antenna cable

Just purchased used 2010 xb. Has pioneer aftermarket radio. Reception is awful. Removed radio and found that antenna cable had been cut and spliced but there is a red and a black wire in the factory cable that is not connected. Is this an amplified antenna? Can get a new cable from Scion for $73 that connects under the carpet, I think. But I am not sure if this new cable will fit my radio. Maybe that is why it was cut. Anyone had this problem. Thanks in advance.