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oe1(光电查) - 科学论文

3 条数据
?? 中文（中国） ▾

  • Low-profile wideband circularly polarised single-layer metasurface antenna

    摘要： A novel low-pro?le single-fed circularly polarised single-layer metasurface antenna for wideband operation is proposed in this Letter. The metasurface antenna consists of nine unit cells arranged in a 3 × 3 layout. Four slits are incorporated into four of them, respectively, to form two orthogonal currents with 90° phase difference; hence, circularly polarised ?elds are excited. Moreover, a modi?ed L-type slot is etched on the middle lattice to improve impedance bandwidth and axial ratio performance. The proposed dielectric-?lled (?r = 3.5, tan δ = 0.001) antenna with a low pro?le of 0.038λ0 (λ0 is the working wavelength at 5.7 GHz in free space) achieves about 18.0% measured ?10 dB impedance bandwidth. The measured 3-dB axial ratio bandwidth of the proposed antenna is about 12.8% (5.35–6.08 GHz) with a broadside gain of more than 6.9 dBi.

    关键词： low-profile,metasurface antenna,wideband,circularly polarised,single-layer

    更新于2025-09-23 15:21:01

  • Circularly polarised antenna with wide harmonics suppression by two angled C-shaped structures

    摘要： In this Letter, a circularly polarised (CP) antenna is proposed. The proposed antenna is realised by combining two angled C-shaped structures. By setting different widths (WL and WR) for the left and right angled C-shaped structures, respectively, an asymmetric structure is obtained. Therefore, the proposed antenna exhibits CP characteristics. From repeated simulation results, the authors find that the optimum ratio WL: WR to make the proposed structure operate as a CP antenna is 5: 8. Moreover, the measured reflection coefficient is lower than ?2.4 dB within a stopband up to 12 GHz. This means that wide harmonics suppression (up to the fifth harmonic) is successfully achieved.

    关键词： C-shaped structures,harmonics suppression,circularly polarised antenna

    更新于2025-09-12 10:27:22

  • Recent advances in the manipulation of circularly polarised light with cellulose nanocrystal films

    摘要： Significant advances have been made to control the iridescence and the selective reflection of left circularly polarised (LCP) light, and transmission of right circularly polarised (RCP) light of solid films prepared from cellulose nanocrystals (CNCs). However the manipulation of the photonic properties of the CNCs films, which reflect both RCP and LCP light is less investigated. Solid films prepare from natural sources as CNCs have advantageous characteristics that are absent in other synthetic structures, such as wide availability and renewability. Here we review and compare recent research activity involving the production and characterization of photonic band gap structures resulting from an anisotropic layer inserted between two cholesteric layers with different helical pitches but the same handedness. We make connections between systems existing in Nature and synthetic ones with the hope of advancing in the production and manipulation of CNCs-based photonic structures.

    关键词： Cellulose nanocrystals,Photonics,Circularly polarised light,Bio-inspired materials,Iridescence,Liquid crystals

    更新于2025-09-10 09:29:36