**3.3.2 Improvement of direct comparison transfer by inserting passive components**

To obviate the *ΓG*, an intermediate component is proposed to use to increase the accuracy. If put an attenuator or an isolator on the source output, the reflection coefficient of a generator is improved. But low power is a problem for inserting an attenuator and being limited in frequency range is a problem for isolators (Rumfelt & Elwell, 1967).

A leveling circuit or ratio measurement can avoid the troubles. Resistive power splitter or directional coupler is normally used as the intermediate component and constructing the leveling circuit.
