LC BALUN Calculator

A BALUN (BALanced-UNbalanced) converts between a balanced transmission line (equal and opposite signals) and an unbalanced one (coaxial, single-ended). LC BALUNs achieve this with reactive networks at a single frequency and can simultaneously transform impedance.

Equations & Parameters ▸

\(\text{Lattice: }L=\frac{\sqrt{Z_uZ_b}}{2\omega_0},\; C=\frac{1}{2\omega_0\sqrt{Z_uZ_b}} \quad \text{Pi: }L=\frac{Z_{vm}}{\omega_0},\; C=\frac{1}{\omega_0 Z_{vm}}\)

f	Operating frequency.
Z_unbal	Unbalanced port impedance (Ω) — typically 50 Ω coax.
Z_bal	Balanced port impedance (Ω) — e.g. 200 Ω folded dipole.
Topology	Lattice/Bridged-T: wide use. LC π-BALUN: simpler. Marchand: lumped approx.

Physical constants used

c	Speed of light = 2.998×10⁸ m/s
µ₀	Permeability of free space = 4π×10⁻⁷ H/m ≈ 1.2566×10⁻⁶ H/m
ε₀	Permittivity of free space = 8.854×10⁻¹² F/m

Inputs

Frequency, f

Topology

Unbalanced impedance, Z_u

Coaxial port

Balanced impedance, Z_b

Dipole / balanced port

Component Values

Results

Component Values

L₁ = —

C₁ = —

L₂ = —

C₂ = —

Network Performance

Impedance ratio—

Q / bandwidth—

Diagram

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