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.
