144 MHz 10 element Yagi antenna

I have bought an Yagi antenna from www.radio-shop.cz, model ZY144-10. The supplied documentation is brief, just instruction for assembly, but without details I expected (mechanical dimensions, list of components, radiation pattern, SWR,...). I don't want to put antenna on tower without having solid documentation, at least because I would like to be able to repair it in case something is broken. So here is my documentation, NEC file used for antenna simulation and some simulation results.

First impression is good, seems to be robust enough. Just one thing - the radiator is just simple dipole, that means it is symetrical, but is directly fed by coax cable, without any kind of balun. It must result in some mantle current... So I better prepare some balun in advance in order to avoid problems.
73 DX