Subwavelength Waveguide Resonators for Compact Millimeter-Wave Filters
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Solution Overview
Problem
Conventional microwave waveguide components are bulky and heavy, limiting their application in small satellite systems and other high-power applications due to wavelength scaling, and existing metamaterial filters are not compatible with waveguide technology.
Innovation Solution
The use of subwavelength resonant metallic elements, such as pins, within a cut-off cavity or waveguide, utilizing locally resonant metamaterials to create compact, tunable, and reconfigurable microwave filters, diplexers, and multiplexers, compatible with coaxial and rectangular antenna feeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar or cylindrical resonators are used, then manufacturing is simpler, but quality factor is insufficient for millimeter wave applications
Solution Approach 1:
The resonator is divided into multiple resonant sections along its length, each contributing to the overall resonant characteristics. This segmentation allows the resonator to achieve higher quality factors by creating multiple resonant modes that can be optimized independently, directly addressing the insufficient quality factor issue in millimeter wave applications.
Solution Approach 2:
The invention transitions from conventional planar (2D) or simple cylindrical (1D) resonators to a three-dimensional spherical resonator structure. This dimensional change enables exploitation of radial and angular resonant modes, significantly increasing the quality factor by providing additional degrees of freedom for resonant energy storage.
2Adaptability or versatility
If conventional resonators are used, then device complexity is lower, but frequency tuning range is limited
Solution Approach 1:
The resonator incorporates variable capacitive elements that can be dynamically adjusted to change the resonant frequency. This dynamic tuning capability allows the resonator to operate across a wide frequency range while maintaining high quality factor, enabling frequency agile millimeter wave applications without requiring multiple fixed-frequency resonators.
Solution Approach 2:
The invention changes key electrical parameters of the resonator, specifically the capacitance values, to achieve frequency tuning. By varying the capacitive loading on the spherical resonator, the resonant frequency can be adjusted across a broad range while preserving the high quality factor characteristics enabled by the spherical geometry.
3Loss of energy
If high quality factor resonators are designed, then signal loss is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The spherical resonator design concentrates the electromagnetic energy distribution in specific regions of the sphere, creating local quality enhancements. This localized energy concentration allows the resonator to achieve high quality factors even with moderate manufacturing tolerances, as the critical field regions are optimized for maximum energy storage while less critical regions can accommodate manufacturing variations.
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 miniaturized, lightweight, and customizable microwave components with adjustable bandwidth and low dispersion, suitable for high-power applications like satellite communications and radar systems, while reducing crosstalk and insertion loss.
Implementation Method 1
a resonant frequency of the spherical resonator may be determined by a radius of the spherical resonator and a speed of light in free space
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 1F
AI summary
A passive device comprising a hollow waveguide including first and second wall structures extending in a guiding direction, an interconnecting base extending between the wall structures and an enclosure extending between the wall structures, the enclosure being located opposite the interconnecting base; and at least one array of coupled resonant structures enclosed inside the waveguide, the array being configured to provide coupled local resonators and a microwave or millimeter wave frequency passband for providing at least one selected microwave or millimeter wave signal, the array extending along the guiding direction and being located between the wall structures. Each resonant structure extends from the interconnecting base into the hollow waveguide to define a microwave or millimeter wave subwavelength resonant structure, and successive resonant structures are separated by a microwave or millimeter wave subwavelength distance. A resonance frequency of the resonant structures is less than a cut-off frequency of the waveguide.