INDUSTRY COMPONENT

Coupled Line

A coupled line is a transmission line structure used in directional couplers to sample a portion of signal power from a main transmission line with minimal interference.

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Component Specifications

Definition
A coupled line consists of two or more parallel transmission lines placed in close proximity, enabling electromagnetic coupling between them. In directional couplers, this configuration allows a fraction of the signal power traveling along the main line to be transferred to a secondary coupled line, facilitating signal monitoring, measurement, or power splitting while maintaining signal integrity and directionality.
Working Principle
Operates based on electromagnetic coupling between adjacent transmission lines. When a signal propagates along the main line, a portion of its electromagnetic field interacts with the coupled line, inducing a proportional signal in the coupled port. The coupling factor depends on the physical dimensions, spacing, and dielectric properties, with directionality achieved through specific geometric arrangements that favor forward or backward wave coupling.
Materials
Typically made from conductive materials like copper or aluminum for the traces, with substrates of PTFE (Teflon), FR4, ceramic, or other low-loss dielectrics. May include plating with gold or silver for enhanced conductivity and corrosion resistance in high-frequency applications.
Technical Parameters
  • VSWR <1.5:1
  • Impedance 50 ohms or 75 ohms
  • Directivity >20 dB
  • Insertion Loss <0.5 dB
  • Coupling Factor 3 dB to 30 dB
  • Frequency Range DC to 40 GHz
Standards
ISO 9001, IEC 61169, MIL-PRF-39012

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Coupled Line.

coupled line directional coupler RF component microwave engineering signal coupling transmission line electromagnetic coupling power divider network analyzer Coupled Line in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

Directional Couplers

Passive microwave/RF components that sample a portion of signal power from a transmission line in a specific direction while maintaining isolation from signals traveling in the opposite direction.

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Engineering Analysis

Risks & Mitigation
  • Impedance mismatch leading to signal reflections
  • Poor directivity causing measurement inaccuracies
  • Material degradation at high frequencies or temperatures
  • Manufacturing tolerances affecting performance consistency
FMEA Triads
Trigger: Insufficient spacing between lines
Failure: Excessive coupling or signal leakage
Mitigation: Implement precise design rules and quality control during fabrication to maintain specified dimensions.
Trigger: Substrate material imperfections
Failure: Increased insertion loss or frequency drift
Mitigation: Use certified low-loss dielectric materials and conduct regular material testing.
Trigger: Environmental exposure to moisture or contaminants
Failure: Corrosion or electrical shorting
Mitigation: Apply protective coatings or encapsulation and ensure proper storage and handling.

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±0.1 mm for line width and spacing, ±5% for electrical parameters like coupling factor
Test Method
Vector network analyzer (VNA) measurements for S-parameters, including insertion loss, return loss, and directivity, per industry standards like IEC 61169.

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the primary function of a coupled line in a directional coupler?

To sample a controlled portion of signal power from the main transmission line without significantly disrupting the signal flow, enabling applications like power monitoring, measurement, and signal splitting.

How does a coupled line achieve directionality?

Through specific geometric designs, such as asymmetric spacing or multi-line configurations, that preferentially couple signals traveling in one direction (e.g., forward) while minimizing coupling in the opposite direction, enhancing isolation and performance.

What factors affect the coupling factor of a coupled line?

The coupling factor is influenced by the physical proximity of the lines, their length, the dielectric constant of the substrate, and the operating frequency, with tighter spacing and longer lines generally increasing coupling.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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