L Matching Network Calculator

L-Network Impedance Matching Tool

Input Fields

Source resistance

Rs

Ω

Source resistance (input impedance)

Load resistance

Rl

Ω

Load resistance (output impedance)

Operating frequency

f

MHz

Frequency in megahertz (MHz)

CalculateReset

Calculate automaticallyIf enabled, the result will update automatically when you change any value.

Your Results

Quality Factor (Q)

Series Reactance

Parallel Reactance

Series Inductance

Parallel Capacitance

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L Matching Network Design Formula

$$Q = \sqrt{\frac{R_L}{R_S} – 1}$$ $$X_S = Q \cdot R_S$$ $$X_P = \frac{R_L}{Q}$$

Where:

• $$R_S$$ = source resistance (Ω)
• $$R_L$$ = load resistance (Ω)
• $$Q$$ = quality factor
• $$X_S$$ = series reactance (Ω)
• $$X_P$$ = parallel reactance (Ω)

These formulas are used when matching a low source impedance to a higher load impedance using an L-network. The values for inductance or capacitance can then be derived based on the reactances and frequency.

L Matching Network – Calculation Example

Given:

• $$R_S$$ = 50 Ω
• $$R_L$$ = 200 Ω

Calculation:

1. $$Q = \sqrt{\frac{200}{50} – 1} = \sqrt{3} \approx 1.732$$
2. $$X_S = Q \cdot R_S = 1.732 \cdot 50 = 86.6~\Omega$$
3. $$X_P = \frac{R_L}{Q} = \frac{200}{1.732} \approx 115.5~\Omega$$

L matching networks are widely used in RF and microwave engineering where precise impedance transformation is required between a source and load. Depending on whether the source impedance is greater or less than the load impedance, the configuration changes between “high-pass” and “low-pass” topologies. Once the required reactances are calculated, you can convert them to capacitance or inductance using the operating frequency. This tool simplifies and automates the first step of impedance matching design.