Recent Progress on Metamaterial-inspired Antennas

Many attributes of metamaterials have led to the consideration of engineering metamaterialinspired structures for a variety of applications. This includes the miniaturization of resonators and their use for improving the performance characteristics of electrically small antennas from the microwave region up through to the optical region. Achieving higher directivity from electrically small antennas by introducing structured ground planes has been considered successfully. Active metamaterial constructs have been introduced to increase the bandwidths at low frequencies and to overcome the losses at high frequencies. They have led to recent non-Foster antenna designs which have some preliminary experimental results. Thus the development of an efficient, high directivity, large bandwidth electrically small antenna is rapidly becoming a possibility.