Module 6.4 Quarter-wavelength Transformer


Task:
Given the load resistance \(R_{L}\) and source impedance \(Z_{g}\), find the characteristic impedance \(Z_{0}\) of the transmission line so that the impedance is matched.
( \(R_{L}\) is transformed to \(Z_{g}\) at the center of Smith chart. Error less than 3% is acceptable.)

  \(R_{L}\)= \(\Omega\)
  \(Z_{g}\)= \(\Omega\)
  \(Z_{0}\)= \(\Omega\)

Introduction:

Learn how to perform impedance matching using a quarter-wavelength transformer. Impedance matching is achieved when
\(Z_{g}\)、\(Z_{0}\) and \(R_{L}\)are in geometric progression.

\(\frac{Z_{0 } }{Z_{g}}=\frac{R_{L } }{Z_{0 }}\implies Z_{0 } = \sqrt {Z_{g}R_{L }}\)

Parameters:

\(R_{L}\):Load resistance
\(Z_{g}\):Source impedance, reference impedance of Smith chart
\(Z_{0}\):Characteristic impedance
\(Z_{in}\):Input Impedance