Active Metamaterial Antenna with Tunable Zeroth-Order Resonances for Narrowband Internet of Things

Abstract

With unique electromagnetic properties, metamaterials (MTMs) provide more freedom for antenna design, particularly with the combination of active-device-enabling effective tuning. By integrating the active device and the periodical cells of MTMs, the electromagnetic characteristics of individual cells can be manipulated independently, thereby realizing multiple tunable states for MTM antennas consisting of several periodical cells. In this paper, we employ active devices such as PIN diodes to each periodical cell to tune each cell independently, thereby realizing 36 tunable zeroth-order resonances (ZORs) for the metamaterial antenna with three cells in a frequency range of 4.48–5.34 GHz. Moreover, each ZOR has a bandwidth as narrow as 0.09 GHz, indicating that the tunable ZOR antenna can be potentially applied to 5G Narrowband Internet of Things (NB-IoT).