Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Microwave Transparent Metamaterials and Their Applications

마이크로파 투명 메타물질과 응용

  • Eun-Joo Lee (Department of Applied Physics, Kyung Hee University) ;
  • Ji-Ho Yi (Department of Applied Physics, Kyung Hee University) ;
  • Ho-Jun Lee (Department of Applied Physics, Kyung Hee University) ;
  • In-Sung Jeon (KRS Co., Ltd.) ;
  • Sun-Kyung Kim (Department of Applied Physics, Kyung Hee University)
  • 이은주 (경희대학교 응용물리학과) ;
  • 이지호 (경희대학교 응용물리학과) ;
  • 이호준 (경희대학교 응용물리학과) ;
  • 전인성 ((주)케이알에스) ;
  • 김선경 (경희대학교 응용물리학과)
  • Received : 2025.09.05
  • Accepted : 2025.09.17
  • Published : 2025.10.25
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Abstract

Maintaining transparency of protective radar covers in adverse weather is essential for autonomous driving, yet combining high microwave transmittance with low sheet resistance in transparent heaters is constrained by the Fabry-Perot resonances set by a fixed cover thickness. To address this issue, a single metal (e.g., Cu) layer for a microwave-transparent metamaterial with a high metal filling fraction is proposed and experimentally validated. In the W band (75-110 GHz), ultrathin patterned metal imparts a precise phase delay that satisfies the Fabry-Perot resonance condition at target frequencies. By tuning the structural parameters, the transmission resonance is shifted continuously across the band while preserving high peak transmittance. Heating tests at -20 ℃ achieve complete deicing within 9 seconds, demonstrating practical suitability as a microwave transparent heater. To clarify the physical principle, the effective permittivity and permeability are retrieved from the full wave simulation, and an effective-medium model is constructed. The model reproduces the transmission spectra within the W band, substantiating the phase-control mechanism. This approach provides a practical route to dispersion-engineered transparent heaters for radar applications, including autonomous driving.

본 총설 논문은 자율주행 레이더용 투명 히터에서 필요한 낮은 면저항과 높은 마이크로파 투과율 사이의 상충과, 커버의 고정 두께와 유전율로 결정되는 파브리-페로 공진 제약을 동시에 해결하기 위해 금속 충진율 70% 이상의 단일층 Cu 기반 투과형 마이크로파 메타물질을 제안·실증한 결과를 해설한다. 제안된 초박형 금속 형태의 마이크로파 메타물질은 원하는 W 대역(75-110 GHz) 주파수에서 정밀한 위상 지연을 부여하여 파브리-페로 조건을 완성한다. 메타물질을 구성하는 구조 변수의 조절을 통해 공진 투과 주파수의 연속 천이를 확인하고, 각 공진 주파수에서 -0.5 dB 내외에 이르는 높은 마이크로파 투과를 검증하였다. 또한 -20 ℃ 환경의 발열·제빙 시험에서 높은 금속 충진율의 마이크로파 투과 메타물질이 수 초 이내에 완전 제빙을 달성하여 투명 히터로서의 실용성을 입증했다. 아울러 유효 매질 이론에 기반한 유효 유전율·투자율 추출과 등가 단일 매질 모사를 통해 관측된 투과 스펙트럼을 정량 재현함으로써 동작 원리를 뒷받침함을 확인하였다.

Keywords

Acknowledgement

한국연구재단 정부지원사업(Grant no. Rs-2023-00207966).

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