Why am I getting poor reception on my Galaxy Note 4?

I have Sprint. I used to have a Galaxy Note 3. I was forced to upgrade to a Galaxy Note 4. On my Note 3, I had damn near perfect voice, 4G data, and gps reception. However, when I upgraded to a Note 4, I noticed that I only had about 1 sometimes 2 bars if lucky. Calls are getting dropped on my Note 4 constantly. Data for the most part is unaffected. However, I rely on my gps on my phone for my job and I almost never can get a signal for my gps on my Note 4 but I never had a problem on my Note 3. Could it be a manufacturers defect? Ive also heard that the SIM card for the phone might be to blame. Its been like this since the day I got the phone at the Sprint store. Clearly its not the Sprint network but the phone. Or, could I not be understanding something here? Thank You for any info you can provide to me