Insertion Loss Measurements in a 5 Ohm System

This paper describes a technique to measure insertion loss of filters in a 5 ohm system over an extended frequency range and under full load from 14 KHz to 10 GHz. This technique required development of extended range buffer networks and electromagnetic shielding requirements in excess of 120 db. Techniques have been developed for measuring high power, high attenuation, rf powerline filters in impedances that sometimes approximate actual operating impedances. Present specifications and standards require updated and improved measurement techniques. The frequency range of present measurements under full-rated load is limited to 100 KHz through 20 MHz and the circuit impedance is kept at 50 ohms. This provides inadequate and misleading information about the performance of the filter under actual operating conditions. By use of techniques described in this paper, meaningful measurements that simulate actual operating conditions can be achieved. It further describes insertion loss measurements that were performed on a filter measured in a 5 ohm system, under full load conditions, over the extended frequency range from 14 KHz to 10 GHz by employing extended frequency range buffer networks.