thx for your replies. My two main goals are:
1) to loft above (or as close as possible) a wall of pine trees behind our house in the direction of all wanted stations. So to answer one question, yes, all stations are in one narrow directional beam.
2) stations are also fairly far away, in the 30 - 45 mile range and are VHF in addition to UHF. I'm hoping to find a configuration that -- like the CM 4228 -- might take in VHF high band with the two 4221s.
I'm also experimenting, because it's fun and a challenge, but I'm not too technically versed in this stuff. Learning as I go.
And lastly, I'm doing it on a budget. I have two CM 4221s so that's what I'm going with, for now. I might add a Winegard YA-1713 if I can't get high band VHF with the 4221s. As a last resort I will rig up a side-by-side arrangement to make a homemade 4228 if that turns out to be best for my situation.
I did a little more on my project today and ran into an immediate problem. The 4221 reflector support (non-swaged end) drives through the mast with a metal rod anchored on the other side. It leaves only about an inch of open mast to work with for stacking. Oops. So it won't be so easy to stack, mast atop mast, after all.
My next idea was, "I wonder what might be 'gained' (pun intended) by joining the swaged ends together with a 7-8" joiner mast section and using the two 4221s horizontally spread?" This wouldn't help with topping the pine trees, obviously, but it might help in gain and high band VHF reception. ?
So just to try out this idea I sawed off a seven inch piece of mast and joined them together at the swaged ends. I now have a Channel Master 4221+1224 antenna if you get my drift. I can attach this to another mast with a U-bolt. I'm going to join the two baluns together with equal-length RG6 into a Channel Plus 2532 combiner. If there's a lower loss UHF-type combiner please advise.
Before I do any more though, if any part of this Plan B is fatally flawed I'd like to know in advance. The bow ties will flare vertically instead of horizontally. A problem? The antenna spread will be ultra-horizontal. A problem? There will be slight gap in the bow tie structure (an extra inch or two) in the middle. A problem? Any other obvious pitfalls?
As I say, I'm into experimenting as well as practically solving for my particular situation. If the ultra-wide 4221+1224 has a very narrow beam, that will be ok.
Thanks in advance. Alex
p.s. I plan to bind the reflector screens together with copper wire. p.s. 2, forget about the pine trees in answering whether the horizontal config of two 4221s is feasible or not. The practical consideration is secondary to the theoretical in this case.