A reconfigurable antenna based on the liquid crystal technology is presented in this paper. The antenna comprises a planar lower reflector with an incorporated feed at its center and a polarizing grid on top as an upper reflector. The lower reflector is utilized to collimate the beam and to twist the polarization. The polarizing grid selects the polarization for the transmission and reflects the orthogonally polarized waves toward the lower reflector. Combining reflector elements with a polarizing grid allows performing additional phase adjustment on the upper reflector for beam steering. Reconfigurability is maintained by the upper reflector, in which a liquid crystal mixture is used as a tunable substrate. The liquid crystal layer is tuned with a bias voltage configuration to obtain an appropriate phase adjustment for the beam steering. As a proof of concept, the beam steering capability of the antenna is demonstrated by steering the main beam to , 0 , and 6 at 78 GHz. The measured gain at 78 GHz is 25.1 dB. The proposed antenna configuration is a promising candidate for reconfigurable, high-gain, low-profile, and low-cost antennas.Index Terms-Beam steering, liquid crystals, microstrip antenna arrays, microwave antennas, millimeter wave technology, reflectarrays.

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In this paper, we present a continuously tunable phase shifter realized in MEMS technology. Varactors with liquid crystal as a tunable dielectric layer underneath gold bridges are used to build a loaded line phase shifter. Measurements show that the phase shifter has a differential phase shift of 928, a figure of merit (FoM) of 428/dB and an input matching of 219 dB at 76 GHz.The tuning speed of the phase shifter is measured at different temperatures between 10 and 508C. The realized phase shifter can be used in combination with MEMS switches in order to build a 3608 tunable reflection phase shifter.

In this paper we present a frequency tunable patch antenna working in the Ka-band. Liquid Crystals are used as a tunable dielectric layer between a ground plane and an inset feed microstrip patch. Measurements show, that the resonance frequency of the antenna can be tuned continuously from 34.1 GHz to 37.7 GHz with bias voltages between 0 and 90 V.