The article presents an analysis of various technical solutions focused on correction of amplitude and amplitude-phase distortions of modulated signals that occur in vacuum and solid-state microwave power amplifiers as a result of nonlinear changes of instantaneous current values in active amplifying devices. It is shown that intermodulation distortions of odd orders in the vicinity of the input signal main frequency band degrade the amplifier’s power efficiency and give rise to additional side spectrum components, which violate strict requirements for electromagnetic compatibility for radio electronic devices and lead to the necessity to operate the amplifier well below its power rating for reducing the distortion levels. It is noted that there is a tendency toward increasing the information transmission rate in microwave bands along with growing requirements for the mass, dimensions, and reliability of automatic on-board satellite equipment. In view of these circumstances, after the period during which structural digital-and-analog and fully digital solutions were elaborated, some developers turn back to analog solutions that do not require introduction of complicated digital-and-analog components into the microwave signal flow path and open the possibility to widen the information frequency band of transmitted signals. The article presents the results from studying a microstrip linearizer on its simulation model. The linearizer model contains nonlinear elements made using domestically produced high-speed Schottky diodes with decoupling circuits on the basis of two hybrid microstrip bridges. The model of a standard traveling-wave tube (TWT) with an 11 GHz central frequency that takes into account the AM/AM and AM/PM distortions occurring in this TWT is used as the active component. The measurement results have shown that in case of using the optimal combination of linearizer parameters, the modulated signal input power in its main band can be increased by 2 dB in comparison with the TWT without the linearizer, with concurrently decreasing the level of side spectrum distortion by 12 and 21 dB for third- and fifth-order components, respectively. The microstip predistortion diode linearizer development results can be used in constructing a satellite on-board radio transmitting equipment with improved characteristics.