The antenna structure has a high frequency wave transmission line that transmits a high frequency wave and an emission antenna part for emitting the high frequency wave supplied via the high frequency wave transmission line. The emission antenna part includes a metal antenna having a rod-like shape and a ceramic layer that covers at least a part of the metal antenna.

The present disclosure relates to an internal combustion engine comprising at least one cylinder, four charge-exchange points per cylinder, wherein a first and a second charge-exchange port are each an inlet port, and wherein a third and a fourth charge-exchange port are each an outlet port, also comprising one spark plug and one prechamber spark plug per each cylinder.

The present disclosure relates to an internal combustion engine comprising at least one cylinder, four charge-exchange points per cylinder, wherein a first and a second charge-exchange port are each an inlet port, and wherein a third and a fourth charge-exchange port are each an outlet port, also comprising one spark plug and one prechamber spark plug per each cylinder.