Resonator With Interdigitated Posts For Miniaturization

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Solution Overview

Problem

Current resonators for telecommunications face challenges in miniaturization while maintaining high Q factors and power-handling capabilities, with traditional cavity resonators being too large and ceramic mono-block filters having low Q factors, leading to limitations in both size and performance for small-cell applications.

Innovation Solution

The design employs a split resonator structure with interdigitated pairs of resonant posts arranged in arrays for strong magnetic field coupling, allowing for reduced size and increased frequency agility, along with adjustable intra- and inter-pair gaps for optimized coupling, enabling high Q factors and miniaturization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional cavity resonators are used, then high Q factor is achieved, but the physical size becomes too large for small-cell applications

Engineering Contradiction:
ImproveQ factorVSAvoidphysical size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The resonator is divided into multiple discrete resonant posts (typically 4 posts arranged in pairs) rather than using a continuous cavity structure. Each post acts as an independent resonant element, and the collective interaction between posts achieves the desired filtering function with reduced volume.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The resonant posts are arranged in a three-dimensional configuration within a reduced-volume cavity, utilizing vertical and horizontal spacing to achieve magnetic coupling. The posts extend in opposite directions from top and bottom walls, creating a compact 3D structure that maintains high Q while minimizing footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If lumped elements are used for miniaturization, then size is reduced, but Q factor drops to 60-100 which is insufficient for high-performance applications

Engineering Contradiction:
ImprovesizeVSAvoidQ factor
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The design changes the resonant element from conventional lumped capacitors/inductors to distributed resonant posts with specific geometric parameters (length, diameter, spacing). By optimizing the physical dimensions and magnetic coupling between posts, the system achieves Q factors in the hundreds or thousands while maintaining compact size.

Inventive Principle:
Principle #35Parameter changes

3Power

If cavity filters are used for high-power applications, then power-handling capability is sufficient, but the size is relatively large limiting widespread use

Engineering Contradiction:
Improvepower-handling capabilityVSAvoidsize
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

The design merges the advantages of cavity filters (high power handling, high Q) with the compactness of distributed elements. By using multiple resonant posts with magnetic coupling within a reduced-volume cavity, the filter achieves both high-power capability and small size suitable for small-cell deployments.

Inventive Principle:
Principle #5Merging (Combining)

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

This approach achieves significant size reduction and improved performance by enabling strong, controllable coupling between resonator pairs, resulting in higher Q factors and reduced physical dimensions, suitable for small-cell applications without sacrificing power-handling capabilities.

Implementation Method 1

one of the first and second resonant posts of one pair of resonant posts is separated by the inter-pair gap and located in proximity with another of the first and second resonant posts of another pair of resonant posts for magnetic field coupling between the one of the first and second resonant posts of one pair of resonant posts and the another of the first and second resonant posts of the another pair of resonant posts

Methodology Applied
Scientific EffectMagnetic field coupling: Magnetic Field

Data Source

PatentEP3285331B1resonator
Publication Date: 2020.07.22 NOKIA TECHNOLOGIES OY
  • EP3285331B1 patent drawingFigure 1~2
  • EP3285331B1 patent drawingFigure 3
  • EP3285331B1 patent drawingFigure 4

AI summary

A resonator and method are disclosed. The resonator comprises: a resonant chamber defined by a first wall, a second wall opposing the first wall and side walls extending between the first wall and the second wall; pairs of resonant posts, each pair of resonant posts comprising a first resonant post separated from a second resonant post by an intra-pair gap and located in proximity with each other for magnetic field coupling between the first resonant post and the second resonant post, the first resonant post being grounded on the first wall and extending into the resonant chamber from the first wall, the second resonant post being grounded on the second wall and extending into the resonant chamber from the second wall; and wherein the pairs of resonant posts are separated by an inter-pair gap and located in proximity with each other for magnetic field coupling between the pairs of resonant posts. In this way, coupling is provided not only between the resonant posts making up each pair, but also between pairs of resonant posts which provides for an even greater level of miniaturisation compared to previous approaches, while still retaining the same degree of performance.