There is such a beast, in fact there are a lot of them so I would suggest you go to the search engine of your choice and crank in "Smart Antenna" and first read about what they do, how they work, and such, then hunt the places that have consummer ratings on them to find one that works well. Antenna's of any kind are a strange creature and these are no different, what looks cool, or is the most expensive may not be any better than something low priced that looks great.
Here is link to what they are and should do:
and here is a like to at least one on the market:
As I noted you can find all kinds of them, but unlike analog getting a good enough digital lock to get to an accepable error rate (meaning your TV will allow it through) is a little trickier than with analog.
Most of the better digital antenna seem to have amps in them, where that is the case you may want to pay a little more, building a good RF amp is not easy and not done well by a lot of companies.
However, most important is you look for ratings from people who have bought and used one, and second is get it from a place you can return it to and get your money back. I noticed Amazon is selling them, you will likely pay more but you will be able to return it if it does not help.
Hope this helps, it is not a scam in general, but do your home work!
The Preliminary tests by the CEA R-5 Antenna Standards committee have shown impressive results, finding that a smart antenna can be most effective in ghosty areas and can increase DTV system performance by as much as 12dB. In addition, both the MSTV and the NAB have endorsed the technology, and the NTIA is allowing the interface on converter boxes certified in its DTV coupon program.