Method and device for introducing microwave energy into a combustion chamber of a combustion engine

Method for introducing microwave energy into a combustion chamber of an internal combustion engine in which the microwaves enter the combustion chamber via a microwave window, wherein the microwaves are guided at the periphery of the combustion chamber after passing through the microwave window and are coupled radially into the combustion chamber. Correspondingly, in the device for introducing microwave energy into a combustion chamber of a reciprocating internal combustion engine with at least one cylinder with cylinder head and combustion chamber in the cylinder head, at least one hollow waveguide annular space running around the combustion chamber at the periphery with at least one supply for the microwave and with at least one exit opening for the microwave arranged between the hollow waveguide annular space and the combustion chamber is arranged. An internal combustion engine has the features of the device. The method and the device allow precise control of the beginning of volume ignition of a fuel-air mixture in a combustion chamber, so that an optimal low-emission combustion of the fuel is achieved with an efficiency increased compared to conventional reciprocating internal combustion engines. Generally, the invention enables safe ignition of lean fuel-air mixtures.