Directional Coupler Filtered Termination for Multi-Band Directivity

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Solution Overview

Problem

Existing directional couplers face challenges in maintaining directivity when handling RF signals in multiple frequency bands simultaneously, as the termination condition cannot be adjusted effectively for individual frequency bands, leading to potential degradation in directivity.

Innovation Solution

A directional coupler design that includes a main line, a sub-line, filter circuits, and termination circuits, where the filter circuits allow specific frequency signals to pass through while attenuating others, enabling the impedance values of the termination circuits to be set properly for each frequency band without the need for switch activation, thereby improving directivity across multiple frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single termination circuit is used for multiple frequency bands, then device complexity is reduced, but directivity degrades when multiple frequency band signals are processed simultaneously

Engineering Contradiction:

Improvetermination circuit configurationVSAvoiddirectivity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The single termination circuit is segmented into multiple frequency-specific termination circuits (first termination circuit for first frequency band, second termination circuit for second frequency band). Each termination circuit is dedicated to a specific frequency band, allowing independent optimization of termination conditions for each band, thereby maintaining high directivity across multiple frequency bands without requiring complex switching mechanisms.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each termination circuit is designed with local quality optimized for its specific frequency band. The first termination circuit has termination conditions specifically tailored for the first frequency band, while the second termination circuit has termination conditions optimized for the second frequency band. This local optimization ensures that each frequency band receives the most appropriate termination, improving overall system reliability and directivity.

Inventive Principle:

Principle #3Local quality

2Reliability

If switches are used to switch termination conditions for different frequency bands, then directivity can be maintained, but device complexity and manufacturing cost increase

Engineering Contradiction:

ImprovedirectivityVSAvoidswitching mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Filter circuits are introduced as intermediary elements between the main line and the respective termination circuits. The filter circuits automatically route signals based on their frequency characteristics, allowing the first frequency band signal to reach the first termination circuit and the second frequency band signal to reach the second termination circuit without requiring active switching mechanisms. This passive frequency-based routing simplifies the overall device structure while maintaining high directivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system utilizes the inherent frequency characteristics of signals to automatically direct them to the appropriate termination circuit through the filter circuits. Each frequency band signal self-routes to its designated termination circuit based on frequency matching, eliminating the need for external control signals or active switching components. This self-service mechanism reduces device complexity and manufacturing costs while maintaining reliable directivity performance.

Inventive Principle:

Principle #25Self-service

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 design enhances directivity and isolation for signals in multiple frequency bands, reducing manufacturing costs by eliminating the need for active elements like switches, and allows for efficient signal distribution and termination based on frequency characteristics.

Implementation Method 1

a first filter circuit disposed between the fourth port and the first termination circuit, wherein the first filter circuit has frequency characteristics allowing the first coupled signal to pass therethrough and attenuating the second coupled signal

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 2

a sub-line coupled to the main line, and a termination portion including a plurality of elements and disposed at one port of the sub-line

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Data Source

PatentUS10916824B2Directional coupler and communication unit

Publication Date: 2021.02.09 MURATA MFG CO LTD

AI summary

A directional coupler includes a main line through which a first signal in a first frequency band and a second signal in a second frequency band pass from a first port to a second port, a sub-line electromagnetically coupled to the main line and having a third port and a fourth port, the third port outputting a first coupled signal corresponding to the first signal and a second coupled signal corresponding to the second signal, a first termination circuit connected to the fourth port and used in outputting the first coupled signal, a second termination circuit connected to the fourth port and used in outputting the second coupled signal, and a first filter circuit disposed between the fourth port and the first termination circuit, wherein the first filter circuit has frequency characteristics allowing the first coupled signal to pass therethrough and attenuating the second coupled signal.