A miniaturized UWB antenna for implantable data telemetry

This paper presents a miniaturized impulse radio ultra-wideband (IR-UWB) antenna which is designed for transcutaneous, short-distance data communication used in multichannel neural recording. In these systems, with the increasing number of recording channels, data rates of 10-100 Mbit/s must be transmitted with very limited power and area. Therefore, the antennas are designed as planar, ellipsoidal dipoles on a high permittivity substrate with ε_r = 10.2 to achieve high radiation efficiency with small physical size. In order to increase the robustness against misalignment, a circularly polarized antenna is used at the external receiver unit, reducing the signal power variation under angular misalignment. For the transmitting antenna a miniaturized prototype with an integrated pulse generator was designed on a round shaped PCB with a diameter of only 14mm. Measurements through porcine skin in the frequency domain show an attenuation of less than 30dB in the intended frequency band between 6 and 8.5GHz. Additional evaluations in the time domain prove possible pulse repetition rates of up to 100MHz at a transmission distance of 1.5cm.