Linear-Polarized and Dual-Polarized Electric-field Sensor using LiNbO3 Phase Modulator for 28 GHz Band

We have developed an antenna-coupled-electrode electric-field sensor for 28 GHz-band in 5th generation mobile communication as a receiving antenna [1] . In this paper, we report a 3D near field receiving pattern for the simultaneously-receiving dual-polarized type electric-field sensor and a linear-polarized type electric-field sensor that have 2 and 2by 2 array antennas respectively. The electric-field sensor is fabricated on a z-cut LiNbO3 film of about 50 μm thickness that is stacked on a base substrate of SiO 2 glass about 250 μm thickness. Two square patch antennas as a receiving antenna are connected to a standing-wave resonant electrode by using microstrip feeding lines to form an antenna-coupled electrode on the electric-field sensor. An optical waveguide as a phase modulator is fabricated on the reverse side of the LiNbO3 film. Figure 1 schematically shows a linear-polarized type electric-field sensor, and a dual-polarize type electric-field sensor. For evaluating the receiving pattern for the electric-field sensor, we carried out the near field E θ and E ϕ receiving-pattern measurements using a WR-28 standard horn antenna as a transmitting antenna. Figure 2 shows a 3D (spherical coordinate) receiving-pattern measurement setup using an arm vertical articulated robot and optical fiber link system as a microwave transmitting system. In the case of a dual-polarized electric field sensor, we can simultaneously measure orthogonally polarized electric fields using a 2-port vector network analyzer with an option. Figure 3 show measured receiving patterns for the linear-polarized type electric-field sensor at 28.1 GHz. Figure 4 shows measured receiving pattern for the dual-polarized type electric-field sensor at 28.1 GHz. These results show the fact that the-dual polarize electric field sensors can measure electric fields simultaneously. However, the peak zenith angle for the dual-polarize electric field sensor is about 15 degrees tilted. We are developing the simultaneously-measured orthogonally-polarized electric field sensor with the peak zenith angle at 0 degree.