Customizable Helix (Helical) Antenna Frame and Winding Template

by stylesuxx Sep 3, 2017
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Great project!
Do you know any resources about how to calculate dimensions for a specific frequency? I would like to make antennas for 433MHz and 866MHz.

Ohh, didn't saw that one ^^'
Thank you very much :-)

Comments deleted.

I also have a question for the wave trap. I already made the antenna and it seems to be working awesome. What is the purpose of the wave trap and should i install one on the antenna? How will I know if adding it makes it worse or better without flying? thanks!!! Awesome Design!!!

Unfortunately the wave trap is a bit mysterious to me too. As far as I understand it is an impedance match, there are different ways of doing this and the wave trap is one way. I would strongly recommend to go through this thread on rcgroups if you want to learn more => https://www.rcgroups.com/forums/showthread.php?1377791-Circularly-Polarized-Helical-antenna-7-5-13-dbi-New-Wave-Trap-match%21

If you want to measure it, you can do so by using a SWR meter, check out ibcrazy's video about that topic => https://www.youtube.com/watch?v=G94JY-04wok

The thing files you have for direct download are LHCP but the naming indicates RCHP.

Yes, thank you. I adjusted it in the SCAD file, but did not update the STL's did that now. Thank you for bringing this to my attention.

Could it be that the polarization direction is inverted in the SCAD source? I printed an RHCP template, but the spiral came out as an LHCP one.

Yes, you are absolutely right - as mentioned in the comment to your make, I now fixed this and uploaded a new SCAD file - thank you.

Thanks to you for the design! It works wonderfully.

Hey Chris,

I've got a question about the wavetrap. I noticed that when your design is scaled down to 2.4 GHz, the 1/4 turn where the wavetrap is appears to be at a constant height and the spiral starts going in the z axis the next 1/4 turn. Is that the design intent? I make mine to launch right into an upward slope and it sweeps pretty well on a vna. I could build up another one that follows your design exactly, but figured it couldn't hurt to ask.

Thanks for this awesome contribution!


Thanks for your question regarding the first 1/4 turn. I had the sam issue and unfortunately bad VSWR of 2.36 when i build it like in the manual. (first 1/4 in the hight of 2.5mm with wavetrap there). After that i modified it like in IBCrazys tutorial with wave trap in first upgoing 1/4 turn.Then my VSWR was 1.36. After some mm trimming work i could reach VSWR of 1.06 @ 2370 MHz.

Hey Paul,
to be honest, my information and knowledge about the wavetrap is very limited. I need to get a directional coupler so I can do measurements and see what works best. All the information I have is from IBCrazy from the rcGroups thread I link in the description.

From what I understand the first quarter turn should be same distance from the reflector, with the wavetrap being in the center of the first quarter turn.

I am sorry I can not really help you out here, the wavetrap is a bit magical to me without being able to measure the antenna and compare with other variants,...

It worked well for me, so I felt confident releasing it to the public.

Thank you for posting your make and for your feedback. Are you happy with the performance of your build?
I am not entirely sure what you mean by "...it sweeps pretty well on a vna", could you elaborate?

Thanks so much for taking time and giving feedback, very much appreciated.

Ok, I'll build one like that and take a set of measurements for comparison :)

Oh sorry about that, sure a VNA is a Vector Network Analyzer. It can measure the return loss of an antenna (among other things). If you take a peek here: https://www.thingiverse.com/make:384925 I included the sweeps from the vna. The swr was below 1.2 for most of the 2.4 GHz band.

Thanks again for sharing this design!

Customizable Helix (Helical) Antenna Frame and Winding Template
by laup_x

Ahh, yes - totally missed the sweeps in your make.
If you could make comparisons, that would be totally awesome, thank you!
Could you tell me more about the test setup with the VNA? Being able to sweep across the whole band sounds pretty comfortable.

My intention was to build a SWR meter as described here by IBCrazy => https://vimeo.com/33568135
Your method is definitely more visual - seems I should save up for a VNA :-)