Hi some guests came and broke an antenna off my Asus RT-AC3200. (has 3 wifi bands)

It seemed that while i removed the one broken antenna to be glued back (MacGyver style), all wifi signals and speed were just fine! (did not test max throughput)

So it occurred to me the 6 antenna are not divided equally between the 3 bands? Or are they?

Also where do you buy replacement antenna that doesn't cost me a new router?