Development of an improved version of sample holder for measuring the shielding effectiveness of planar films

An improved version of a coaxial sample holder with continuous inner conductor for measuring the shielding effectiveness of planar films is presented. Keeping the design idea of the previously realized version of inner conductor split in two parts that are screwed on the sample under test, new aspects are: presence of tapered transitions, compact realization, and overall small size (total length less than 150 mm; maximum diameter of the cylindrical device of 48 mm). The theoretical only TEM mode maximum frequency is about 5 GHz. The assembly of the device is easy, as it is the sample preparation. Experimental data have been get in the range 0.1 MHz-3 GHz by using a vector network analyzer. The reliability of the system has been proved by using, as reference samples, copper and aluminium thin films deposited by DC magnetron sputtering on kapton substrates. Films with different thicknesses have been prepared, with values around a few hundreds of nanometers, as measured by using a surface profiler. The shielding effectiveness experimental data of the used reference samples are reported and are well in agreement with the theoretical values.