In this paper, we investigate the beam-squint in the radio frequency (RF) lens of ultra-wideband millimeter-wave (mmWave) systems. We compare, in terms of the beam-squint, the proposed RF lens antenna with the phase shifter-based array in hybrid-beamforming scheme. To reduce the hardware and channel matrix complexities for full digital beamforming, researchers have introduced an RF lens-based hybrid beamforming scheme. The use of mmWave systems, however, causes an increase in bandwidth, which gives rise to beam-squint. Beam-squint can, in the analog beamforming area, misalign beams. We find the causative factors for beam-squint in the RF lens antenna. Based on the beamforming gain at each frequency, we verify that the RF lens is free of the beam-squint effect in a specific situation by analyzing causative factors and assessing throughput. For the analysis, we first numerically interpret the beam-squint of each antenna type using 3D electromagnetic analysis software. Based on the results, we present the degraded spectral efficiency by system-level simulations with 3D indoor ray tracing. Finally, to verify our analysis, we fabricate an actual RF lens antenna and demonstrate the real performance using an mmWave, NI PXIe, software-defined radio system.

No abstract

No abstract

In this article, we discuss the potential of radio frequency (RF) lens for ultra-wideband millimeter-wave (mmWave) systems. In terms of the beam squint, we compare the proposed RF lens antenna with the phase shifter-based array for hybrid beamforming. To reduce the complexities for fully digital beamforming, researchers have come up with RF lens-based hybrid beamforming. The use of mmWave systems, however, causes an increase in bandwidth, which gives rise to the beam squint phenomenon. We first find the causative factors for beam squint in the dielectric RF lens antenna. Based on the beamforming gain at each frequency, we verify that, in a specific situation, RF lens can be free of the beam squint effect. We use 3D electromagnetic analysis software to numerically interpret the beam squint of each antenna type. Based on the results, we present the degraded spectral efficiency by system-level simulations with 3D indoor ray tracing. Finally, to verify our analysis, we fabricate an actual RF lens antenna and demonstrate the real performance using a mmWave, NI PXIe, software-defined radio system.