Heavy oil recovery using downhole radio frequency radiation heating accelerates SAGD thermal recovery processes. In one embodiment, one or more SAGD well pairs traverse a subterranean formation for recovering heavy oil. The SAGD well pairs each create a steam chamber which, over time, expands to allow each steam chamber to interact with one another and in this way, increases the recovery heavy oil from the formation. One or more antennas may be interposed between the steam chambers to introduce electromagnetic radiation into the formation to heat the fluids therein to accelerate expansion of the steam chambers, particularly where antennas are judiciously situated to optimize steam chamber expansion. Where an infill production well is present, the antennas may be situated to accelerate steam chamber communication with the infill production well. Advantages include lower cost, higher efficiencies, quicker and increased hydrocarbon recovery.