A method for monitoring a health parameter in a person involves engaging an alignment feature of a health monitoring device with an alignment feature of an alignment element that is worn on the skin, transmitting radio waves from at least one transmit antenna of the health monitoring device below the skin surface of the person while the alignment feature of the health monitoring device is engaged with the alignment feature of the alignment element that is worn by the person, receiving radio waves on a two-dimensional array of receive antennas of the health monitoring device while the alignment feature of the health monitoring device is engaged with the alignment feature of the alignment element that is worn by the person, generating digital data that corresponds to the received radio waves, and determining a value that is indicative of a health parameter of the person in response to the digital data.
