Reciprocal Circular Polarization Selective Surface with Endwise Coupling
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Solution Overview
Problem
Existing circular polarization selective surfaces (CPSS) suffer from performance degradation at oblique incidence and are bulky due to their design, which limits their effectiveness in applications requiring broader angular coverage and compact form factors.
Innovation Solution
A CPSS design incorporating endwise electromagnetic coupling between transverse segments of crankwires, integrated within a dielectric substrate, forming a 2D array with 2-fold rotational symmetry, which enhances performance by providing both longitudinal and transverse electromagnetic coupling, improving selectivity and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional CPSS design with 2D periodic array of crankwires is used, then circular polarization selectivity is achieved, but performance degrades at oblique incidence
Solution Approach 1:
The patent introduces longitudinal reflection asymmetry by positioning transverse segments at different longitudinal locations within the substrate thickness. The first transverse segment is positioned closer to the first face while the second transverse segment is positioned closer to the second face, creating an asymmetric structure that maintains consistent polarization selectivity for waves incident from either face, thereby improving oblique incidence performance
Solution Approach 2:
The patent transitions from a conventional 2D periodic array to a 3D structure by distributing transverse segments at different longitudinal positions within the substrate. This three-dimensional arrangement with controlled spacing creates multiple coupling paths that maintain performance across a broader range of incidence angles
2Reliability
If a conventional CPSS design with separate longitudinal and transverse segments is used, then electromagnetic coupling is achieved, but the structure becomes bulky
Solution Approach 1:
The patent merges the longitudinal and transverse segments into an integrated crankwire structure where the longitudinal segment electrically connects the two transverse segments. This unified structure provides both longitudinal and transverse electromagnetic coupling within a compact form factor, eliminating the need for separate coupled components and reducing overall device volume
Solution Approach 2:
The patent embeds the crankwire structure within the dielectric substrate, nesting the conductive elements inside the substrate volume rather than arranging them in a bulky external configuration. The transverse segments are positioned at different longitudinal locations within the substrate thickness, creating a space-efficient nested arrangement that maintains coupling functionality while minimizing physical dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed CPSS design maintains high selectivity and efficiency across a range of incidence angles, including oblique incidence, while reducing the physical size and weight, thereby addressing the limitations of prior art in terms of performance and form factor.
Implementation Method 1
endwise electromagnetic coupling between transverse segments of crankwires
Implementation Method 2
circular polarization selective surfaces that predominately reflects one sense, or handedness, of a circular polarization (CP) of an incident electro-magnetic (EM) wave
Data Source
AI summary
The invention provides a reciprocal circular polarization selective surface (CPSS) formed of two mutually orthogonal arrays of linear dipoles disposed at opposite transverse CPSS faces, with opposing orthogonal dipoles individually connected by transmission lines, wherein adjacent dipoles are endwise coupled for enhancing CPSS performance. In one implementation, the CPSS comprises a two-dimensional array of cells with each cell composed of two separate crankwires positioned at two diagonally opposite corners of the cell so that the cell has a 2-fold rotational symmetry and endwise coupling of adjacent crankwires for enhanced performance at normal and oblique angles of incidence.