Abstract
This paper presents methods for evaluating, expressing and using the uncertainty associated with complex S-parameter measurements. The methods are based on internationally recommended guidelines, published by the International Organization for Standardization (ISO), with extensions to accommodate the complex nature of the measurands. The treatment of measurements from both one-port and multi-port devices is presented and this is used to propagate uncertainty from complex-valued S-parameters to radio frequency (rf) and microwave quantities derived from these. A simple example, involving the comparison loss correction used during a microwave power meter calibration, is included to demonstrate the principles of propagating the uncertainty in complex S-parameter measurements.