144MHz 10 Element Long Yagi

There was a need to update the 2m antenna on our local club station.
We decided to replace the 10 element gamma fed 144MHz Yagi, with two vertically stacked
10 element Yagis.

The idea was to build one of Justin's, G0KSC OWL designs,
but unfortunately the aluminium material I had at home did not match any of his simulations.
So instead I had to make a new simulation using his 10 element OWL design as a starting point.

Using MMANA-GAL, this was my final simulation result.


I am excited to start building this antenna.

The antennas are going to be put up in an 18m high tower, vertically stacked 3.2m apart.
Further tweaking was done to maximize gain. Maybe I was overdoing things again....

In practice when building an antenna at home, it is very difficult, no matter how meticulous
you are, to make the antenna exactly as the one in the simulation.
Drilling holes, element lengths etc will vary in about 0.5mm or so, and the pattern will no longer
be the one that was done in the simulation.

Anyhow, the below plot shows the tweaked antennas.
The lower antenna is placed at 18m and the second stacked 3.2m apart.




Building the antennas
As mentioned earlier, to keep the cost as low as possible the simulation was done so I could use the aluminium material I already had at home.
A little more gain could probably be squeezed out using thicker elements for the radiators.

However, I think it will be Ok even if the antennas according to the simulation are very narrow banded. They probably will be within 1:1.15 400 kHz.

Element size and spacing



BOM List (One antenna)
- 6m 25x25x2mm Square aluminium tubes for the boom.
- 1m 20x20x2mm Square aluminium tubes to join the boom parts.
- 1.1m 10x1.5mm for the reflector element.
- 2m 8x1.5mm for the folded dipole.
- 8pcs of 1m 6.0mm aluminium rods.
- 20 clips, element holders.
- 20 6mm stainless steel screws and nuts.
- Connection box to connect coax to the dipole.



Reflector and director elements cut for the antennas



Booms with element holders put in place


All elements except for the T-match are mounted

The folded dipole
In the past I have always built my antennas with a gamma matched feed point.
It has always worked well for me in monoband single antenna configuration.
According to the information found on the internet the gamma feed point is nowadays
less used because of its asymmetric behaviour. I will use a folded dipole feed instead.

    Picture showing RF Choke and folded dipole connector box.

    The finished 10 element Yagi put up for test.

    Two antennas finished and ready to be put up at SK7IJ's contest site.

It was a lot of work and I am quite happy with the result.

I forgot to save the SWR plots from my nano-VNA for the blog, but for what I can remember the
SWR-plot was very close to the one in MMANA-GAL simulation.

I will measure the antennas again when we have put them up in the tower at our club QTH and post them here.

Until then 73's