A microwave measurement system for obtaining continuous burning-rate information from a solid propellant slab-burning rocket motor is described. A previous derivative-based method for reducing the microwave data is reviewed and an improved data reduction technique is introduced. The improved microwave modeling technique is analyzed using simulated data to determine the accuracy of the burning-rate calculations and the sensitivity of the burning-rate calculations to errors in the model parameters. The microwave model is then used to calculate the burning rate of the propellant for a selected firing of the slab motor. / Master of Science