Does having a SIM card effect your reception?

I currently use straight talk and bought an unlocked iPhone. It uses a SIM card and I feel like the reception isn't as good as well as the internet. If I were to buy an iPhone directly from straight talk would it get better reception?

No that won't have any effect, a locked iphone would be just the same but with a restriction on it, there's no difference other than that.

Well for a GSM phone, no SIM card means no reception. The reception depends on the signal strength available to you where you are.

No has no effect at all. The reception is based on your location and the backbone of the network it's on.

Shouldn't. Sim card is more to id the phone to your carrier. Subscriber Information Module(SIM)

A SIM card should have No effect on the received (Or transmitted) signal strength.