Electromagnetic Compatibility Measurement Technology
by Alexandra Zange
With the introduction of cable television, there came a demand to measure the screening attenuation of the coaxial cables (CATV cables) used here as a decibel value (dB) up to 1000 MHz instead of the transfer impedance in mOhm/m. This is done by means of absorbing clamps. For this purpose, the method with absorbing clamps was already introduced in the 1970s and 1980s.
Lauri Halme developed the summing function and the coupling transfer function of cable screens in 1987. Halme and Otto Breitenbach recognized that the maximum values of the resonances in the triaxial measuring tube at higher frequencies represent the screening attenuation. On this basis, Breitenbach, together with Thomas Hähner, extended the triaxial method for measuring screening attenuation in the frequency range from approximately 30 MHz onwards.