A Review on the History and Current Literature of Metamaterials and Its Applications to Antennas & Radio Frequency Identification (RFID) Devices

Metamaterials are artificially engineered novel substances (or matter) that exhibit properties not found in nature. One of the earliest examples of a metamaterial structure is the split-ring resonator. This article is a current review of metamaterials, what it is, its classification, and its applications towards the field of antennas and radio frequency identification (RFID) devices. There are two major types of metamaterial antennas: leaky-wave antennas, and resonant antennas. Antennas can be made from composite right-left handed metamaterials, or antennas can be loaded with a metamaterial screen such as a shelled electrically small antenna (ESA) fed by coax. Metamaterial resonators can aid in reducing the antenna size, help improve the gain, improve the directivity, improve the return loss, and control the radiation pattern (by loading the antenna with a tunable unit). Recent advances in printing and fabricating technologies have allowed for use of metamaterial antennas in wearable gadgets and textiles; and can be used in conjunction with RFID devices and tags to advance and aid (emergency) equipment used by first responders.