Tunable bandpass filter based on epsilon-near-zero metamaterials using liquid crystals

ABSTRACT

In the article, a design method of tunable bandpass filter based on epsilon-near-zero (ENZ) metamaterials using liquid crystals (LCs) is proposed. Thanks to the strong and directionally consistent electric field distribution caused by energy tunnelling effect of ENZ metamaterials, the ENZ unit cell with filled LC in the narrow tunnel can theoretically achieve the bandpass filtering characteristic with a large tuning rate. On this basis, a third-order LC-based tunable bandpass filter is constructed by three series unit structures, which achieves obviously tunable bandpass filtering characteristic with different external biased voltages. Finally, one prototype is designed, fabricated and measured, respectively. The measurement results show that the proposed bandpass filter based on ENZ materials with LCs can achieve effective tuning of the operating frequency with different external biased voltages, which verifies the effectiveness of the proposed design method. In addition, the impact of shape variation of the proposed ENZ-based tunable filter on electromagnetic characteristics is also further discussed and analysed in experiments, which is of great significance for achieving RF miniaturisation and high integration.

GRAPHICAL ABSTRACT

KEYWORDS:

• Tunable bandpass filter
• liquid crystal
• epsilon-near-zero metamaterials
• microwave component

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant No. 62201612 and No. U22A2014, China Postdoctoral Science Foundation under Grant No. 2022M723880, Natural Science Foundation of Shaanxi Province under Grant No. 2023-JC-QN-0740, and Open Fund of Shaanxi Key Laboratory of Artificially Structured Functional Materials and Devices under Grant No.AFMD-KFJJ-22104.