Calculate microstrip characteristic impedance Z₀, trace width W, effective permittivity εe, and quarter-wave length for FR4 PCB substrate. Interactive calculator with formula reference.
Use 50 Ω traces throughout — avoid impedance steps that cause reflections
Keep 50 Ω traces as short as possible to minimize FR4 dielectric loss
Ground plane must be solid (no cuts) directly beneath RF traces
Avoid vias in the signal path at frequencies above 1 GHz (via inductance ~1 nH/mm)
FR4 εr tolerance is ±10% lot-to-lot — design with margin or use controlled-impedance PCB service
RF View Microstrip Calculator: RF View's built-in Microstrip Calculator supports FR4, Rogers RO4003C, RO4350B, RT/Duroid 5880, and custom substrates. Results feed directly into the Auto Matching synthesizer. Available offline in the Utilities tab of the free Android app.