depends o the adapter . some of them use both antennas and in your case only one is used. the wire that is taped to the antenna cable is the amp.
connect it up to the remote on wire (blu/wht) or pwr ant ( blu) if you have one.
the whole concept of nissan diversity is that you have two antennas that pick up the signal and via a bit of creative circuitry in the radio they are combined for better reception. some of the upper end sony units had this as an option and they fitted these cars. ( can't remember which ones though.)
let me know if the above helps..