An external antenna with a plurality of concentric primary coils recharges an implantable medical device with a secondary coil when the primary coils are placed in proximity of the secondary coil. Selection circuitry determines which of the plurality of concentric primary coils has the most efficient coupling with the secondary coil and drive circuitry drives the selected primary coil with an oscillating current. During a recharge session, selection circuitry periodically checks at least some of the primary coils to determine whether the primary coil with the most efficient connection has changed. An antenna housing may hold the primary coils in a rigid planar relationship with each other or the primary coils may shift with respect to each other, forming a cup-shape around a bulge in the skin created by the implantable medical device.
