Can I use 1 wire for TiVo and antenna

I have two cables coming from outside a black one that screws into my Virgin TiVo box, and a brown coax that comes from my ariel . My tv is on the wall and behind the tv is only one virgin cable that is in the wall and this screws into my virgin box on the wall under the TV all works fine but if I turn off the virgin box I don't have any tv because my aerial is not connected because I only have one wire. Question do they sell something I can connect incoming virgin and incoming antenna to one wire, and something for behind TV to make antenna and virgin box separate wires. Or is there an easy way.