Multiband beam (70 MHz)

I have no experience on this matter, so this is a purely theoretical post.

If looking for a directional antenna that covers 50 MHz, 70 MHz and 144 MHz, why not consider a log-periodic? With a boom of 4.5m, max width of 3.6m and 11 elements, three bands are covered. A matching system is needed.

Another version, probably with a better impedance range but lower gain, counts 15 elements over a 5m boom.

So, there's plenty of room to play with. Just need to put to work some simulation software and then cut lots of pipes...