Reactance / Resonance / Q
Fast checks for Xl, Xc, resonance frequency, series Q, and estimated resonator bandwidth.
Ready.
Xl (ohms)N/A
Xc (ohms)N/A
Net X = Xl - Xc (ohms)N/A
|Z| with series R (ohms)N/A
Series Q = |X|/RN/A
Resonance f0 (MHz)N/A
Estimated BW = f0/Q (MHz)N/A
Damping ratio (R / 2*sqrt(L/C))N/A
Sizing from Target |X| at Current Frequency
L for target X (nH)N/A
C for target X (pF)N/A
- Xl = 2 * pi * f * L
- Xc = 1 / (2 * pi * f * C)
- f0 = 1 / (2 * pi * sqrt(L * C))
Interpreting Reactance, Resonance, and Q in Practice
This calculator gives quick first-pass numbers during matching and filter exploration. It is especially useful when selecting initial L/C values, estimating resonance movement, and checking whether resistive loss dominates the expected selectivity.
What each output tells you
- Net X: sign and magnitude indicate whether the branch behaves net inductive or capacitive at the test frequency.
- Series Q: higher values generally imply sharper selectivity but stronger sensitivity to tolerance and drift.
- Estimated bandwidth f0/Q: rough guide for early sizing, not a replacement for full network simulation.
Practical workflow
- Start with target reactance values near your intended matching topology.
- Check resonance position against desired band center.
- Iterate with realistic component ESR, package parasitics, and layout extraction before release.
Limits to remember
Real resonant networks show frequency-dependent loss and parasitic coupling. For high-confidence design decisions, verify with measured S-parameters or EM/co-simulation data, then compare the measured trend against this baseline.