A Multicarrier Communication Method to Increase Radio Coverage for UHF RFID

The method introduced in this paper shows a multicarrier communication to increase coverage in a multipath environment for UHF RFID systems. A characterization of the combined radio channel in ideal (absorber chamber) and in real measurement environment with multipath propagation is presented. Positive effects of different transmit frequencies as well as coverage improvement in real measurement environments are shown. Predictions are made about spatially given dead points and their compensation is described. Furthermore, the shown approach helps to overcome them by significantly improving the transponder coverage with a multicarrier system. The use of a multicarrier transmission leads to a coverage of almost 70%, while the coverage of the single frequencies is below 40%. The geometrically defined rules used for the calculation of the interference pattern agree with a deviation of max. 2 dBm with the measurements.