Broadband Frequency Domain Screening Measurements on RF-Cables

The measurement of screening effectiveness on cable assemblies is very difficult to perform over broad frequency ranges (e.g. from several kHz to more than 3 GHz). A new type of test set-up has been developed and tested with a transmission type wire injection principle. The main advantages of the new wire injection set-up are: - Inherent broad bandwidth due to proper matching of the injection circuit (about 10 kHz up to several GHz) - Backward and forward coupling measurements (to detect directive effects) are feasible without changing the set-up - The preparation of the cable under test (CUT) is simple and easy - Bending, twisting and moving of the CUT is possible during measurement - Very high dynamic range (transfer impedance values below 1 ¿¿/m or approximatively 160 dB screening attenuation are measurable) - set-up hardware (excluding measuring instruments) is very simple and inexpensive Comparative measurements have been performed on eleven different cable types with a triaxial set-up and two wire injection set-ups with 50 ¿ and 100 ¿ characteristic impedance. The agreement is generally better than ± 4 dB between the triaxial and wire injection test results.