Microstrip Device for Broadband (15-65 GHz) Measurement of Dielectric Properties of Nematic Liquid Crystals

The essential dielectric properties, the basic alignment techniques, and the common measurement methods of the nematic liquid crystal (LC) at RF are briefly reviewed. A new device for the broadband measurement of the dielectric constants and loss tangents of nematic LCs at microwave and millimeter-w...

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Bibliographic Details
Published in:IEEE transactions on microwave theory and techniques 2015-04, Vol.63 (4), p.1388-1398
Main Authors: Deo, Prafulla, Mirshekar-Syahkal, Dariush, Seddon, Lawrence, Day, Sally E., Fernandez, F. Anibal
Format: Article
Language:English
Subjects:
Broadband communication
Dielectric measurement
Dielectric properties
Dielectrics
Frequency measurement
liquid crystals (LCs)
Microelectronics
Microstrip
microstrip lines
millimeter-wave tunable devices
Scattering parameters
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Summary:The essential dielectric properties, the basic alignment techniques, and the common measurement methods of the nematic liquid crystal (LC) at RF are briefly reviewed. A new device for the broadband measurement of the dielectric constants and loss tangents of nematic LCs at microwave and millimeter-wave frequencies is presented. This device whose specification and fabrication are outlined is essentially a two dielectric layer microstrip structure with coplanar-waveguide terminals, which is easy to fabricate. Compared to previous structures, the proposed device is extremely broadband with 15-65-GHz bandwidth, benefits from a solid exposed ground plane for easy temperature test, and operates under bias voltage. The technique for the extraction of the dielectric parameters of the nematic LC analyzed by this device is explained and the sources imposing the frequency limits on the device performance are identified. Two different nematic LCs, MDA-00-3506 and GT3-23001, are characterized and the results are shown to compare well with those available in the literature. In the comparisons, the maximum difference found for the dielectric constants for MDA-00-3506 is 5% and for GT3-23001 is 5.3%.
ISSN:0018-9480
1557-9670
DOI:10.1109/TMTT.2015.2407328