# Universal Carbon Yagi Antenna - only 20€!

Jan 10, 2017

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What are good sources for the carbon tubes used for this?

Ebay or Aliexpress etc. :)

Could you maybe increase the element size to 1/4" or 6mm? Getting Welding rod over 3 feet here is a problem but 1/4" is OK. Great design!

Hi,
könntest du mir vielleicht deine genauen Maße mitteilen?
Viele Grüße

Hi there, I'm just planning to make my very first antenna. I think it will be this one so I can receive noaa. However I have a few basic questions as I have never built any kind of antenna.

How much do each rod in the driven element measure? I downloaded the arrl 7db for 7 bucks and it says to calculate the length by using a formula. 475 divided by the frequency you want in mhz. So if it's 475/140mhz it gives me about 3.4ft which is about 40.8". Let's say 41"? So each rod in the driven element should be 20.5" ? I want it for receiving noaa signals, just like you in the video. Do the rods in your antenna's driven element measure 20.5"?

The correct Formula would be the following to compensate for the boom and 1/4 inch of the element protruding the boom.

475/137mhz = 105,5cm
(105cm/2) + boom diameter (1,2cm) + 0,64cm (1/4 inch protruding) = 54,34cm

So each of the feeding elements will be around 54cm.

Thanks! What about the director and reflector size? do they remain the same size as in the pdf? (35" and 40") ?

The PDF states that the reflector is 5% bigger and the director 5% shorter then the driven element.

so when the driven one is 105,5cm: Reflector is 110,75cm and the director is 100,225cm

Oh, I didn't see that. Thanks! No more questions left. I will try to build it soon although I'm having a lot of trouble finding copper welding rods like the ones you used, so I may have to use other kind of material.

They make no sense to anyone and have absolutly nothing to do with the Antenna.

regards,
Manuel

What frequencie did you try to receive?
What did u used? (LimeSDR?)
How far away is that Tower?

wut?

ahhhh no :)

I got a 36db SNR from my backyard, holding the Antenna with my Hands and pointing it at the NOAA sat. The Antenna was about 1,6-1,9m about the Ground, so not that high.

I used a RTL-SDR v3 with FM Trap and LNA4ALL.

regards,
Manuel

But you can find some info about mods on RTL-sdr.com. It seems taht the LimeSDR is not useable under 700mhz because of Hardware issues.

regards,
Manuel

Thanks for the praise.

Sorry, But i will not print or sell any parts for this Antenna. I already had several People ask me that.
Also the shipping would be more expensive then the 3d printed parts itself.

Just search on the Internet for a 3d Printing Service near you :) There are several al over the World. Or look out fo a 3D Printer at a maker space or Library that you can use.

regards,
Manuel

Any chance of getting the design files to scale for other bands?

There is no need for scaling the parts, you can use them for any frequencie you like.

You only have to calculate the lenght of the elelemnts (out of welding rod) and the distance between Driver/Director and Driver/Reflector.
Because they are mounted with clamps, you can adjust the spacing easily.

regards,
Manuel

Actually, I'm interested in 70cm. Since the elements are a lot shorter, I wanted to shorten the wire arms so there's not so much lossy dialectric right on the wires. The boom parts are fine.

Chris

The arms are only 15cm across, so it will not cover that much of the element.
Also the plastic will not effect the gain at all (even when it will be so minor, that it's not noticeable)

Anyway, you can use meshmixer (free) and use plaincuts to cut off the arms as you like :)

regards,

Manuel

Ok, thanks.