Disclosed herein is an implantable electronic device including a housing containing an electrical circuit. The implantable electronic device further includes an antenna assembly coupled to the electrical circuit. The antenna assembly includes an antenna including a dielectric antenna body within which an antenna trace is disposed. Portions of the antenna trace are disposed in offset transverse layers in a non-overlapping arrangement, thereby reducing capacitive coupling between the layers of the antenna trace. In certain implementations, the antenna assembly includes one or more capacitive features that selectively overlap portions of the antenna trace and facilitate tuning of the antenna.