reception issues iPhone 4S

I bought the iphone 4s in february, i would get failed calls, and the phone would not have reception when it should have.I ws told it could be a faulty antenna. I had an android before which had great reception everywhere, never had a problem in my house. Since having the Iphone its a nightmare trying to get continued reception, even in my house-i took it to the apple store 3 weeks ago and they gave me a new phone,The new one is the same-reception is spotty, most of the time in my house only 1 or two bars, takes too long to finally get 3 bars, very rarely do i have a full set , any advice on how to fix this problem? I expected alot more from apple and a phone that costs this much