A power transfer device is a power transmitter (201) or a power receiver (205) conducting power transfer using an electromagnetic power transfer signal employing a repeating time frame comprising a power transfer time interval and an object detection time interval. A power transfer circuit (303, 307) comprises a power transfer coil (203, 207) receiving or generating the power transfer signal during the power transfer time intervals. A communicator (315, 323) communicates with the other device via an electromagnetic communication signal. A communication resonance circuit (317, 321) comprises a communication antenna (319, 325) for transmitting or receiving the electromagnetic communication signal. During the communication, the communication resonance circuit (317, 321) provides a resonance at a first resonance frequency to the communicator (315, 323). A controller (333, 335) adapts the communication resonance circuit to not provide the resonance at the first resonance frequency to the communicator during object detection time intervals. The approach may provide improved detection of resonance objects, such as smart cards (e.g. NFC cards).