Split-Ring Antenna Case Structure for Low-Height Resonance

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Solution Overview

Problem

Existing antenna devices face challenges in achieving reduced height while maintaining structural strength and design flexibility, particularly when accommodating antenna elements that radiate radio waves with specific frequencies.

Innovation Solution

The antenna device incorporates a case with a predetermined opening that functions as an LC resonator, comprising main openings and a coupling opening, allowing it to resonate with various frequencies without altering its height, thereby reducing the case's overall dimensions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the case height is increased to accommodate a high opening for resonance, then the resonance function is improved, but the compactness and design flexibility are worsened

Engineering Contradiction:
Improveresonance functionVSAvoidcase height
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent transitions from a vertical resonance structure (requiring height) to a horizontal resonance structure using a slot antenna on the side plate. The resonance path is reconfigured to extend horizontally across the case width rather than vertically through the case height, allowing resonance functionality to be achieved in a different spatial dimension that does not compromise case compactness

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

Solution Approach 2:

Instead of making the case taller to accommodate vertical resonance, the patent inverts the approach by implementing horizontal resonance through a slot opening on the side plate. The resonance direction is reversed from vertical to horizontal, enabling the case to maintain its compact height while still achieving the required resonance function

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If the opening height is increased to achieve resonance at specific frequencies, then the resonance performance is improved, but the structural strength is worsened

Engineering Contradiction:
Improveresonance performanceVSAvoidcase strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by creating a specific slot opening with precise dimensions (extending from the upper plate toward the lower plate but not necessarily through it) on the side plate. This localized opening is optimized for resonance while the rest of the case structure remains intact and strong. The slot's position and size are carefully controlled to achieve resonance performance without compromising overall structural integrity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The side plate with the slot opening acts as a flexible resonating structure. The slot creates a controlled weakness that allows the side plate to resonate at the required frequency while the overall case structure maintains its strength. The thin film-like side plate with the slot serves dual purposes: structural integrity and resonance functionality

Inventive Principle:
Principle #30Flexible shells and thin films

3Volume of moving object

If the case is made taller to accommodate the antenna element and circuit board, then the accommodation space is improved, but the compactness is worsened

Engineering Contradiction:
Improveaccommodation spaceVSAvoidcase height
Core Design Contradiction:
Volume of moving objectVSLength of moving object

Solution Approach 1:

The patent reconfigures the resonance path from a vertical dimension (requiring height) to a horizontal dimension (using case width). This allows the case to maintain a compact height suitable for accommodating components while achieving resonance through horizontal current paths in the side plate, effectively decoupling resonance requirements from height requirements

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

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 LC resonator structure enables the antenna device to radiate radio waves with desired frequencies while maintaining a compact form factor, balancing strength and design flexibility.

Implementation Method 1

The slot 94 has a length corresponding to a predetermined frequency which is a frequency of a radio wave radiated from the antenna element 98. Specifically, the length of the slot 94 is designed to be about half a wavelength of the radio wave which has the predetermined frequency. The thus-formed slot 94 resonates with the radio wave radiated from the antenna element 98

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP4478544B1Antenna device
Publication Date: 2025.12.17 JAPAN AVIATION ELECTRONICS IND LTD
  • EP4478544B1 patent drawingFigure 1~2
  • EP4478544B1 patent drawingFigure 3~4
  • EP4478544B1 patent drawingFigure 5~6

AI summary

An antenna device comprises a case and an antenna element. The antenna element is arranged in the case and radiates a radio wave with a predetermined frequency which has a plane of polarization in parallel to a predetermined plane. The case is formed with a predetermined opening. The predetermined opening has two main openings and a coupling opening. The two main openings are apart from each other in a first direction perpendicular to the predetermined plane. The coupling opening couples the two main openings together in the first direction. The coupling opening has a size smaller than another size of each of the two main openings in a second direction perpendicular to the first direction. The predetermined opening forms a split ring resonator which resonates at the predetermined frequency and radiates a radio wave corresponding to the radio wave radiated from the antenna element.