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Old Jan 24, 2011, 09:19 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
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Originally Posted by Hugeone View Post
Great!!!

Why 12 turns max?


-Hugo
Efficiency drops considerably after 12 turns. You can go as many as you want, but the efficiency drops greatly and the gain increases slowly.

-Alex
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Old Jan 24, 2011, 09:21 PM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Originally Posted by sawman View Post
Thanks for posting this Alex. And thanks for being open about the beliefs that this country was founded upon. Too bad folks have forgotten that aspect. "There is no other name by which we must be saved."

One question; How does the beamwidth of this antenna compare to the Bi-quad ?
It depends on the number of turns. The beam is similar to the BiQuad. More turns = narrower beam.

I hear you on the beliefs. I believe every bill in my wallet states "In God We Trust".

-Alex
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Old Jan 24, 2011, 09:23 PM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Originally Posted by flyboy321 View Post
And, he's done it again

I'll be building your inverted vee this weekend, and then possibly this in a few weeks!

How would this compare to say, a rubber ducky antenna? -Tyler
There is no comparison. It is night and day difference.

-Alex
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Old Jan 24, 2011, 10:19 PM
I AP'd myself again......
aviatordave's Avatar
Yawn....Iowa
Joined Mar 2005
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Originally Posted by IBCrazy View Post
Before I write this, I need to give thanks to a few people for their help. It’s people like these that make this hobby great:

A special thanks to Dave Albert (Dalbert02) for taking the time to do extensive testing of these antennas. Without him, this would not have been possible.

I also want to thank:
Old Man Mike – For his great explanations on CP systems
Nigel (devonboy) – For introducing the skew planar wheel and its feasibility which make CP a reality for FPV
Blupp – For his ideas, support, and independent research
Steven Katz (WB2WIK) – It was his idea for the RG62 impedance match.
Juan Nurmela (OH5NXO) – For recognizing a better microstrip match.

-Alex

I like reading your tutorials. Although you forgot to thank the Big guy.
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Old Jan 25, 2011, 06:01 AM
RC = FUN
Fort Wayne, Indiana
Joined Aug 2008
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Originally Posted by IBCrazy View Post
Q: How will this work with the Turnstile, Caltrop, and Bluppnik antennas?
A: Better than the Vee and much better than a whip, but exactly how much, I don’t know.

How come this doesn't work as good with the vee?
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Old Jan 25, 2011, 06:09 AM
Registered User
France
Joined May 2006
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What are the benefit of this antenna , what flying style is it for ?
Do you have any beamwidth data on it; angle ?
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Old Jan 25, 2011, 06:36 AM
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Originally Posted by flyboy321 View Post
How come this doesn't work as good with the vee?
This is a circularly polarized antenna. it works best with other circularly polarized antennas. Linearly polarized antennas such as the Vee will experience a 3db polarization loss.

The bluppnik and turnstile are dual polarized. The caltrop is eliptically polarized. These all will match the helical fairly well, but not perfectly. These antennas were designed to work with both linear and circularly polarized antennas.

The best match to the helical is the Skew-planar wheel.

-Alex
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Old Jan 25, 2011, 06:39 AM
Engineer for Christ
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Quote:
Originally Posted by vulpina View Post
What are the benefit of this antenna , what flying style is it for ?
Do you have any beamwidth data on it; angle ?
The helical is for all styles of flying, especially stunt flying as there is no signal loss in a bank or loop.

Beam witdth is inversely proportional to the gain and number of turns:

3 turns - 75 degrees
6 turns - 55 degrees
12 turns - 40 degrees

-Alex
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Old Jan 25, 2011, 07:39 AM
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I write this and all of my tutorials in the name of Jesus Christ. It is with His heart, and God’s blessing that I freely give this away to the FPV community. Without them, this tutorial and others that I have written would never have existed.
Thanks a lot again Alex, theres no price for what you´ve been doing for us sharing all your knoledge.

