RF source characterization of Tire Pressure Monitoring System

The growing part of electronic embedded systems in automotive applications is motivated by the drastic requirements in transport safety and by the reduction of fuel consumption. Today more and more vehicles are equipped with the Tire Pressure Monitoring System (TPMS) in Europe and USA. The TPMS market is a natural offshoot of the industry's push for higher levels of comfort and security. In the USA this system becomes obligatory: however for safety, ecologic and economic reasons these sensors are largely used. To ensure the good reception of the data transmitted from the sensors via a RF carrier, a good knowledge of our wireless radio-link channel is mandatory. Thus, the transmitter part of the system must be properly described: the RF source characterization for TPMS is discussed in this paper. We propose an original approach to characterize the source, from the transmitter antenna to the whole wheel system: the influence of each element (lumped antenna, rim, tire and ground effects) is quantified by successive embedding around the antenna. Several experimental studies are performed in far and near field conditions for a complete characterization.