The retrieval of dielectric constants for liquid crystals using open-ended waveguide method based on simulated annealing

Abstract

In this paper, we present a retrieval method of the dielectric constants of electrically controllable unit cell based on liquid crystals (LCs) using open-ended waveguide by simulated annealing. The reflection coefficient is measured from unit cell based on LCs at the end of open-ended waveguide. This measurement setup is similar to the waveguide simulator, which makes the measurement result very suitable for the design of reflectarrays. The dielectric constants are reconstructed by minimizing iteratively a cost function related to the difference between the measurement and the estimation calculated from forward model that is repeatedly updated. And then, the dielectric constants of a mixed LC material TEB30A at six different voltages are obtained using this method. At last, the dielectric constant of TICONIC TLY-5 is retrieved to verify this method, and the result shows good agreement with the known value.

Keywords:

• Liquid Crystals (LCs)
• reflectarray antennas
• simulated annealing (SA)
• opened waveguide
• permittivity reconstruction