3-Way Wilkinson with Improved Isolation | Qucs-S S-parameter Viewer Documentation

Skip to content

# 3-Way Wilkinson with Improved Isolation

## Overview

Enhanced 3-way equal-split power divider with two-stage design providing high isolation between all output ports compared to standard single-stage 3-way Wilkinson.

## Topology

           ┌──────[Z₁, λ/4]────────────[Z₂, λ/4]─────── Port 2
           │                     │                   │
           │                     │                   │
           │                   [R1]                [R2]
           │                     │                   │
    Input──┤                     │                   │
           │                     │                   │
           ├──────[Z₁, λ/4]─────────────[Z₂, λ/4]─────── Port 3
           │                     │                   │
           │                     │                   │
           │                    [R1]                [R2]
           │                     │                   │
           │                     │                   │
           └──────[Z₁, λ/4]─────────────[Z₂, λ/4]─────── Port 4

Structure:

- Stage 1: Three Z₁ branches with R1 isolation resistors

- Stage 2: Three Z₂ branches with R2 isolation resistors

- Two-stage cascade for improved bandwidth and isolation

## Design Equations (Equal Split)

    Z₁ = 2.28 × Z₀    (first stage)
    Z₂ = 1.316 × Z₀   (second stage)

    R₁ = 1.319 × Z₀   (first stage isolation)
    R₂ = 4 × Z₀       (second stage isolation)

For Z₀ = 50 Ω:

Parameter | Value
--- | ---
Z₁ | 114 Ω
Z₂ | 65.8 Ω
R₁ | 66 Ω
R₂ | 200 Ω

All transmission lines: λ/4 at f₀

## References

[1] Goldfarb, M.E. ‘A recombinant, In-phase power divider’, IEEE Trans. Microw. Theory Tech., 1991, 39, (8), pp. 1438–1440 [2] Andrei Grebennikov. “Power combiners, impedance transformers and directional couplers: part II”. High Frequency Electronics. 2008

## See Also

- RF Circuit Synthesis Tools