vswr and impedance matching sript

Signal Processing Group Inc. designs, develops and manufactures analog and RF/wireless ASICs and modules

A symmetrical microstrip gap can be modeled by two open ends with capacitive series coupling between the two ends. The equivalent circuit also produces two parallel capacitances at both ends.This script calculates the capacitances


Microstrip gap


Microstrip gap


(DISCLAIMER) The numerical error of the capacitive admittances for this calculation is less than 0.1mS for the following limits:

0.1 ≤ W1/H ≤ 3
0.1 ≤ W2/H ≤ 3
1≤ W2/W1≤3
0.2≤S/H ≤∞
0.2 Ghz≤f≤18 Ghz

W1 is width of microstrip 1 and W2 is width of microstrip 2. S is the gap between them. ε is the permittivity of the substrate.


H ( Height of microstrip, thickness of substrate, mm):
W1 (Width of microstrip1, mm):
W2 (Width of microstrip2, mm):
T (Thicknes of microstrip, mm):
ε (Relative permittivity ):
Z01 (Characterisitic Impedance of first microstrip, Ohms):
Z02 (Characterisitic Impedance of second microstrip, Ohms):
S (Microstrip gap, mm):


Cs Value (pF) :
CP1 Value (F) :
CP2 Value (F) :

Please refer to the limitations of the calculation noted at the top of the page