A Microwave Amplifier is a device for enhancing the output power signal of a microwave device, usually by increasing the amplitude or height of the wave that directly relates to its power level. This is accomplished by channeling additional input power to the microwave device so that its microwave radiation carries more energy.

Such amplifiers are usually operated at low frequencies of the radio wave spectrum, which range around 300 megahertz or higher, and they are used for a variety of purposes from broadband communications to radar systems and electronic warfare by the military.

Several different types of microwave amplifier designs exist including the Gyrotron, the Klystron, and the Amplitron, which is also known as the Crossed-Field Amplifier (CFA) or Platinotron.