Let me preface this by saying I am no expert on this digital reception thing. For that matter we are all pretty green. Some of my knowledge of antennas and RF transmission/reception from my analog days seems to apply to DTV OTA reception but the relative importance of some factors like signal strength and multipath seem to be different so the perfect setup is not necessarily going to be what worked well for analog.
Based on my recent learning it seems that signal quality (absense of multipath interference from the source) is much more important in DTV than in analog. Absolute signal strength and (perhaps) adjacent channel interference is much less important in DTV.
So, the idea of adding electronic gain to an antenna - which was a popular way to improve fringe reception with analog - may not help. In fact it may make matters worse since amplification is indiscriminate and will increase the levels of delayed (miltipath) signals just as much as the early direct signal. On the otherhand, very high directivity antennas with high side and rear rejection should make things better. The problem picking antennas today is that most are specified according to a gain figure and no 3d polar plots of the "gain" are provided - which would give us a good idea of an individual antennas directivity.
Since most of the UHF antennas available are not tuned to a single frequency which would allow quite high directional and gain charateristics, they are broadly tuned to permit fairly uniform "gain" across the UHF TV band. This compromise reduces gain and directivity considerably, essentially allowing more signal in from other directions than the source.
There are ways to improve a broadly tuned antenna in this regard but the easiest 2 solutions to us consumers is to try to find a good directional antenna - for instance the anectdotal info in this forum regarding particular successes with antennas is a good source, and you seem to have chosen one of the recommended antenna - then experimenting with location of the antenna (height as well as where on a lot it is sited). In this case higher may not be better, since it is multipath reduction and not simply signal strength increase you are looking for.
I will give you an example. My bow-tie is really an outdoor antenna. I initially set it up indoors, behind an outside wood basement-level door that generally faced the direction of the towers. After a bit of turning, I was able to get all the DTV stations with very high and stable quality numbers. This was to be a temporary setup until I could go outside and site it on the roof. I moved the antenna last weekend to the site on the roof of my previous 2 antennas and what I found was a significant reduction in the stability of the quality numbers on DTV and more visble ghosting on 44 analog. So the antenna is back in the basement for now. Obviously the low height and earth/masonry features that the antenna "sees" from the basement position are of more help than harm and getting it up where it is really line-of-site to the towers is also making it more exposed to some reflections. Of course the more exposed downlead from the rooftop could be contributing but it is quad shielded RG-6 which is about as good as it gets so I have to live with whatever it is capable of.
Good luck "tuning" your setup.
