In brief - Unlimited range

21 May 2012

Electrical characterisation of liquid crystals at millimetre wavelengths using frequency selective surfaces
Electron. Lett. -- 24 May 2012 -- Volume 48, Issue 11, p.611–612

R. Dickie (1), P. Baine (1), R. Cahill (1), E. Doumanis (1), G. Goussetis (1), S. Christie (1), N. Mitchell (1), V. Fusco (1), D. Linton (1), J. Encinar (2), R. Dudley (3), D. Hindley (3), M. Naftaly (3), M. Arrebola (4) and G. Toso (5)
(1) Queen's University Belfast, Institute of Electronics, Communications and Information Technology (ECIT), Belfast, United Kingdom
(2) Universidad Politecnica de Madrid (UPM), ETSI Telecomunicacion, Madrid, Spain
(3) National Physical Laboratory, Time, Quantum and Electromagnetics Division, Teddington, United Kingdom
(4) Universidad de Oviedo, Electrical Engineering Department, Group of Signal Theory and Communications, Gijon, Spain
(5) European Space Agency, Antenna and Submillimeter Wave Section, AG Noordwijk, The Netherlands

The accurate measurement of the permittivity, loss tangent and dielectric anisotropy DC bias dependence for two different liquid crystal (LC) materials in the frequency range 140–165 GHz is described. The electrical characteristics are obtained by curve fitting computed transmission coefficients to the experimental spectral response of a new class of electronically reconfigurable frequency selective surface. The periodic structure is designed to yield bandpass filter characteristics with and without an applied bias control voltage in order to measure the tunability of the LC material which is inserted in a 705 µm-thick cavity.

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