A circuit and antenna arrangement includes a diplexer having a single radio frequency input/output interface and dual feed connections with an antenna adapted for use over a plurality of frequency bands. The diplexer has a capacitance connected between the radio frequency input/output interface and the antenna, and further has an additional capacitance that is selectively one of connected or not connected in parallel with the capacitance. In one embodiment the additional capacitance may be a capacitor in series with a switch, while in another embodiment the additional capacitance may be a MEMS variable capacitor.