A method for operating a removable smartphone case is disclosed. The method involves transmitting radio waves below the skin surface of a person, receiving radio waves on a two-dimensional array of receive antennas, the received radio waves including a reflected portion of the transmitted radio waves, generating digital data in response to the received radio waves, wherein the digital data is indicative of a health parameter of the person, and communicating the digital data generated in response to the received radio waves from the removable smartphone case to a smartphone that is connected to the removable smartphone case.
