggbeaters are ideal and the BEST hemispherical antennas in all directions and polarizations... They are perfect for good strong satellite downlinks. But only if there is enough signal there in the first place to be above the noise floor of your preamp. In most AMSAT's, on the horizon, that signal simply is not strong enough. SO in my opinion, it is a waste to have the gain on the horizon at the expense of gain higher up where you can use it for better signals...
Just a data point. See the discussion at the bottom 1/3rd of my ASTARS page:
http://www.ew.usna.edu/~bruninga/astars.html
Bob, WB4APR
Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters, which have been excellent thus far.
Hi John, I have measurements for 70, 2M satellite and 2M repeater freqs at:
http://home.san.rr.com/doguimont/uploads/
It is called Quadfil1.zip
They are a noticeable improvement over and eggbeater....
Be glad to help with any questions you may have....
73, Dave [email protected] Disagree: I learn....
Pulling for P3E...
QST ran an article a few years back
nick ----- Original Message ----- From: "John Marranca, Jr" [email protected] To: [email protected] Sent: Thursday, November 01, 2007 8:46 AM Subject: [amsat-bb] Quadrifilar Helices
Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters, which have been excellent thus far.
Thanks
John KB2HSH
-- _______________________________
John Marranca, Jr PBX Technician/Shop Steward CWA Local 1122 BN Systems, Inc Orchard Park, NY (716)972-2006 _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
The Satellite Experimenters Handbook by Martin Davidoff K2UBC (1990 Pages 8-15 & 16) and it's successor The Radio Amateur's Satellite Handbook (1998 pages 10-13 to 10-15) both have details of this antenna, its use and its construction. I recommend this book to all satellite experimenters and users, it may be nearly 10 years old but the principles and information contained therein have not changed.
Robin Haighton VE3FRH Immediate Past President AMSAT
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Nick Pugh Sent: Friday, November 02, 2007 7:35 AM To: John Marranca, Jr; [email protected] Subject: [amsat-bb] Re: Quadrifilar Helices
QST ran an article a few years back
nick ----- Original Message ----- From: "John Marranca, Jr" [email protected] To: [email protected] Sent: Thursday, November 01, 2007 8:46 AM Subject: [amsat-bb] Quadrifilar Helices
Does anyone know of a website or of construction plans for an 70 cm Quadrifilar Helix antenna? I have heard that they work quite well for an omni-directional LEO antenna. I am looking for an improvement over my Eggbeaters, which have been excellent thus far.
Thanks
John KB2HSH
-- _______________________________
John Marranca, Jr PBX Technician/Shop Steward CWA Local 1122 BN Systems, Inc Orchard Park, NY (716)972-2006 _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
The Satellite Experimenters Handbook by Martin Davidoff K2UBC (1990 Pages 8-15 & 16) and it's successor The Radio Amateur's Satellite Handbook (1998 pages 10-13 to 10-15) both have details of this antenna, its use and its construction. I recommend this book to all satellite experimenters and users, it may be nearly 10 years old but the principles and information contained therein have not changed.
Robin Haighton VE3FRH Immediate Past President AMSAT
That's exactly where I started, Robin, on page 6-20 of the original edition. But Maxwell's measurement produced a horrible VSWR.....I saw Marty later on at a convention, and I believe he said the same thing happened to him...
It took me 4 iterations to get the antenna flat with no matching device...I of course did it at 435. But those dimensions translated very successfully to 2M satellite, 2M repeaters, and believe it or not to 2.4 gigs....In front of a dish, of course!!!
I had seen other pictures of the antenna, and was very interested prior to Marty's excellent depiction of the construction details...
I used a combination of 435 and 2M versions fixed at about 45°, and rotated in AZ only and worked very well with strong signal birds...
Quadfilxxxxxxxxx has the dimensions for the 3, but the 2.4 gig computation is left as an exercise for those interested.
http://home.san.rr.com/doguimont/uploads/
Nice to hear from you, Robin....R U active on any of the birds??
73, Dave [email protected] Disagree: I learn....
Pulling for P3E...
Someone replied to me off-list (thinking I was the person who wanted information on the helix antennas after my Red Green style "duct tape" comment) with a commercial offer for his helix antennas.
Fairly unimpressive, since whoever it was both picked the wrong person to reply to, and is also using the list to troll for "customers".
Not going to bother to say who it was -- but I'm not impressed. I just deleted it to save myself from replying and saying something obnoxious to the person directly.
Nate WY0X
Someone replied to me off-list (thinking I was the person who wanted information on the helix antennas after my Red Green style "duct tape" comment) with a commercial offer for his helix antennas.
Fairly unimpressive, since whoever it was both picked the wrong person to reply to, and is also using the list to troll for "customers".
Not going to bother to say who it was -- but I'm not impressed. I just deleted it to save myself from replying and saying something obnoxious to the person directly.
Good response, Nate.....99.9% of us resent these dorks that use any portion of ham radio for their profit!!
Innovations, and helpful tips should be a part of our hobby. If one has something commercially viable, go ahead and advertise commercially, patent it, or whatever, but not on here...
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 [email protected] Disagree: I learn....
Pulling for P3E...
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 [email protected] Disagree: I learn.... Pulling for P3E...
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
I suspect that the 99% would more accurately describe those who appreciate what skill and effort others may have to offer the Ham community, even when they ask for monetary compensation. I do resent that people would use this list for their egregious ad hominem attacks.
73 George K6ITE
Robert Bruninga wrote:
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 [email protected] Disagree: I learn.... Pulling for P3E...
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
On Nov 2, 2007, at 5:33 PM, Robert Bruninga wrote:
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...
Ahh, I didn't want this to blow out of proportion on the list, I was most annoyed that the person made the offer without reading the list messages carefully enough to realize I wasn't interested in helix antennas in the first place.
I do respectfully disagree though, Bob. I'm not here to be advertised to -- got plenty of that on the Internet already or I can buy a QST which is about what, 50% ads now? Plenty of that to go around already.
If I wanted a helix antenna and he e-mailed me after carefully reading and following this list (being engaged enough to actually know what's going on in the threads), I would agree with you. There's lots of hams out there squeaking out a living off of their ham products, or just paying for their hobby... that's one thing... A plugged-in "community" member helping out... just like you said.
But getting an advertisement from someone who isn't paying attention at all, that's not appropriate. That's just an alternate way to spam. I would actually rather they did send it to the list in that case, if a particular list's rules allowed advertising.
That's my opinion, anyway.
And I wasn't meaning to make any "ad hominem attacks" -- even though that comment in and of itself was a veiled one, aimed at me, I think. (Ironic, isn't it?)
Ultimately none of the above matters at all, nor do I really care.
I was just trying to warn others that someone was trolling the list for customers, while sending it in public and not getting ankle deep in a private e-mail argument with the person that did it. Trying to keep it non-personal while also warning others that someone was trolling the list for customers.
What folks do with that information, is utterly up to them now. I don't care. I wasn't intending it as a topic of discussion, really.
We'll all have our own tolerance levels for advertising and commercial type ham radio ventures, I'm sure... which would change depending on whether or not we WANTED the item for sale, too... unless we're awfully driven by principal. :-)
Wasn't worth me even mentioning it. Sorry I did.
-- Nate Duehr, WY0X [email protected]
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" [email protected] To: "'amsat'" [email protected] 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 [email protected] Disagree: I learn.... Pulling for P3E...
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (9)
-
Dave Guimont -
George Maurer -
i8cvs -
John Marranca, Jr -
kc6uqh -
Nate Duehr -
Nick Pugh -
R.Haighton -
Robert Bruninga