Can two antennas be smaller than one?

Traditionally all mobile radios and mobile phones have used one antenna common for both transmitting and receiving. For an external whip or stubby antenna this seems like the only practical solution but with the increasing use of internal antennas the number of antenna elements is not necessarily limited to one but rather the total size. On the contrary, it is shown that a number of advantages can be gained by a division of the antenna system into at least two antenna functions for transmitting and receiving. A typical advantage is that the transmitting and receiving function can be optimized separately. Diversity and other additional functions may make even more than two antennas worth considering. For 3G systems with high speed down-link requirements good antenna performance including the diversity function is an important means of enhancing the receiving capacity