TY - JOUR
A1 - Nova, Vicente
A1 - Bachiller, Carmen
A1 - Villacampa, Belén
A1 - Kronberger, Rainer
A1 - Boria, Vicente E.
T1 - Characterization of Nematic Liquid Crystals at Microwave Frequencies
T2 - Crystals
N2 - The use of nematic liquid crystal (LC) mixtures for microwave frequency applicationspresents a fundamental drawback: many of these mixtures have not been properly characterizedat these frequencies, and researchers do not have an a priori clear idea of which behavior they canexpect. This work is focused on developing a new procedure for the extraction of the main parametersof a nematic liquid crystal: dielectric permittivity and loss tangent at 11 GHz under differentpolarization voltages; splay elastic constantK11, which allows calculation of the threshold voltage(Vth); and rotational viscosityγ11, which allows calculating the response time of any arbitrary device.These properties will be calculated by using a resonator-based method, which is implementedwith a new topology of substrate integrated transmission line. The LC molecules should be rotated(polarized) by applying an electric field in order to extract the characteristic parameters; thus,the transmission line needs to have two conductors and low electric losses in order to preserve theintegrity of the measurements. This method was applied to a well-known liquid crystal mixture(GT3-23002 from MERCK) obtaining the permittivity and loss tangent versus bias voltage curves,the splay elastic constant, and the rotational viscosity of the mixture. The results validate the viabilityof the proposed method.
KW - Nematische Phase
KW - Nematic liquid crystal
KW - Permittivity
KW - Loss tangent
KW - Splay elastic constant
KW - Rotational viscosity
KW - Microwave
KW - Dielektrizitätszahl
KW - Elastische Konstante
KW - Mikrowelle
Y1 - 2020
UR - https://epb.bibl.th-koeln.de/frontdoor/index/index/docId/1641
UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:832-epub4-16419
SN - 2073-4352
VL - 10
IS - 12
PB - MDPI
ER -