A simple 3 ele yagi for 144Mhz
Here is a simple 3-element yagi for 2 metre band portable working, which was made-up from an old Band 2 FM antenna.
 Construction notes:
The reflector and director are touching the metallic boom in the centre.
A coaxial matching stub is used to match the driven element to 50 ohm due to the coupling effect of the other elements.
Attach a length of approx 20cm RG58 coax at the feedpoint of the dipole (in parallel with the feeder cable and leave it open ended).
Some trimming will no doubt be needed of the matching stub for best match. I find it best to star off with a slightly longer length than required and trim by 5 mm each time. It is essential to trim by 5mm because the exact point of matching is quite narrow.
Expect 7db forward gain from the antenna.
You may vary the length of the driven element slightly and it will not impair performance, but you will have a slightly different length needed for the tuning stub.
73 de Andy G0FTD
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