Electronic Industry Articles Update
What is a Directional Coupler?
- tags：

In RF and microwave systems, a directional coupler is an essential passive component that enables signal sampling, monitoring, and routing without disturbing the main transmission line. This article explains what a directional coupler is, how it works, and why it's a critical element in modern wireless communication systems.

What is a Directional Coupler?

A directional coupler is a four-port RF device designed to split or combine signals with controlled coupling in a specific direction. It allows a small portion of the input signal to be "coupled" from the main line to a secondary port, typically for monitoring or testing purposes.

Key Ports in a Directional Coupler:

  • Input Port – Where the main RF signal is fed into the coupler.

  • Output (Through) Port – The main signal continues through this port with minimal insertion loss.

  • Coupled Port – Receives a small fraction of the input signal.

  • Isolated Port – Ideally has no signal in the direction opposite to the coupled port (terminated to prevent reflection).

How Does a Directional Coupler Work?

Directional couplers operate on the principle of electromagnetic coupling between transmission lines. They are designed to couple energy traveling in one direction while isolating energy in the reverse direction. This makes them useful for:

  • Signal monitoring

  • Power measurement

  • Feedback loops

  • System protection

The coupling factor, typically expressed in dB (e.g., 6 dB, 10 dB, 20 dB), determines how much signal is coupled out. A 20 dB directional coupler, for example, will extract 1% of the input power to the coupled port.

Applications of Directional Couplers

Directional couplers are widely used in RF and microwave systems, including:

  • Base stations and DAS systems

  • 5G and LTE networks

  • Satellite communication

  • Test and measurement setups

  • Public safety and military communication

  • RFID and IoT systems

In all these applications, directional couplers enable signal sampling, reflected power detection, and system diagnostics without interrupting the main transmission path.

Types of Directional Couplers

Depending on your application, you may need different types of directional couplers, including:

  • Single-directional couplers

  • Bi-directional couplers

  • Hybrid couplers (90° or 180°)

  • Stripline or waveguide couplers

Choosing the right RF directional coupler depends on factors like frequency range, power handling, coupling level, and physical size.

Why Choose Maniron Electronic as Your Directional Coupler Supplier?

At Maniron Electronic, we’ve specialized in the design and manufacturing of RF passive components since 2002. Our directional couplers are built for performance, low insertion loss, and excellent isolation. Whether you need standard models or custom specifications, we support OEM and ODM projects worldwide.

Our advantages:

  • Wide frequency range support (VHF to 6GHz and beyond)

  • Coupling options: 6 dB, 10 dB, 20 dB, etc.

  • Customizable connectors and enclosures

  • Precision-engineered and factory-tested

Mastering Power Splitter Design From Principle to Engineering Practice
- tags：


In RF and microwave systems, the power splitter is a core passive component responsible for dividing an input signal into multiple outputs with minimal loss and perfect impedance balance.
From cellular base stations to satellite networks and RF test systems, the power splitter ensures signal integrity across transmission paths.

1. Basic Principle of Power Splitters

A power splitter divides an input signal evenly into two or more outputs while maintaining amplitude, phase, and impedance balance.

In ideal conditions, each output receives equal power Pout=Pin/NP_{out} = P_{in}/N, but real-world designs face insertion loss caused by conductor resistance, dielectric losses, and imperfect matching.

Key performance metrics include:

  • Insertion Loss (IL)

  • Isolation between outputs

  • VSWR (impedance matching)

  • Amplitude and phase balance

  • Low PIM (Passive Intermodulation) performance

2. Types of Power Splitters and Structural Features

1. Microstrip Power Splitter

The microstrip power splitter uses printed circuit transmission lines on dielectric substrates. It is lightweight, easy to integrate, and widely used in indoor DAS and small-cell systems.

Features:

  • Compact and low-cost structure

  • Suitable for broadband applications (600–6000 MHz)

  • Easy PCB fabrication and mass production

  • Low PIM achievable with optimized conductor layout and grounding

Applications:
DAS systems, small-cell coverage, RF test platforms.

2. Cavity Power Splitter

The cavity power splitter is a precision-machined metal component that uses resonant cavities and coaxial lines for high-power and high-frequency operation.

Features:

  • Excellent power handling capability

  • Low insertion loss and high isolation

  • Strong mechanical reliability and environmental resistance

  • Ultra-Low PIM performance due to solid metal shielding and fewer junctions

Applications:
Base station feeders, outdoor networks, high-power satellite or radar systems.

3. Stripline Power Splitter

The stripline power splitter employs a symmetrical transmission line structure embedded within a dielectric layer, offering superior phase and amplitude balance across wide frequency ranges.

Features:

  • Excellent amplitude and phase consistency

  • Compact multilayer structure suitable for integration

  • Low return loss and stable impedance characteristics

  • Low PIM through optimized multilayer metallization and bonding process

Applications:
5G MIMO antennas, multi-channel signal distribution, phased-array networks.

3. Key Design Parameters and Optimization

Parameter Definition Target Specification
Insertion Loss Power loss between input and outputs ≤ 0.5 dB
Isolation Signal leakage between outputs ≥ 20 dB
VSWR Impedance matching quality ≤ 1.3
Amplitude Imbalance Power deviation between outputs ≤ 0.3 dB
Phase Imbalance Phase deviation between outputs ≤ 5°
PIM Passive intermodulation ≤ -150 dBc

Design optimization tools: Keysight ADS, Ansys HFSS, CST Microwave Studio — used for tuning line width, dielectric constant, cavity geometry, and connector interfaces.

4. Importance of Low PIM in Splitter Design

In modern 5G networks, low PIM performance directly affects system linearity and data throughput.
Minor imperfections — such as surface oxidation, loose connectors, or uneven contact — can generate intermodulation products, degrading SINR and EVM.

Engineering solutions for Low PIM:

  • High-conductivity plating (silver or gold)

  • Smooth mechanical joints and uniform torque control

  • Fully welded or soldered internal structures

  • PIM-optimized connectors (4.3-10, N-F, DIN-F)

5. Typical Applications of Power Splitters

  1. 5G and 4G Base Stations – Multi-antenna power distribution and feeder networks.

  2. DAS (Distributed Antenna Systems) – Signal splitting for indoor coverage.

  3. Laboratory Testing – Synchronizing multiple RF outputs.

  4. Satellite and Defense Systems – Power balancing in high-frequency payload chains.

6. Future Trends: Toward Integration and Intelligence

As communication systems evolve, power splitter technology continues to advance toward:

  • Ultra-Wideband Design (600–6000 MHz)

  • Integrated Multi-Port Modules

  • High-Power, Low-Loss Cavity Materials

  • Intelligent Power Control through tunable or MEMS-based architectures

keyboard_arrow_up