A Personal Computer Based System for the Rapid Display of Smith Chart Curves Using 6-Ports

Abstract

In an increasing number of applications it is required to accurately measure the reflection coefficient of a component in a transmission medium different from that of the RF test equipment through an adapter which may have a substantial mismatch. A classical example would be the measurement of a waveguide component using coaxial test equipment such as that based on 7mm line through a coax to waveguide adapter. In an ever increasing number of applications one is required to measure a component in stripline, NIC, or monalithic circuitry using coaxial test equipment. To obtain sufficient accuracy it is frequently necessary to perform a computerized correction for the error introduced by the adapter mismatch. In the first part of this paper it is demonstrated that the 6-port approach can lead to a very rapid determination of P, in those cases where computerized correction of measurement data is necessary, because of the simplicity of the mathematical computations involved. The second part of the paper describes a working system based on an 8 bit personal computer.