Design and Analysis of Active Metamaterial Modulated by RF Power Level

Ratanak Phon,Sungjoon Lim

doi:10.1038/s41598-020-65318-0

Abstract

In this paper, a radio frequency (RF)-power-modulated active metamaterial loaded with a nonlinear Schottky diode is presented. Its operating mode is a function of the incident power level. It is switched by a change in the operating state (i.e., on/off) of the Schottky diode, which is directly triggered by a change in the incident power level. For instance, when a low-power RF radiation is incident on the proposed metamaterial, the Schottky diode is turned off, and the metamaterial passes a 2 GHz signal in the pass-band mode. By contrast, when a high RF power is incident, the diode is turned on, and the metamaterial reflects all frequencies in the reflection mode. The proposed active metamaterial was analysed by performing numerical simulations for both low- and high-power modes, and the proposed concept was successfully demonstrated by circuit analysis, full-wave simulation, and experimental results.

Highlights

Metamaterials, known as artificial electromagnetic (EM) structures, have received considerable attention owing to their unusual properties, which are not found in nature
The structure of the proposed radio frequency (RF)-power-modulated active metamaterial was designed such that its responses could switch according to the power level of the incident wave
Because the full-wave simulation ANSYS High-Frequency Structure Simulator (HFSS) setup does not support a nonlinear SPICE model for the diode, we considered a simplified RC circuit for the Schottky diode pair

Summary

Introduction

Metamaterials, known as artificial electromagnetic (EM) structures, have received considerable attention owing to their unusual properties, which are not found in nature. Many researchers find the conventional technique of using active components (varactors or p-i-n diodes) to be more reliable and easier to use for realizing metasurfaces with multifunctional characteristics[22,23] since the operating state can be tuned/switched by controlling the external bias. The above-mentioned design can be implemented to achieve self-reconfigurable or power dependent characteristics by designing with additional sensing circuits[26,27] These metasurfaces require a biasing configuration and an external power source to control their operating state, rendering them costly and difficult to design. Power-dependent metasurface that absorbed high-power but not low-power surface waves[29,30] On another hand, a metamaterial-based nonlinear multiconductor transmission line is reported that achieves broadband switchable between transmission and reflection modes[31,32]. When a high-power RF wave is incident, the diode turns on, and the proposed metamaterial reflects all frequencies since it is in the reflection mode (Fig. 1(b))

Methods

Results

Conclusion