Internal parts of HTC One M8

[Jugga151]

Hey devs, I'm replacing the battery in one of my old HTC One M8's, and while inside it and online ordering the battery, i noticed these extra antenna ports that weren't being used, and on the international version of this phone, the charging board doesn't have one of these ports. So I'm just curious if anyone can explain what they are and what they are used for. Any help or info would be nice, I'm interested in learning all i can about them from hardware/firmware clear down to sine waves/frequencies and so forth. I'll upload some pics of what I'm talking about too here shortly.