Abstract: A system is provided for wireless transmission of data and/or power using an on-body antenna apparatus (40) and an implant device inside the body. The system comprises the implant device and the on-body antenna apparatus (40) as well as an antenna control system. The implant device, is for use within the body and comprises an implant antenna (16) arranged to receive wirelessly transmitted power and/or to wirelessly transmit data. The on-body antenna apparatus (40) is arranged to transmit power and/or data acting as a radiative antenna, wherein the on-body antenna apparatus (40) comprises a pair of patch antennas (42) arranged to be placed on the surface of the body (44) spaced apart from one another to form an antenna circuit that is coupled by the body tissue around and between the patch antennas (42).

Abstract: An implant device 12 for use within the body comprises: a data source; and a non-self-resonant antenna for backscatter communications with an external communication system. The non-self-resonant antenna comprises at least two electrodes 16 including two conductive patches 16 that are arranged to be spaced apart when the implant device 12 is in use The implant device 12 is arranged to control the backscattering properties of the non-self-resonant antenna in order to thereby transmit data from the data source to the external communications system. The implant device 12 is arranged such that the backscattering properties of the non-self-resonant antenna are controlled by one or more electrical switch(es) 14 including an electrical switch that is arranged to change the impedance of the non-self-resonant antenna by switching between coupling the at least two electrodes 16 via body tissue 18 and coupling the at least two electrodes 16 via a conductive pathway.

Abstract: An implant device (12) for use within the body (22) comprises: a data source (14); and an antenna (32) for backscatter communications with an external communication system (24); wherein the implant device (12) is arranged to control the backscattering properties of the antenna (32) in order to thereby transmit data from the data source to the external communications system. The antenna (32) can have a configuration for backscatter communications that comprises a meandering path extending from a start (42) of the meander at a capacitive coupling fed by a coupling patch (38) to an end (46) of the meander connected to a ground plane (44). The backscattering properties of the antenna (32) can be controlled by one or more electrical switch(es) (50, 52) that change the load and/or geometry of the antenna (32).