Compact Multibeam Antenna Using Dielectric Superstrate

The patent transitions from a planar arrangement of antenna elements to a three-dimensional configuration by introducing a superstrate layer above the substrate. Antenna elements are distributed across multiple layers (substrate and superstrate) at different heights, enabling beam formation in three dimensions rather than just on a two-dimensional plane. This vertical dimensionality allows compact multibeam operation with reduced horizontal footprint.

The patent implements a nested structure where antenna elements are arranged in concentric rings that are stacked vertically across multiple layers. The rings are positioned at different heights (z-coordinates) and radial distances, creating a nested configuration where smaller rings are positioned both radially and vertically within the structure of larger rings. This nesting enables multiple beams to be formed from a compact, space-efficient geometry.

The patent introduces a superstrate layer with specific dielectric properties as an intermediary between the antenna elements on the substrate and the free space. This superstrate acts as a mediator that controls the electromagnetic field distribution, reducing mutual coupling between closely spaced elements while maintaining their radiation efficiency. The dielectric properties of the superstrate are optimized to achieve the desired coupling reduction.

The patent assigns different dielectric constants to different layers: the substrate has dielectric constant εr1 and the superstrate has dielectric constant εr2 where εr2 > εr1. This local variation in dielectric quality allows optimization of the electromagnetic environment in different regions. The higher permittivity superstrate concentrates the electric field in regions where it is needed while reducing field overlap between adjacent elements, thereby reducing coupling.

The patent designs a universal antenna element structure that can serve multiple beam directions simultaneously. The same basic element geometry and feeding mechanism are used across all rings and layers, with beam direction controlled by the position and phase of individual elements rather than requiring different element types. This universality simplifies manufacturing while enabling formation of multiple beams through signal processing.

The patent divides the antenna structure into segmented concentric rings, where each ring can be independently fed and controlled. This segmentation allows the complex multibeam function to be broken down into simpler, identical repeating units (rings with elements). Each ring segment follows the same design pattern, simplifying manufacturing and assembly while the collective arrangement of segmented rings produces the desired multibeam radiation pattern.