Well this is the conclusion after having bit of a play and a fiddle with this 3 element Yagi that I built based on VK5JST build notes. For a 3 element Yagi it is rather directional of about 45 degrees, and very deaf at the back which is a good thing for some setups. Overall it is a rather unusual design with characteristics of much larger Yagi’s for the same band. I have been able to get 1.2/1.3-1 SWR on my Yagi for 146Mhz which I am rather chuffed with and had a good QSO into the VK5RHO repeater from my place. I could probably get better SWR if had a network analyzer to see exactly what the Yagi is doing over 144-148Mhz 2M amateur band.
This Yagi was well worth the time it took to build.