Novel Yagi design ? Not sure, expert opinion required

Hi all

I’ve recently been experimenting with Yagis for 2M and “discovered” something that has probably been discovered before (!), but I can’t find anything in the literature.

One of the issues with a Yagi is matching to 50 ohms, as the driven element impedance is too low if you just have a dipole. There are various solutions ranging from a folded driven element, to coax baluns, delta or gamma match. These all tend to be a bit unwieldy for a portable setup, and may be difficult to tune especially with a home built one.

In MMANA, I was playing around with a design based on a DL6WU short boom antenna, with either 4 or 6 elements. As expected, the feed point impedance came in around 20 ohms.

I then experimented with MMANA’s optimization tool for a while and got a completely unexpected result. By optimizing with a target of 50 ohm feedpoint impedance, but allowing free positioning of the elements along the boom, the result was like this (4 el version vertically polarised at 4m agl) :

The first “director” is very close to the driven element but is not electrically connected

The results for this simulation are

SWR - 1.32:1 @ 50 ohm (actually 66R + 2jX)
F/B ratio - 14dB
Forward gain - 11.3 dBi

Which is about where I’d expect to be with a 3-element conventional Yagi with z-match
The az and el plots look nice too

I have built a 6 element version and then reduced it to 4 element to make it easier to handle. It works !
So, after this marathon post, the question is : is this (a) new (b) crazy or (c) something everyone but me already knows about ?



Looks good Rick. Do you have any photos of the actual item?

I have a diamond antenna at home that is of similar design. I will check the dimensions and report back.

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Well known Rick. Sotabeams SB5 does this. Also see DK7ZB designs too.


Hi Fraser

The actual dimensions are these

Length (mm) Along boom (mm)
Reflector 1003 0
Driven 980 175
1st director 946 210
2nd director 873 800

The centres are 3d printed and slide along the boom for assembly

EDIT : all-up weight is just on 1Kg


I’m not surprised, just pleased to have found this independently and serendipitously :slight_smile:


My diamond 2m yagi has the following:

97cm driven element
6cm gap
87cm element in front

It has many other elements and a reflector but it was getting dark when I got home and I didn’t want to disturb the neighbourhood!

That weights 10 times as much as my 4 element 2m beam. Yours looks very robust and professional though. Mine wouldn’t be suitable for a permanent installation.

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Hi Rick,
Congratulations. Your systematic approach has rediscovered a known matching method. DL6WU popularised this a while back. Have fun.


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