A Millimeter-Wave Beam-Steering Lens Antenna With Reconfigurable Aperture Using Liquid Crystal

For the first time, a liquid crystal (LC) filled lens antenna is investigated for beam steering in this paper. The LC's anisotropy is applied inside a semicircular shaped parallel-plate waveguide to achieve a deflection of the propagating electromagnetic wave at the interface of lower and higher permittivities. Using an electrode network, the direction of the sector of higher permittivity can be adjusted and, therefore, so can the beam direction. The main advantage of this antenna concept is that neither phase shifters nor switching networks are needed, resulting in a very simple approach for beam steering. Operating at V-band, from 50 to 75 GHz, the first demonstrator proves the antenna concept by reconfiguring the beam in predefined directions of -30°, 0°, and +30° to simplify the electrode biasing network. Furthermore, it is feasible and being demonstrated to adjust the beamwidth and to generate multiple beams. In the measurements, the antenna exhibits a measured input reflection below -10 dB over the complete frequency range. For the unsteered radiation pattern, the sidelobe level is between -8 and -12 dB, whereas these values degrade to -4.5 to -6 dB for the steered radiation pattern at ±30°. The measured gain is between 13 and 15 dBi.