Efficiencies of Microwave 2-Ports from Reflection Coefficient Measurements (Short papers)

It is well-known that one can determine the efficiency of a microwave 2-port by measuring the reflection coefficient /splGamma/₁ at the input port when the output port is terminated by a sliding short circuit. The locus of Γ₁ is a circle whose radius equals the efficiency η_2m for energy entering port 2 when port 1 is terminated in a nonreflecting load. Similarly η_1m is the radius of the circle when port is terminated in a sliding short circuit. This note describes a procedure for obtaining, from the same measured data, new reflection coefficients Γ_1N and Γ_2N, whose circular loci have radii R_1N and R_2N which give the efficiencies of the 2-port when connected to an arbitrary load of reflection coefficient Γ_L. Thus the Γ₁ or Γ₂ data may be used to obtain the efficiency of the 2-port when terminated in any arbitrary load. The method is potentially more accurate than the 3-point method since errors can be reduced by drawing a circle through many measured points.