Near field communication (NFC) based on radio frequency identification (RFID) has become a standard in modern technology. At the heart of all RFID systems is the tag – an inductive coil or antenna usually connected to a small microchip. Since most RFID tags in common use are passive and don’t carry any power source, the power to run the tag must be supplied by the interrogating reader through near-field or far-field coupling. Full-wave electromagnetic simulation can capture the behavior of RFID devices in great detail, making it possible to accelerate their design by reducing the number of physical prototypes required. The operation of an RFID system can be very sensitive to other objects in the environment, and electromagnetic interference or shielding effects can affect their performance. These effects can also be predicted, and remedies designed, at a simulation level.

For the purposes of simulation, RFID systems can be divided broadly into two groups: low frequency (frequencies up to tens of megahertz) and high frequency (hundreds of megahertz or greater). LF RFID tags are typically inductive coils which are designed for close range communication in applications such as secure contactless payment and identification. They are very much smaller than the wavelength at the operating frequency and are thus best simulated using frequency domain techniques.

HF RFID systems on the other hand offer higher data rates and longer ranges, making them suitable for applications such as inventory tracking and electronic toll collection. In HF RFID tags, the coil acts as a radiating antenna, usually tightly folded to reduce its area. In order for the small antenna to operate efficiently, the impedance of the HF RFID tag needs to be optimized to provide a conjugate match to the impedance of the microchip to which it is attached. HF RFID tags can be simulated using time domain or frequency domain techniques, depending on the antenna geometry and environment.

This talk gives an overview about different solver techniques for RFID and NFC simulations, including parametrization, optimization, antenna tuning and matching, and how these tools can help the designer perform system level analysis in complex and realistic environments.