Here is what I found out purely by accident regarding getting channels in an RV. And some knowledge from the TV repair guy. Yup even with the new throw away flat screens there still ARE some local TV repair shops that will work on them if the part is cheaper than a new TV!
First of all each TV will have it's own type of antenna reception circuit boards. Some have great ones, some not so great.
Parked in same spot, TV put in exact same spot inside:
MY one TV will get 7 channels the other only 3.
And Size does NOT matter because it is the teenie tiny flat screen TV that got the more channels! :W
This is what I think the main problem is for us RV'ers using an antenna:
These flat screen TV manufacturer's figure '99% of the consumers today are hooking up their TV's to cable/sat.....so there is NO need for the manufacturer's to put an expensive antenna reception board on their TV's.
I took the TV that only got 3 channels and had the antenna connection board replaced at the TV repair shop and now it gets more channels.
In my winter home in Florida which is remote I hooked up the TV inside the house to my MH antenna. Got a couple of channels.
Went out and bought a 50 dollar antenna at Wallyworld that looks like a 8x10 piece of plastic. Slapped it on the wall inside and get over 10 channels, go figure!