New method for measuring transfer impedance and transfer admittance of shields using a triaxial cell

Two performance parameters of a cable or connector shield are its surface transfer impedance Z/sub T/ and its surface transfer admittance Y/sub T/. A new method for measuring these properties is presented. The use of two different terminations for the cable or conductor under test (CUT) allows one to determine both Z/sub T/ and Y/sub T/. Through characterization of the inner and outer transmission lines of the triaxial cell, using time domain reflectrometry, Z/sub T/ and Y/sub T/ can be determined in amplitude as well as in phase. The phase is obtained by de-embedding the measured S-parameters up to the CUT. The de-embedding of the measurements also allows one to extend the frequency range up to 3 GHz. To illustrate this method a solid shield with a circular aperture and a coaxial cable with a braided shield have been measured and compared, respectively, with theoretical predictions and published results.