Lens antenna design for E-band point-to-point radio links

This work presents the development of a millimeter wave lens and a feed antenna array design for the 5G backhaul link application. A 2D beam steering elliptical integrated lens antenna (ILA) is designed, fabricated, and measured. The lens antenna fulfills the regulations for point-to-point link antennas at E-band i.e., 71-76/81-86 GHz for the boresight direction. Based on dielectric properties and commercial availability, Polyethylene (PE) with ε_r = 2.31 and tan δ = 0.0003 is used as the lens material. According to the simulation results the 160 mm diameter lens with an aperture coupled microstrip patch antenna (ACMPA) feed with 8dBi gain gives 38.4 dBi total gain, -16.65-dB sidelobe level, 1.40° HPBW, and scan loss of 1.47 dB for ±5° beam-steering angle at 73.5 GHz. Measurement of the fabricated prototype lens with a WR-10 waveguide gives 38.85 dBi boresight gain, 1.41° HPBW, - 17.75-dB side lobe level, and 2.29 dB scan loss for ±5° beam steering angle. Simulation studies suggest that the feed gain of 13-14 dBi would give the optimum gain performance of an ILA. Therefore, a stacked antenna configuration was studied to improve the gain of an ACMPA. Gain of 11.1 dBi was achieved with the isolated stacked antenna. Maximum of 9.6 dBi broadside gain is obtained with the embedded element within the array configuration. I-shaped resonator structure is used to minimize the mutual coupling between the array elements.