Time of arrival based localization of UWB transmitters buried in lossy dielectric media

An algorithm for subsurface localization of UWB transmitters in homogeneous dielectric media is presented. In combination with surface estimation algorithms for UWB pulse radars it allows localization behind arbitrarily shaped medium surfaces. We propose a localization system operating in the FCC UWB frequency range from 3.1 to 10.6 GHz consisting of a transmitter optimized for radiation in high permittivity media and of external radar sensors. The sensors scan the dielectric surface and also measure the time of arrival (ToA) of the signal transmitted from inside of the medium. The transmitter location is estimated by combining the measured ToA data with the knowledge about shape and position of the medium. Therefore a method to calculate wavefront refraction on the medium boundary based on the Huygens-Fresnel principle is derived. The performance of the proposed localization method is verified using electro-magnetic field simulations and measurements. The measurements have been performed with the transmitter placed in high permittivity tissue-mimicking liquid. The localization results are compared with the manually measured transmitter position showing a good agreement.