An adapter structure for transferring an electromagnetic signal between an electronic component and an antenna, the adapter structure includes an adapter body having a base surface. The adapter structure further includes at least one ridged adapter waveguide channel, wherein the at least one adapter waveguide channel extends from the base surface into the adapter body. The adapter structure further includes an electromagnetic band gap structure with a plurality of band gap elements, wherein the band gap elements are spaced apart relative to each other, project from the base surface and have a front face spaced apart from the base surface. At least one band gap element is arranged as extension of a ridge of an associated adapter waveguide channel.