HOA's, Neighborhood assocaitions, basically noone can prevent you from putting an antenna outdoors -- If you live on base at Wright-Patt, there may be some add'l concerns, however. Also, I don't believe it has to be "concealed" either --
FCC has a ruling(it's the law) on this, you can go up to 12' above your roofline. I'm not sure, but I do think HOA's etc. can have control over mounting issues where safety/etc. issues are concerned. Info avaialble in the OTARD document at FCC site(link provided in below threads), as well as all over AVSforum. Here are a couple of recent, useful threads on this issue:http://www.avsforum.com/avs-vb/showt...hreadid=249023http://www.avsforum.com/avs-vb/showt...hreadid=280276
Welcome to AVS!
Kevin is right on the money. Every situation is different, there are many factors involved. It's difficult to predict what you may need in your circumstance, and as you can see from Jon's report, getting good reception can often be quite easy. I probably tend to overestimate what may be needed, as I assume(perhaps incorrectly) that folks will want to receive as many stations as is reasonably possible, as well as to have the best reception possible.
Concerning Dayton/Cincy antenna aiming for your location, I checked, and Cincy towers would be 215~218 deg. heading, most at 46~48 miles from "center" of Beavercreek, and Dayton Towers are ~10 miles on a bearing of 278~283 degrees -- That's over a 60 degree difference, and you'll definitely want to use a good, Hi-gain directional antenna for Cincy(aimed right at Cincy towers), so it's probably going to be too much of a spread, and you'll probably want a rotor -- Especially, also since Columbus(77~79 deg. ENE)/Chillocothe(104 deg -ESE) stations also may be within your reach at 50~57 Miles. The Chillocothe station, WWHO-DT(~50 miles from you) has WB HD, and probably will have UPN HD too when it becomes available, none of the Dayton/Cincy stations currently offer WB HD.
Probably a good idea though to try it and see how it works via "manual rotation by hand"(if necessary) first, before getting a rotor. Also, another possibility is to use seperate antennas on seperate feedlines for the stations in different markets selecting between them with a a/b switch placed near your receiver. They even have a/b switches with remotes, BTW.
And yes, it should help your analog reception, and the better you can get the analogs in, the better shot you have at getting good reception from the Cincy/Columbus digitals.
You are "almost" fringe area for Cincinnati though, and most likely definitely fringe area for Columbus -- And keep in mind, issues such as terrain blockage can be an issue, especially if the "hills" are very nearby your location. If you don't have a terrain issue though, with the "Right" antenna setup, you should be able to get reception of Dayton/Cincinnati, and very possibly Columbus stations, too.
It's difficult to say "how much" or, what antenna you will need/will work beest as every situation can be different, but IMO, IF at all possible, in your situation, IF you want more than just the Dayton station it is Probably best to go with the "most directional" highest-gain of antennas, and mount your antenna(s) as high as you reasonably can -- Increased directivity is probably Especially important since, given your location, you might experience some co-channel interference issues with the following stations that are on the same channel(DT at the end of the callsign denotes a digital/HD station):
WBNS 10 CBS Columbus - WCPO-DT 10 ABC Cincinnati
WCMH-DT 14 NBC Columbus - WPTO 14 PBS/ThinkTV Oxford
WTTE 28 Fox Columbus - WPTO-DT 28 PBS/ThinkTV - Not yet on air, will be broadcasting from a tower in Cincy
WOSU 34 Columbus - WCET-DT 34 Cincinnati
Hopefully, your chimney will be in a "sweet spot" for good reception, as sometimes, moving the antenna a little horizontally can make as much, or more difference than up or down. If you can, It's probably a good idea to try a little experimentation with different antenna placement to see what you get before mounting it "permanently". Even on a short mast a bit off the ground may tell you a lot.
For the digitals currently, you'll need an antenna with VHF capabilities for WSYX-DT 13 ABC Columbus, and WCPO-DT 10 Cincinnati, the rest of the area digitals currently are on UHF --- Many analogs in the area are also VHF, and probably after analog shut off more digitals will be on VHF. Seperate VHF/UHF antennas usually offer the best performance, but there are good VHF/Combo antennas out there as well -- Only problem is, the best of VHF/UHF combo antennas are quite large(for TV antennas), and if you use these, you'll want to make sure you have a sturdy mount to account for wind/ice loading.
Concerning your multiswitch/amp, you could try it, but what would likely work better for Cincy/Columbus stations would be to use a completely seperate feedline for your OTA antenna, and a hi-quality, mast mount preamp such as a CM7777. Power supply for these goes inside, and DC power feeds the mast-mount preamp(put it as near the antenna as possible). You might run into some problems with Preamp overload from the Dayton stations though, and either an adjustable attenuator in-line, or even better a seperate Lo-gain antenna for Dayton on a seperate feedline might not be a bad idea if you do experience overload. However, I can tell you I'm 12 Miles from the tower, and Preamp overload isn't a problem here.
Probably best to try it without the preamp first, and see what sort of reception you get.
Finally, If you haven't already done so, you can punch your address/etc. at the following site, and it will give you a good idea of the stations you should be able to receive, as well as make recommendations on what sort of antenna you need, and if you might want to use a preamp.http://www.antennaweb.org
IMO however, it's probably not a bad idea to go a "step or 2 up" from what antennaweb recommends for the "weakest" station you want to try to receive.
Lots of great antenna and reception info here:http://www.kyes.com/antenna/antennadex.html
And, info on many antennas/preamps/etc available(you can buy them from here too) here:http://www.starkelectronic.com/allant.htm
I Know that's a lot, but hopefully some of it helps,
Good luck and let us know how it goes,