A system for monitoring a health parameter in a person is disclosed. The system includes at least one transmit antenna configured to transmit millimeter range radio waves over a 3D space below the skin surface of a person, multiple receive antennas configured to receive radio waves, the received radio waves including a reflected portion of the transmitted radio waves, and means for isolating a signal from a particular location in the 3D space in response to receiving the radio waves on the multiple receive antennas and outputting a signal that corresponds to a health parameter of the person in response to the isolated signal.