A Metasurface-Enabled Lens Antenna Demonstrating Electromechanical Beam-Tilting for 5G Applications

In this paper, a probe-fed, transmissive metasurface lens-based antenna system in the sub-6 GHz frequency range for possible fifth-generation (5G) applications is proposed. The design facilitates for gain enhancement and phase shifter less beam tilting architecture. The structure consists of a probe-fed compact patch antenna, printed on FR4 substrate. The antenna resonates at 5.8 GHz with the −10 dB impedance bandwidth of 210 MHz extending from 5.68 till 5.89 GHz. The maximum realized gain at resonance is 2.6 dBi. The double-sided metasurface, printed on Rogers RT-Duroid 5880 substrate, is placed on top of the antenna with an air gap of 24.5 mm. This arrangement exhibits a maximum transmission gain of 7.98 dBi at resonance, with a gain enhancement of 5.38 dB in conjunction to a impedance bandwidth of 150 MHz from 5.72 - 5.87 GHz. The metasurface is polarization independent. The proposed antenna structure has been simulated for different incidence angles by rotating the metasurface around the antenna by 10° and 20°, with the resulting transmitted beam also rotating by the respective angles, thus demonstrating the beam-tilting capability of the system. This beam-tilting is achieved by only mechanically rotating the metasurface. The design has been fabricated and measured, with the experimental results matching with simulated data, with only a variation of less than 1 dB in the gain values and a shift of 50 MHz in the resonance frequency. This is attributed to variation in precise adjustment of the air-gap. The design is scalable and the process of validating the design in Frequency Range (FR2) band (24.25 - 52.6 GHz) is in progress. The proposed antenna-metasurface system is lightweight and low-cost alternative to 5G sub-6 GHz frequency band applications.