Description
Two experimental devices which exploit the dielectric anisotropy of Liquid Crystals have been designed, fabricated and tested at frequencies above 100 GHz:
i) A phase agile polarizing mirror which converts an incident slant 45 degree signal upon reflection to right hand circular, orthogonal linear or left hand circular (LHCP) polarization depending on the value of the voltage biasing the LC mixture. The polarisation converter is designed to work in a frequency band centred at 130 GHz
ii) An electronically tunable Liquid Crystal (LC) reflectarray which exhibits a large phase range, bandwidth enhancement and beam scanning.
An accurate electromagnetic modelling procedure has been developed for the analysis and design of the antenna, and the simulations show an excellent agreement with the measurements.
The LC-reflectarray (54x52 cells) has been measured in three configurations:
1) In a quasi-optical bench to show the phase range and losses of the cells, providing an 8% bandwidth around 100 GHz and 330º of phase range.
2) As a single antenna where an electronic beam scanning in one plane with an angular range of 60º and a bandwidth of 8% (from 96 GHz to 104 GHz) have been achieved.
3) And as subreflector in a dual-reflector configuration (shown in the figure), designed to provide an electronically steerable beam in a range from -8º to +6º in elevation with 30 dBi of gain.
