In this example, an RFID tag system is examined using XFdtd EM Simulation Software to validate its performance for use in situations where high volume usage requires very low-cost components. The RFID tag is constructed as a microstrip device with spiral resonators tuned to specific frequencies that represent separate bits of the tag code. The resonators are connected to two cross-polarized ultrawide band monopole disk antennas which receive and transmit the signal from the scanning system. The system is demonstrated with a design capable of encoding six bits that are formed by resonances 100 MHz apart between 2.0 and 2.5 GHz. The testing is done using two cross-polarized log period dipole array antennas which transmit and receive the signal from the RFID tag. Download the full paper for more information.