Stackup Parameters
10 mil
0.254 mm
1 mil
100 mil
5 mil
0.127 mm
1 mil
60 mil
Distance between signal and return trace.
1.4 mil
0.036 mm
0.1 mil
30 mil (0.76mm)
1 oz copper ≈ 1.37 mil (0.035 mm)
4.2
1.0 (Air)
10.0
Quick Presets
Characteristic Impedance (Zo)
--Ω
Inductance
-- nH/in
-- nH/mm
Capacitance
-- pF/in
-- pF/mm
Propagation Delay
-- ps/in
-- ps/mm
Velocity
-- % c
Cutoff Freq (Approx)
-- GHz
Cross Section (Scale Auto-fit)
How this works (The Physics)
This calculator models the Broadside Coupled trace pair. Since one wire is the Return (Ground) for the other, this is physically treated as a balanced transmission line.
The Virtual Ground Model
Because the currents in the Signal and Return paths are equal and opposite, a "Virtual Ground" plane exists exactly halfway between the two traces.
- Effective Height ($h_{eff}$): $H / 2$
- Base Model: Microstrip
Calculation Logic
We calculate the impedance of a single trace to the virtual ground ($Z_{odd}$) using Hammerstad & Jensen's microstrip equations, then double it to get the total loop impedance.
Z0_total = (2 × Z_microstrip) / √εr