Abstract: There is provided a system for transmission of power and/or information between a first location external of a living body and a second position internal of the living body which comprises: (a) a primary controller (2) comprising a power source and a transmitter locatable at the first locations; and (b) an antenna (12) based device (10) locatable at the second position to receive an output from the transmitter, wherein the power source is adapted to emit high frequency electromagnetic radiation between 0.5 to 5 GHz. A medical appliance comprising a spring-based stent incorporating a monitoring device wherein the spring of the stent acts as the aerial for the monitoring device and wherein the medical appliance is capable of receiving electromagnetic radiation with a frequency between 0.5 to 5 GHz.