RF Notch + Bandpass Filter — Interactive Frequency Response

OK2ZAW  ·  June 2026  ·  Amateur Radio / RF Design

An interactive tool for visualising the insertion loss of a shunt series-LC notch filter and an optional 2-pole coupled-resonator bandpass filter (Z₀ = 2 Ω, BW = 150 kHz) across the 0.2–30 MHz range. Select one or more notch frequencies and an optional BPF centre frequency to see the combined response on the chart. All capacitor values are computed from standard E-series combinations.

Interactive Tool
Notch Filter
80 50
Notch — select band

Select notch frequency
Bandpass Filter
Z₀ = 2 Ω · BW = 150 kHz 80
BPF — select band

Select BPF center frequency
Design parameters
Notch topologyShunt series-LC trap. At resonance, the LC presents a short to ground → notch. f₀ = 1/(2π√LC)
BPF topology2-pole coupled-resonator: Rs → [L+Cs] → Ck shunt → [L+Cs] → RL. Z₀ = Rs = RL = 2 Ω, BW = 150 kHz.
Notch inductors7 bands: 12 µH (0.2–1.8 MHz, series combos), 5.6 / 4.7 / 3.9 / 3.3 / 2.7 / 2.2 µH
BPF inductors6 bands: 5.6 µH (0.2–4.8 MHz), 4.7 / 3.9 / 3.3 / 2.7 / 2.2 µH
Combined curveTotal insertion loss = BPF IL + Σ Notch IL (dB). Shown in dark red when both filter types are active.
Coverage150 BPF centre frequencies at 200 kHz steps, 0.2–30 MHz. 150 notch frequencies at same steps.