I often think about making one out of copper water pipe tubing soldered together. Just haven't gotten around to it.
I would just go with a standard 3 element horizontal. Like a maco or something.
So I'm betting the 11x of maco vquad is probably about 9x accounting for most the variables?
If you want to talk to your neighborhood mudducks then by all means mount it vertical. I was assuming the man was a skipshooter so i said horizontal. Local talking, hahahaha.I would never install a beam for the 11 meter band on the Horizontal side.It kills all local & mobile signals by about 20 db due to the difference in polarity.A vertical beam works great for Skip since when the signal bounces off of the ionosphere it changes polarity many times.Why limit your signals when you can have both worlds available? I also would avoid the V-Quads like they were the Plague.I had one & I hated it so badly I gave it to a friend who purchased the stacking kit so he could stack it with the one that he had to improve it.He got disgusted with them & threw both of them away because they SUCKED.so badly.We both ways of mounting them & they still were Terrible.My Starduster M-400 & Super Scanner both worked far better than the V-Quads even the stacked ones.
11X is equal to 10.4 dB. of directivity, no telling what they claimed for gain. multiply the amount of tx power actually delivered to the antenna by the power multiplier ratio to get an idea of effective radiated power, less antenna efficiency of course. the v-quad is a fairly efficient antenna.