Impedance Matching Calculator
Calculate L-network inductor and capacitor values for RF impedance matching between source and load impedances.
What Is Impedance Matching?
Impedance matching aligns source and load impedances so maximum power reaches the load. RF circuits, antennas, and transmission lines use matching networks to reduce reflection and improve efficiency.
L-Network Matching
An L-network uses one inductor and one capacitor. When load resistance exceeds source resistance, a common low-pass match places a series inductor at the load and a shunt capacitor at the source.
$$Q = \sqrt{\frac{R_L}{R_S} - 1}$$ $$X_L = \frac{R_L}{Q}, \quad X_C = Q \cdot R_S$$Inductance and capacitance follow $L = X_L / (2\pi f)$ and $C = 1 / (2\pi f X_C)$.
When to Use L-Match
L-networks are simple and work well for narrowband matching. For wider bandwidth or complex impedances, Pi-match or T-match topologies may be better.
Related tools: Cable Impedance Calculator and Baud Rate Calculator.
Frequently Asked Questions
What is the quality factor Q in matching?
Q describes how selective the match is. Higher Q gives a narrower bandwidth but can achieve larger impedance transformation with smaller components.
What if source and load resistance are equal?
An L-network cannot match two equal resistances alone. Add a small mismatch or use a different topology if reactance must be tuned.
Do I need to enter reactance?
Enter zero for purely resistive loads. Nonzero source or load reactance shifts the required L and C values to cancel that reactance.
What is a low-pass L-match?
It passes DC and low frequencies while blocking higher harmonics. Series inductor and shunt capacitor is the usual arrangement when $R_L > R_S$.
Which frequency unit should I use?
MHz is convenient for RF design. The calculator converts Hz, kHz, MHz, and GHz internally before computing component values.
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