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Old May 23, 2012, 06:32 PM
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idletime's Avatar
Canada, ON, Toronto
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Originally Posted by Slaphappysamy View Post

...... CNC using sw/solidcam....

https://vimeo.com/42712761
That's why the rest of us can't have nice things!!
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Old May 24, 2012, 09:32 PM
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United States, TX
Joined Oct 2010
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That's why the rest of us can't have nice things!!
lol. I snuck out in the shop tonight after dinner and got the acrylic machining and assembly finished. I liked white better than blue so I went with it for the base caps. Should make Sat's work a breeze now.
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Old May 25, 2012, 11:55 AM
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Amherst, VA
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Originally Posted by wannabe View Post
Dosent the wave trap have to be paralell with the reflector?
No. That's a microstrip match. I found the wavetrap to be easier and more precise. The wavetrap is just a rectangular piece of metal. The microstrip is curved.

-Alex
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Old May 25, 2012, 03:51 PM
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United States, CA, Vacaville
Joined Oct 2003
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Originally Posted by IBCrazy View Post
No. That's a microstrip match. I found the wavetrap to be easier and more precise. The wavetrap is just a rectangular piece of metal. The microstrip is curved.

-Alex
Golly! I went to great legnths to make thing flat!
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Old May 29, 2012, 05:41 AM
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SINGAPORE
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Originally Posted by ricknoon View Post
Tonight my wife and I tested out my first attempt at a helical antenna. I compared the helical with my cloverleaf antenna (which is proven out to 2km on my plane) by driving our Saturn line of sight and marking where the signal dropped off.

Unfortunately both antennas dropped out at around 1.2km, but that exact spot was under an intersection of two power lines.

I'm excited to see what this helical can do with my plane in the air. Can you see any areas of improvement on this helical?
Have your wife point your helical in the direction of your plane as you are flying in FPV, and you will be amazed with how crisp the video is. It beats the most well-tuned omni CP antenna.
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Old May 30, 2012, 10:32 PM
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United States, CA, Arcata
Joined Oct 2011
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Ok I have been pushing my limits, and got 3km out of my bluebeam set today, now I am thinking it is time for a helical! I was looking at RMRC's selection, and I noticed there is a 3 turn (which stated a 75 degree beam I believe), and a 5 turn which did not state the beam width, so my question is what is a 5 turn helicals beam width?

Also what ranges could one expect on 1280 with 700mw vTX using SPW/Cloverleaf (would there be an improvement putting the SPW on the plane over the cloverleaf?) using both a 3 turn and 5 turn helical?
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Old May 31, 2012, 12:19 AM
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Australia, QLD, Brisbane
Joined Feb 2011
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Originally Posted by NorCalMatCat View Post
Ok I have been pushing my limits, and got 3km out of my bluebeam set today, now I am thinking it is time for a helical! I was looking at RMRC's selection, and I noticed there is a 3 turn (which stated a 75 degree beam I believe), and a 5 turn which did not state the beam width, so my question is what is a 5 turn helicals beam width?

Also what ranges could one expect on 1280 with 700mw vTX using SPW/Cloverleaf (would there be an improvement putting the SPW on the plane over the cloverleaf?) using both a 3 turn and 5 turn helical?
Not sure on range but a 5 turn has a beamwidth of about 45*
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Old May 31, 2012, 12:57 AM
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Australia, QLD, Brisbane
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About to try my hand at making a helix and i wanted to clarify a few details. I used jcoppens calculator to determine most of the measurements but am unsure on a few (marked with ????)

Most of the details that i have listed seem consistent with others making 5.8Ghz (hard to find details on 5.8 specs)

Design frequency 5800MHz
5 turns
Internal diameter 17.5mm
Wire diameter 1mm
Coil centres 12.9mm
Reflector 32mm diameter minimum (Will make mine 35mm)
Wave Trap size 6.5mmx3.2mm
Wave Trap spacing from feed point 3.2mm ???
Seperation at feed point .4mm ???

I have also seen mention of maintaining the feed point seperation gap for the first quarter turn but this wasn't mentioned in any of Alex's initial posts so just wanting to clarify if it is necessary.

Thanks
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Old May 31, 2012, 02:29 AM
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Melbourne, Australia
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Quote:
Originally Posted by nogas View Post
About to try my hand at making a helix and i wanted to clarify a few details. I used jcoppens calculator to determine most of the measurements but am unsure on a few (marked with ????)

