A New Method for Measuring Impedance at Microwave Frequencies by Use of Directional Couplers

ABSTRACT

A method for measurement of impedance by use of directional coupler and combination of an accurate attenuator of negligible insertion loss and a phase shifter is introduced. The side arm of the coupler is terminated in the load and the main arm is terminated by the attenuator and the phase shifter. In special cases the two terminations can be interchanged. The reflected power, as sampled out by an auxiliary coupler, is made to vanish by adjustment of the attenuator and the phase shifter. The method is independent of characteristics of detecting crystal used and of the padding between the microwave source and the rest of the system.

The method introduced also yields coupling coefficients of directional couplers.