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