Wideband direct antenna modulation using high-Q antennas

Wireless communication techniques have been broadly developed during the past decades due to their extensive applications. One required characteristic of most wireless systems is a wide transmitting bandwidth through a small-size antenna. Although there have been lots of studies on different techniques to broaden the bandwidth of the small antennas, the antenna bandwidth is strictly ruled by the fundamental physical limit. It is well-understood that in linear time-invariant (LTI) structures, antenna bandwidth is in contradiction with the size and hence, small-size antennas suffer from narrow bandwidth. This problem becomes significant when a high-rate data-transmission is required along with a very small-size antenna.