Ignition unit and system

An ignition unit (100) produces an ignition in a combustion chamber of a combustion engine in the following manner. The ignition unit comprises a radiofrequency resonator (117, 118) that radiates a plasma-creating radiofrequency field into the combustion chamber. The ignition unit further comprises a microwave resonator (113) that radiates a plasma-boosting microwave field into the combustion chamber. In an embodiment, the microwave resonator (113) has an output surface (115) to which the combustion chamber is exposed when the ignition unit is fitted on the combustion engine. The radiofrequency resonator may comprise an electrode (118) that is at least partially embedded in the microwave resonator (113). The electrode may have a tip (120) that is located at a distance from the output surface (115) so that the microwave resonator (113) provides a barrier between the tip (120) and the output surface (115).