Negative impedance converters (NICs) in the design of small and multifrequency antennas

Small antennas usually lack of some problems such as their associated bandwidth and efficiency. Metamaterial particles have been used as a means to achieve small antennas. However all the designed antennas with metamaterial particles suffer from the previous drawbacks. The use of the so called active metamaterial particles tries to overcome the previous problems. Negative impedance converters can be a way to increase the bandwidth and efficiency of the small antennas based on metamaterials.