Coat hanger - 446 Folded Dipole 3 element Yagi

[Jonny5’s]

Thought I'd share the pictures of my 446mhz Coat Hanger - Folded Dipole 3-element Yagi, as I was very pleased with the results. Tested in my loft, mounted to the end of a PVC pipe, which I was holding, this time the antenna was lower than my usual antenna, which I use for the weekly Monday night PRM net.

I could hear some comms from Ashdown Forrest coming through on Ch14 at full bars, so that was promising, made contact with Nigel CVM, who was at his home QTH, full bars back, I don't normally get him full power from him at that location, so even more promising, then tested on my usual Slim Jim, and power was down a couple of bars, about 13 out of 15 bars with a little crackle.

SWR reading was around 2.3:1, which I managed to get down to 2.1:1. I had fitted a 4:1 Coax balun loop as recommended; however, the loop and feed line were 50ohms, where it was recommended to use 75ohms for the loop and feed line, then into your usual 50ohms run of coax.

I believe from what I have managed to read and find on YouTube, I can improve on the SWR by using the 75ohms coax and the length of the centre lines into the folded dipole, oh, and the correct length of coax balun loop to match the wavelength. 

Anyway, all in all, as crude as the finished product looks, I was pleased with the results. I think I will now build a version out of aluminium tubing with the correct recommended coax ohms and 4:1 coax balun length, and see how that goes.

It was fun to make and see some results from testing.

Design calculator from https://3g-aerial.biz/en/online-calculations/antenna-calculations/dl6wu-yagi-uda-antenna-online-calculator







 

[CT4013]

Well done John, it's great to see the efforts of members.
The million doller question is 'will it help getting over the large mound of chalk to Brighton'?

[Jonny5’s]

Ah who knows, I now have some Aluminium tubing to make a better one, so I'll see how that goes. It might get a couple of extra bars over to you!