An investigation of a six-port microwave measurement system

In the microwave range of frequencies, the performance of phase measurements is generally more difficult than the determination of the magnitude of a given signal. Vector-voltmeters and network analyzers introduced during the last 15 years have certain disadvantages related to high complexity and frequency limitations. However, it has been found that a six-port can be employed to determine the complex circuit parameters of active and passive circuits. Using two of the ports as inputs for 'reference' and 'unknown' signals, power measurements at the remaining four ports, or side-arms, as they are called, provide sufficient information for the calculation of the relative amplitude and phase of the 'unknown' signal. Phase is not measured directly. It is determined from four scaler power measurements.