As long as the carbon fibre reinforced plastic material is only used for the boom it is ok.
@OK1CDJ Ondra, is this a 10 mm CRP tube or is it 8 mm?
73 de Martin - DF6MH
Hi, it is 8mm carbon tube. There was impossible to get 8 mm or 10mm fiber glass tube. The carbon will be used only for boom.
73 Ondra ok1cdj
I think that will be ok! I’m very interested in your results …
73 Armin
Parts are printed, need make wires and complete the yagi… Here is picture of finished joint…
73 Ondra OK1CDJ
Hi, antenna is finished. Mechanically is all OK.
The best SWR on 153 MHz (on 144MHz nearly 2), the antenna was tested without rubber cords in elements,i will add cords and test it again… Maybe i need to change scaling little bit due to another material… I hope that i will test the antenna this weekend during Czech Activity contest…
I have also some ideas how to make antenna better and for sure i will build next one.
If anyone is interested in 3D printed parts, please let me know.
73 Ondra OK1CDJ
Hi Ondra,.
the mechanical work really looks good, congratulations!
Did you cut the wires before or after you inserted them into your printed joints? Some mm get lost with the wire getting in and out your joint. I cut them afterwards.
The rubber cords will not change much on resonance frequency. Seems that you need to go down by 3 MHz. That means adding around 9 mm per wire end. I would try this before attaching the rubber cords.
I’m not quite sure where the two slight resonances with an VSWR of 3 above the design frequency come from. Can you find this out by fingering around? 
How does you current BALUN look like? Can you make a photo?
73 de Martin - DF6MH
Hi Martin, i cutted wires before, that’s the reason. I will change all elements and make new measurement. I have no balun at the moment, i have SMA connector with short coax soldered directly to dipole. I am waiting for some RG-316 cable…
73 Ondra OK1CDJ
Hi Ondra,
with the wires passing through your joint you more or less loose the mentioned 9 mm per dipole half. Apart from that the resonance looks good! Simulation even predicted this dip you have at upper band edge. I do net see it at my antenna. VSWR is OK with 1.5, my Antenna is also around a 1.5 / 15 dB return loss.
BTW … best PDF ever: Return loss vs. VSWR table 
Maybe the current BALUN also reduces the slight resonances we see in you VSWR plot above the band.
Looking forward to see a picture when you finishes the antenna! And of course everybody wants to know its weight!
73 de Martin - DF6MH
Hi Martin, still waiting for longer coax for 6 el. version 
in think that antenna will be complete this week. Inbetween i made 3 el. yagi DK7ZB (used your formula for scaling down) with 50 cm boom with elements divided to half. Transport length is 30cm. Here are pictures.
Balun:
Collapsed antenna:
SWR:
I made also some minor changes in joint construction. The holes for wire are in 45 deg angle now. There is lower lost of the length of wire for element .
73 Ondra OK1CDJ
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Hi Ondra,
sorry for my late reply. I was in holiday and did not read the email notification about your post.
That’s really cool! It seems that you really like this mechanical principle! Thank you so much for experimenting with it. And also your 3 el. YAGI antenna really looks great! Good idea to also divide the radiating elements for shorter YAGI designs.
Please keep me up to date with your tries.
73 de Martin, DF6MH
Hi Martin, yes like this design very much. I was this weekend in OE (Windberg OE/ST-137) for Alpe Adria Contest. We had bigger antenna for contest but i setup the 6 el. as backup. I tested directivity and all looks ok.
Weight of complete antenna with 5m of coax, tubus and all parts and ropes for mast from trekking poles is 800g.
I forgot to take picture from antenna analyzer, but return loss with 5m cable looks very similar to yours.
73 Ondra OK1CDJ
Hello Ondra,
thanks for the two photos. The antenna looks great and also boom deflection seems to be very low. What do you think, will the crosses also withstand the forces in case of strong winds and low/high temperatures?
I will get in touch with you within the next days. Maybe I can update the document with some photos of your antenna and some hints how to alternatively build it with 3D printed parts. Would you share the mechanical files for your crosses?
vy 73 de Martin - DF6MH
Hi Martin, i am using carbon tube for boom, the deflection is very low. Is not easy to cut carbon tubes, the best way for me is using dremel tool with CUT-OFF wheel.
I thing that i made the joints little bit oversized. They are made from PET-G filament and are very strong.
I put the STL files here: Fiberglass Ultralight YAGI Antenna by ok1cdj - Thingiverse
73 Ondra OK1CDJ
Hi all,
long time no see …
Finally here is the link to the PDF including Ondras printed parts:
http://www.nix-disco.de/misc/DF6MH-fiberglass-yagi-antenna_0p5.pdf
Unfortunately it seems that I cannot edit my first post anymore to edit the link.
I just came back to post a video of an activation including my antenna
Comments are in german language, but anyhow …
73, Martin - DF6MH
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