Analysis of a two-port flanged coaxial holder for shielding effectiveness and dielectric measurements of thin films and thin materials

A two-port flanged coaxial probe for measuring the dielectric and magnetic properties of thin material sheets is analyzed. Closed form solutions for the two-port scattering parameters are presented. The solution assumes an incident TEM wave together with evanescent TM_0n modes. Numerical results are obtained for both the forward and inverse problem. Computations indicate that at low frequencies the incident waves are almost totally reflected. As the frequency is increased, transmission through the sample increases. Experimental results compare closely with the theory. The inverse solution yielded good permittivity determination for the cases tested. The technique should prove useful for nondestructive testing of circuit boards or substrates