Broadband UHF implanted 3-D conformal antenna design and characterization for in-off body wireless links
Christoph Schmidt, Félix Casado, Aitor Arriola, Iñaki Ortego, Peter D. Bradley and Daniel Valderas
IEEE Transactions on Antennas and Propagation, vol. 62, issue 3, pp. 1433-1444
A broadband UHF antenna for implanted central venous catheters (CVC) is designed, implemented, and properly characterized. According to the requirements, the CVC antenna (CVCA) is low profile, surface integrated, and 3-D conformal to a 16 mm base radius, 10 mm upper radius, and 16 mm high truncated cone. It operates at the MedRadio band (401-406 MHz) for implant communication and at the ISM 2.45 GHz band for electronics wake up. A prototype implementation including a test-bed within a phantom that is representative of a body is introduced. The antenna exhibits S11 <;-10 dB at the bands of interest with broadband behavior. The measured gain is -28.95 dBi in vertical and -36.9 dBi in horizontal polarization in the MedRadio band and -25.5 dBi and -19.9 dBi at 2.45 GHz. The gain is corroborated by the link characterization between an implanted node with electronics and an external base station. Base station antenna, electronics sensitivity, transmitted power, and path loss are independently measured and introduced in a broken down link budget for read range estimate. This is 18.95 m for the MedRadio band in free space conditions. By using the power saving mode at 2.45 GHz, it is reduced to an estimate of 1.88 m.