High power amplifier is a very significant component in satellite communication and it is very important to analyze its performance according to the satellite application it is used in. Noise power ratio, also known as carrier to inter-modulation noise ratio is an important parameter for analyzing the performance of high power amplifiers. All power amplifiers are nonlinear to some degree. If more than one carrier is received by a single amplifier, mixing or inter-modulation processes will take place. The inter-modulation analysis becomes complex as the number of carriers are increased in the transmitted signal. In order to analyse inter-modulation distortion products, NPR measurement technique is employed. The book highlights the significance of NPR measurement and also provides MATLAB based simulated results of noise power ratio measurement using high power amplifier models. The simulated results are compared with the actual results and the accuracy of the simulator along with the amount of systematic error is determined for every IPBO value.