This research investigates the feasibility of using ammonia as a propellant in a 17.8-GHz microwave electrothermal thruster. Microwave electrothermal thrusters are a type of electric propulsion that use microwave energy to heat a gaseous propellant to plasma temperatures followed by nozzle expansion, thus generating thrust. This study examined the performance of a low-power microwave electrothermal thruster for use on CubeSats and small spacecraft. This makes it favorable for deep space missions.