Gain enhancement of terahertz patch antennas by coating epsilon-near-zero metamaterials

Abstract

Abstract In this work, we propose a novel approach to enhance the gain of a terahertz patch antenna by coating an epsilon-near-zero (ENZ) metamaterial superstrate. The ENZ metamaterial is composed of indium antimonide (InSb) and silicon dioxide multilayers, of which the out-of-plane component of the effective permittivity is close to zero. Results show that by coating the ENZ superstrate the peak gain of the antenna is increased from 5.37 dB to 7.79 dB, corresponding to 45% gain enhancement and greatly improved radiation directivity. We find that the ENZ frequency of the multilayer metamaterial equals to that of semiconductor InSb and thus it can be tuned dynamically. We expect the concept of adding a multilayer ENZ metamaterial superstrate to enhance the antenna gain will find potential applications in other types of terahertz antennas and in antennas in other frequency regimes.