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In-Gon Lee [1] and Yong Bae Park [2] and Heung-Jae Chun [3] and Yoon-Jae Kim [4] and Ic-Pyo Hong [1]

Academic Editor: Muhammad Ramlee Kamarudin

1, Department of Information and Communication Engineering, Kongju National University, Cheonan 31080, Republic of Korea, kongju.ac.kr

2, Department of Electrical and Computer Engineering, Ajou University, Suwon, Republic of Korea, ajou.ac.kr

3, Department of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea, yonsei.ac.kr

4, Agency for Defense Development, Daejeon, Republic of Korea, add.re.kr

Received Jun 25, 2017; Accepted Sep 27, 2017

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Introduction

A frequency selective surface (FSS) is an electromagnetic structure that resonates with a specific frequency, exhibiting a corresponding impedance derived from its capacitance and inductance, and it selectively transmits or reflects the frequency of incident electromagnetic waves [1]. FSSs are currently being applied, for instance, to reduce interference in electronic devices [2] and miniaturize radar cross sections [3]. However, conventional FSSs present a limitation when applied to modern multifunctional and complex systems, as they constitute a passive circuit operating on a single frequency band. To address this problem, researchers have developed the active FSS (AFSS), which can operate on different frequency bands [4, 5].

AFSSs include adjustable elements within their unit cell to vary the equivalent capacitance and inductance. Therefore, they can have various characteristics including resonance frequencies ranging from megahertz to terahertz, adjustable bandwidth, and frequency attenuation based on the control of the operating frequency. The active circuit control to change the frequency response can include elements such as PIN diodes, varactor diodes, radio-frequency (RF) microelectromechanical systems, and other electronic control elements that directly modify the unit cell impedance. There is extensive research on AFSS control using these elements given its ease of construction [6–13]. However, the resulting AFSSs require many active elements to provide a stable frequency response, and they are affected by aspects such as incidence angle and polarization, which complicate the circuit structure [7, 8, 13]. Moreover, a typical AFSS requires, for instance, each of its unit cells to be isolated from the bias circuit and the surrounding unit cells, as well as several...

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