Oilfield drilling utilizes downhole data transmitted to surface for formation evaluation and steering of directional wellbores. A leading technology in providing subsurface to surface communication is Electro-Magnetic (EM) Telemetry. This technology is typically employed with a downhole antenna concentric with the bore of an electrically insulating “gap sub” portion of the system. The antenna blocks the bore from further use to conduct other sensors or equipment through. One aspect of the invention is to integrate the antenna into the structure of the gap sub, thereby clearing the bore for conducting other tools through, and also protecting the antenna from the harsh drilling environment, including abrasion, erosion, shock, and vibration. Another aspect of this invention enables the antenna to serve a secondary function as an anti-rotation feature between the two halves of the gap sub.