Most of the details that i have listed seem consistent with others making 5.8Ghz (hard to find details on 5.8 specs)

Design frequency 5800MHz
5 turns
Internal diameter 17.5mm
Wire diameter 1mm
Coil centres 12.9mm
Reflector 32mm diameter minimum (Will make mine 35mm)
Wave Trap size 6.5mmx3.2mm
Wave Trap spacing from feed point 3.2mm ???
Seperation at feed point .4mm ???

I have also seen mention of maintaining the feed point seperation gap for the first quarter turn but this wasn't mentioned in any of Alex's initial posts so just wanting to clarify if it is necessary.

Thanks
I'm looking at building a 5.8 too but my measurements (derived from the first few posts) are:

The support brace

Cross width = 15.8mm
Coil spacing = 12.7mm
Length will just be a multiple of the spacing, so x5

I was led to believe that bigger is better for the helical wire so I will use 1/8" tubing

Reflector = 51.4mm (11732/5800 x 25.4)

Wave trap worked out the same as yours. 6.4x3.2

I'm assuming the Cross Width difference is because of PVC use but Reflector measurements should be the same?
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Old May 31, 2012, 03:27 AM
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NRW, Germany
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Quote:
Originally Posted by nrg2go View Post
I'm looking at building a 5.8 too but my measurements (derived from the first few posts) are:

The support brace

Cross width = 15.8mm
Coil spacing = 12.7mm
Length will just be a multiple of the spacing, so x5

I was led to believe that bigger is better for the helical wire so I will use 1/8" tubing

Reflector = 51.4mm (11732/5800 x 25.4)

Wave trap worked out the same as yours. 6.4x3.2

I'm assuming the Cross Width difference is because of PVC use but Reflector measurements should be the same?
Although i got no clue about building those antennas, i often heard that a thicker wire will not be "better" but more broadband. So you might cover 5600-5900 MHz with that thick wire antenna, but the efficiency will be worse than a fine tuned thin wire antenna which is optimized for ~5800MHz.
More broadband = receive more reflections.

So maybe a thick wire is not really a great idea. Can IBCrazy or Markus confirm that, or am i getting this wrong?
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Old May 31, 2012, 03:44 AM
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Switzerland, LU, Buchrain
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Quote:
Originally Posted by BKMorpheus View Post
Although i got no clue about building those antennas, i often heard that a thicker wire will not be "better" but more broadband. So you might cover 5600-5900 MHz with that thick wire antenna, but the efficiency will be worse than a fine tuned thin wire antenna which is optimized for ~5800MHz.
More broadband = receive more reflections.

So maybe a thick wire is not really a great idea. Can IBCrazy or Markus confirm that, or am i getting this wrong?
The problem boils down to wether someone does have propper measuring equiepement and know how to fine tune an antenna or not.

If not, the thick wire aproach, alas going wideband is probably right as you then at least somehow cover the frequency you operate on. If you then want to improve things, one should either get equipement and build up the know how to make it right or - much much simpler and cheaper - buy an antenna made by a professional.

HTH

Markus
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Old May 31, 2012, 03:52 AM
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Melbourne, Australia
Joined Apr 2009
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Quote:
Originally Posted by BKMorpheus View Post
Although i got no clue about building those antennas, i often heard that a thicker wire will not be "better" but more broadband. So you might cover 5600-5900 MHz with that thick wire antenna, but the efficiency will be worse than a fine tuned thin wire antenna which is optimized for ~5800MHz.
More broadband = receive more reflections.

So maybe a thick wire is not really a great idea. Can IBCrazy or Markus confirm that, or am i getting this wrong?
I got no clue either but post #3 clearly says bigger is better. It even goes so far as to say copper tubing is supreme. Go figure.
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Old May 31, 2012, 04:20 AM
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Australia, QLD, Brisbane
Joined Feb 2011
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You may find post 3 is talking about building for 1280mhz. Different kettle of fish.

Hey Markus, can you confirm if my measurements are correct?
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Old May 31, 2012, 12:33 PM
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United States, MA, Sturbridge
Joined Jun 2008
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Wave trap question. Does the wave trap have to be placed horizontally, or can it be placed vertically?

The reason I ask is that I am making a helical that breaks down into to parts (ground panel separates from tube) for easy transport in a case. The wave trap is in the way positioned horizontally as it sticks out to the side and is susceptible to damage.
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Old May 31, 2012, 03:52 PM
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Switzerland, LU, Buchrain
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Quote:
Originally Posted by slowjett View Post
Wave trap question. Does the wave trap have to be placed horizontally, or can it be placed vertically?

The reason I ask is that I am making a helical that breaks down into to parts (ground panel separates from tube) for easy transport in a case. The wave trap is in the way positioned horizontally as it sticks out to the side and is susceptible to damage.
Choose the hecker transformer aproach then. That should do for your application.

Markus
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