Determining dielectric properties of nematic liquid crystals at microwave frequencies using inverted microstrip lines

Peng H., Zhang Y., Zhu S., Temiz M., El-Makadema A.

Liquid Crystals, cilt.49, sa.15, ss.2069-2081, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 49 Sayı: 15
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1080/02678292.2022.2102685
  • Dergi Adı: Liquid Crystals
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Chimica, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.2069-2081
  • Anahtar Kelimeler: effective relative permittivity, inverted microstrip line, microwave tunable device, Nematic liquid crystal
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

In this paper, we have investigated the dielectric properties of nematic liquid crystals (NLCs) by measuring the resonant frequencies of inverted microstrip lines (IMSLs) of NLC being the substrate material at the microwave frequency band. The designed IMSL devices consist of a cavity for NLC mixture between the inverted microstrip line and the ground plane. The anisotropy values of the NLCs were determined by observing the change of the resonant frequency when the strength of external electric fields applied on the NLCs varied. The experiments demonstrated that the effective dielectric constant of the NLC can be manipulated by the proposed devices via external bias voltage for tuning. The accuracy of the method for determining the dielectric constants of JC-M-LC-E7 (JC-E7) and QYPD-036 LCs was analysed with several prototypes based on two separate designs. The high accuracy of 91% in permittivity determination was demonstrated, and the design and fabrication techniques are beneficial for making microwave components of high tunability.