Wilkinson Power Dividers/Combiners: Advantages and Disadvantages

This page explores the advantages and disadvantages of Wilkinson power dividers/splitters and combiners. It outlines the benefits and drawbacks associated with using this specific design in RF and microwave applications.

What is a Wilkinson Power Divider/Combiner?

Introduction: Power dividers and combiners are essential components in many RF and microwave systems. Power combiners do exactly as their name suggests: they combine the power from multiple input ports into a single output port. Conversely, power dividers split the input power equally (or unequally, depending on the design) across multiple output ports.

There are several ways to design these power combiners and splitters. One popular method involves the Wilkinson design, as shown in Figure 1. This particular example demonstrates a 2-way Wilkinson power splitter.

A key advantage of the Wilkinson design is that it can be matched at all ports and exhibits lossless behavior when the output ports are matched.

Generally, power dividers and combiners can be categorized into three primary designs:

• Resistive design
• Reactive design
• Wilkinson design

Benefits or Advantages of Wilkinson Power Dividers/Combiners

Here are the key advantages of using a Wilkinson power divider/combiner:

• Robust Design: It is considered one of the most robust power divider/combiner designs available.
• Matched Output Ports: Due to its inherent design, it presents matched output ports, minimizing reflections.
• Better Isolation: Wilkinson dividers provide superior isolation between output ports compared to simpler T-junction splitters.
• Low Insertion Loss: They offer relatively low signal loss during power division or combination.
• Wideband Operation: Wilkinson dividers are suitable for wideband applications, often operating over bandwidths of 2:1 or greater.
• Arbitrary Power Division: The design can be tailored to achieve unequal (arbitrary) power division between the output ports.
• Isolation via Resistors: Isolation between ports is effectively achieved through the use of terminating resistors. These resistors attenuate any unequal mismatch or out-of-phase conditions that might couple power from one line to another.

Drawbacks or Disadvantages of Wilkinson Power Dividers/Combiners

While offering numerous advantages, Wilkinson power dividers/combiners also have some drawbacks:

• Limited Power Handling: The power handling capability is limited because the terminating resistors must be physically mounted within the coupler, divider, or combiner. These resistors have a power dissipation limit.
• Higher Insertion Loss Compared to Reactive Designs: The insertion loss of a Wilkinson design is generally higher than that of a reactive design.
• Microstrip or Stripline Implementation: These dividers/combiners are often implemented using microstrip or stripline techniques.