Beats me why yours aren't working well, there must be something wrong with them. They are uhf ONLY though. I have TWO of them up and running right now, and they are excellent antennas! I've had one installed for over 5 years now, and added another for a specific channel that's in a different direction, and included a vhf antenna for my one vhf station.
So, a total of 3 antennas in my array, including a Jointenna device for the two UHF antennas feeding into FM trap (I have strong fm radio stations very close), then a Kitztech KT-200 preamp, then into the uhf side of a UVSJ combiner. My Y10-7-13 vhf only antenna feeds into another FM trap, then into the vhf side of the UVSJ, bypassing the Kitztech preamp. Then the single quadshield rg-6 coax goes to the back of my tv center in the living room, into the power inserter for the preamp, then into two splitters which feeds a bedroom tv set, my living room tv set, and my Tivo.
Everything works perfectly. Though 40 years ago I was a Winegard dealer, and installed antenna systems for part of my living. So, I'm pretty good at getting things tweaked within an inch of their lives.
It took me about a month of tweaking to get this all working 100%, but I have several unique situations in my receive location that needed compensation to get all my stations solid.