Optimization of Three-Dimensional Multi-Shell Dielectric Lens Antennas to Radiate Multiple Shaped Beams for Cellular Radio Coverage

Abstract

In this paper, a multi-shell spherical dielectric lens antenna is synthesized to radiate multibeams with optimum shaped patterns for radio coverage at millimeter wave (mmW) frequencies. In particular, the design considers the composing characteristics of discrete multi-shell Luneburg lens antenna as an initial structure, and synthesizes its permittivity and sizes of dielectric shells to produce relatively shaped main beam patterns rather than conventional pencil-shapes. It targets to minimize inter-beam overlapping transition regions with slowly varying power density in the coverage boundary, and therefore reduce the ping-pong effect of inter-sector handovers to potentially minimize the inter-cell interferences arising from the over-large gain of pencil beam when the user equipment (UE) is at near the sector boundary far-off the beam peak. After the synthesis, the antenna is implemented at 38 GHz with both numerical simulation and measurement results shown to validate the concept. Successfully validation on the feasibility of beam synthesis in comparison to that of Luneburg lens antennas has been achieved. Discrepancy in fabrication to potentially result in slight radiation degradation is also discussed.INDEX TERMS Genetic algorithm, Luneburg lens antenna, multi-beam radiation, pattern synthesis.

Modeling the Performance Impact of Cubic Macro Cells Used in Additively Manufactured Luneburg Lenses

“…The core and surrounding shells are homogeneous, with their respective permittivity and radius chosen to mimic a continuously graded LL. The optimum selection of these parameters proceeds once the number of layers is chosen and includes both closed form expressions [12] and iterative methods [13][14][15]. The equations of [12] are repeated here as a point of reference.…”

“…Fig. 12 provides insight into why N = 6 is a good choice for a layered LL that is designed using ( 14) and (15). By substituting x for r/r l in (13) and integrating with respect to x, we derive the area under the continuous LL curve:…”

Experimental evaluation of Luneburg lens using radial holes for relative permittivity distribution

“…For a simpler configuration, a Luneburg lens [5] can be used to form a high-gain beam. Some configurations of the Luneburg lens antenna have been studied, such as a two-layered spherical configuration using radial holes with a single depth fabricated in perpendicular directions to the sphere [7], a plate configuration with holes [8], a spherical configuration with radial tapered holes [9], an air-filled parallel-plate waveguide [10], a multi-shell configuration [11], one using discrete polymer cubes [12], and one using a metasurface structure [13]. Furthermore, we previously studied the Luneburg lens used for a beamforming network with input and output ports [6].…”

Dielectric Gratings Enhancing the Field of View in Low Dielectric Permittivity Elliptical Lenses

“…The planar configuration facilitates considerably the active front-end integration w.r.t. to other wide angle steering concepts with curved focal surfaces [3]- [5]. The high 𝜂 𝑎𝑝 enables the realization of compact Fly's eye lens arrays.…”