These will adapt your RCA plugs into BNC. We sell them in sets of 5.
White RCA Adapters
Indoor GPS Starter Kit featuring one Modem and five Beacons to get your project running. Accurately position your robot to a couple centimeters indoors! Kit includes one modem, 4 standard beacons and 1 beacon with built in IMU.
900 MHz Rubber Duck Antenna - SMA Male Connector