Microwave Rocket is considered to be a future mass transportation system to space. Thrust is generated by high-pressure air isometrically heated by millimeter wave irradiation from the ground. High-power and high-frequency operation has been achieved mainly because of the improvement of a millimeter wave generator, gyrotron. Thrust was measured in a high-duty-cycle condition with a high-power millimeter wave. As a result, 30 N of time-averaged thrust was recorded at 91 kW of time-averaged power, which corresponds to 330 N/MW of thrust-to-power ratio.
