Magnetically Coupled Antenna Matching Circuit for Multi-Band Impedance

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Solution Overview

Problem

Existing antenna devices struggle to establish impedance matching between the feed circuit and the radiating element across multiple frequency ranges due to the frequency-dependent impedance changes of a single inductor, making it difficult to maintain optimal matching in a wide frequency spectrum.

Innovation Solution

An antenna device incorporating an electronic component with a first coil connected in series, a second coil coupled by magnetic field coupling, and a capacitor in parallel to the second coil, which stabilizes impedance matching across various frequencies by adjusting inductance characteristics through magnetic field coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single inductor is connected between the feed circuit and the radiating element to establish impedance matching, then the impedance matching can be established at a specific frequency, but the impedance matching cannot be maintained across multiple frequency ranges due to frequency-dependent impedance changes

Engineering Contradiction:

Improveimpedance matching capability across frequency rangesVSAvoidimpedance matching stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The single inductor is segmented into multiple inductors with different impedance characteristics. Each inductor is designed to provide optimal impedance matching at specific frequency ranges, allowing the antenna device to maintain reliable impedance matching across multiple frequency ranges simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inductor configuration is designed to perform multiple functions: it provides impedance matching at multiple frequency ranges while also enabling the antenna to operate effectively across a broad frequency spectrum. The combined inductor structure serves as both a matching network and a multi-band operating enabler

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If an autotransformer with an LC closed circuit is used to establish impedance matching in a wide frequency range, then the impedance matching is improved, but an attenuation pole is introduced that prevents matching around the resonant frequency

Engineering Contradiction:

Improveimpedance matching bandwidthVSAvoidimpedance matching continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The problematic LC closed circuit that creates the attenuation pole is extracted and replaced with an open-circuit configuration. This removes the resonant frequency constraint while preserving the impedance matching capability across wide frequency ranges, eliminating the matching gap around the resonant frequency

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a closed LC circuit that creates resonance and attenuation, the invention inverts the approach by using an open-circuit configuration with capacitors connected to the inductors. This inverted structure avoids the attenuation pole problem while achieving wideband impedance matching

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration enables effective impedance matching between the feed circuit and radiating element in multiple frequency ranges, enhancing performance and reducing impedance variations, particularly at both low and high frequencies.

Implementation Method 1

a second coil coupled to the first coil by magnetic field coupling

Methodology Applied

Scientific EffectMagnetic field coupling: Electromagnetic Induction

Implementation Method 2

a first capacitor electrically connected in parallel to the second coil

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS20260018791A1Antenna device, electronic component and associated methods

Publication Date: 2026.01.15 MURATA MFG CO LTD

AI summary

An antenna device and an electronic component that establish matching between the impedance of a feed circuit and the impedance of a radiating element in a plurality of frequency ranges are provided. An antenna device includes a feed circuit, a radiating element connected to the feed circuit, and an electronic component between the feed circuit and the radiating element. The electronic component establishes impedance matching between the feed circuit and the radiating element. The electronic component includes a first terminal, a second terminal, a first coil connected in series between the first terminal and the second terminal, a second coil coupled to the coil by magnetic field coupling, and a first capacitor electrically connected in parallel to the coil.