Surface Wave Polarization Converter Using Rotating Unit Cells
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Solution Overview
Problem
Existing artificial impedance surface antennas lack the ability to efficiently convert between transverse magnetic (TM) and transverse electric (TE) polarizations of surface waves, limiting their angular range and flexibility in electromagnetic device designs.
Innovation Solution
A dielectric surface with anisotropic impedance tensor, featuring a two-dimensional array of electrically conductive unit cells with rotating slices, operates above the TE cutoff frequency to convert surface waves between TE and TM modes by electromagnetically coupling the waves through a series of unit cells with gradually changing gap orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If artificial impedance surface antennas use TM-mode operation, then the antenna structure is simple, but the angular range is limited
Solution Approach 1:
The patent changes the operating parameters by switching from TM-mode to TE-mode surface wave operation. This parameter change enables the antenna to radiate efficiently at high angles of elevation, thereby expanding the angular range without fundamentally altering the basic impedance surface structure
Solution Approach 2:
The patent introduces the capability to dynamically switch between TM-mode and TE-mode polarizations. This dynamic operation allows the antenna to adapt its radiation characteristics and angular range based on operational requirements, transforming a static structure into a dynamically versatile system
2Adaptability or versatility
If artificial impedance surface antennas use TE-mode operation, then the angular range and high-angle radiation efficiency are improved, but the ability to convert between polarizations is lost
Solution Approach 1:
The patent creates a universal impedance surface antenna that can perform multiple functions: it can operate in both TM-mode and TE-mode, radiate at various angles, and convert between polarizations. This multi-functionality resolves the contradiction by making the system adaptable to different operational requirements without requiring separate specialized structures
3Adaptability or versatility
If designers integrate antennas onto complex metallic shapes, then the conformal antenna performance is improved, but the polarization switching capability is reduced
Solution Approach 1:
The patent applies local quality by implementing the polarization conversion mechanism at the local level through unit cells with rotating slices. Each unit cell can independently contribute to polarization conversion while the overall structure conforms to complex metallic shapes, allowing both conformal performance and polarization switching to coexist
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
Enables efficient polarization conversion between TE and TM modes, allowing for flexible design changes and improved coupling between antennas or objects, with power conversion efficiency exceeding 90% within the desired frequency range.
Implementation Method 1
converts surface bound electromagnetic waves from one linear combination of modes to a different linear combination by electromagnetically coupling the waves through unit cells with rotating slices
Implementation Method 2
a dielectric surface with anisotropic impedance tensor, featuring a two-dimensional array of electrically conductive unit cells with rotating slices
Data Source
AI summary
A method and apparatus for converting electromagnetic surface waves from TE mode to TM mode or from TM mode to TE mode. The apparatus includes a dielectric surface having an anisotropic impedance tensor which is preferably obtained by a plurality of electrically conductive unit cells disposed on the dielectric surface and arranged in a two dimensional array of unit cells, a majority of the unit cells in said array being divided into at least two portions, with at least one gap separating the at least two portions from each other into two or more patches or plates, the array of unit cells having a surface wave input end and a surface wave output end, gaps in the unit cells disposed closest to the surface wave input end having a first orientation and gaps in said unit cells disposed closest to the surface wave output end having a second orientation different than said first orientation. The electromagnetic surface waves have a frequency greater than a TE cutoff frequency determined by a second solution of Maxwell's equations for said dielectric surface.