Abstract: Microwave-Electro-Thermal thrusters produce a high temperature rocket exhaust by sending microwaves into a resonant cavity where an excited mode then creates an electrodeless discharge that heats gaseous fuel. Heretofore, the microwave power coupling between the microwave generator and the resonant cavity and plasma has consisted of rigid waveguide with impedance matching equipment. This waveguide and impedance matching hardware greatly adds to the weight and size of the system making it impractical for spaceflight. The foregoing problems are overcome by greatly reducing or eliminating the waveguide and impedance matching equipment.