Yesterday I made my first fpv flight using your "v" antena design and it was perfect.

Once again, thanks a lot sharing with us
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Old Jan 25, 2011, 09:01 AM
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United States, NC, Charlotte
Joined May 2009
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Currently in your tutorials is the skew-planar the only homebrew that is suitable to match this? I am interested in CP but I have not gone on with it mostly due to the problem of a durable TX antenna. To me the SP looks like something that I would destroy very rapidy, so I am hoping you have some alternatives in the works?
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Old Jan 25, 2011, 09:28 AM
K0RSQ
Saint Louis, Missouri, US
Joined Sep 2010
139 Posts
Wow Alex, great work! I hate to be the whiny guy, but could you post more/better pics of the #3 & #4 impedance matches (microstrip & conductor), especially how they are installed on the antenna? The Hecker transformer (I never knew it was called that) has been the only impedance match I've ever seen on a home-made helical before, so I'm really curious about these alternate methods. What exactly are you referring to as "height" in the calculations?

What do you think is the best material to use for the support brace? I have access to CNC-cut G10/FR4, but it looks like it has a significant dielectric constant and even adjusted for it there is ~>3dBi loss in gain. I'd like to use something CNC-cut, as the notches could be accurate to within a few hundredths of an inch. Maybe hobby plywood? Do you happen to know if adding a water-resistant coating like Thompson's WaterSeal will change the dielectric properties? Google had no love for me on that one.
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Old Jan 25, 2011, 10:35 AM
Engineer for Christ
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Amherst, VA
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Quote:
Originally Posted by cmccracken View Post
Wow Alex, great work! I hate to be the whiny guy, but could you post more/better pics of the #3 & #4 impedance matches (microstrip & conductor), especially how they are installed on the antenna? The Hecker transformer (I never knew it was called that) has been the only impedance match I've ever seen on a home-made helical before, so I'm really curious about these alternate methods. What exactly are you referring to as "height" in the calculations?

What do you think is the best material to use for the support brace? I have access to CNC-cut G10/FR4, but it looks like it has a significant dielectric constant and even adjusted for it there is ~>3dBi loss in gain. I'd like to use something CNC-cut, as the notches could be accurate to within a few hundredths of an inch. Maybe hobby plywood? Do you happen to know if adding a water-resistant coating like Thompson's WaterSeal will change the dielectric properties? Google had no love for me on that one.
You are way overthinking this. The Helical is wideband. If you make the cross very thin the dielectric properties will not affect the antenna performance much.

As for the photos, I will post more after I build some more antennas. The camera memory card went bad on me when I tried to upload the photos. All of the antennas in the tutorial are on their way to Florida for testing. I plan on making a few more in the coming days for some beta testing.

-Alex
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Old Jan 25, 2011, 10:40 AM
Engineer for Christ
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Quote:
Originally Posted by Derek_S View Post
Currently in your tutorials is the skew-planar the only homebrew that is suitable to match this? I am interested in CP but I have not gone on with it mostly due to the problem of a durable TX antenna. To me the SP looks like something that I would destroy very rapidy, so I am hoping you have some alternatives in the works?
Currently, yes. The bluppnik, caltrop, and turnstile have not been perfectd yet. You can fly my Vee with a helical and never lose signal in a bank. However you lose 3db from polarization loss.

I fly a 1.3GHz skew planar wheel made from .030" mig welding wire. Despite numerous crashes, it still works great. I haven't broken it yet.

-Alex
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Old Jan 25, 2011, 10:52 AM
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Right, on my 2.4 Vtx I fly CP on the GS and omni on the plane. However I still lose some signal in a bank, and I have wondered if the Patch sold to me from NG as CP is actually CP at all.
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Old Jan 25, 2011, 12:54 PM
It just keeps getting better!
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Eureka, CA
Joined Oct 2002
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Another great tutorial.
Thanks for all your thought efforts.
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