RFID Applications

Radio-frequency identification (RFID) is one of the many electromagnetic (EM) applications where WIPL-D software suite is successfully used. RFID assumes the wireless use of electromagnetic fields to transfer data, mostly for the purposes of automatic identification and tracking of various tags attached to target objects.

WIPL-D Pro as a method of Moments based code is very suitable for RFID. Most of the small and less complex tags are simulated in a few seconds. WIPL-D is extremely efficient for open radiating problems and especially for simulation of coupling between very distant objects (no boundary box requirement). WIPL-D Pro does not require to mesh the space between reader and the tag.

Part of the applications of WIPL-D software for devices marked as RFID include common industrial RFID tag (even winded around human wrist), complex RFID Reader at 13.56 MHz, multiband cross spiral tag, quadrifilar spiral antenna with circular polarization for UHF mobile RFID reader.

View PDF

RF Propagation in Mining Tunnels

Due to inherent higher order basis functions, efficient parallelization on multi core CPUs and support for simulations on GPU platforms, WIPL-D software can be effectively used for radio frequency propagation problems. One such problem would be determining power transfer between transmitter and receiver antennas at radio frequency (RF) frequencies in under-ground tunnels of significant length (several hundreds of meters).

The simulation setup involves positioning two antennas (transmitter and receiver) inside a very long tunnel. Usually walls are made of concrete, where characteristics vary: Er between 4 and 7 and Sigma between 0.02 and 0.0002. Tunnel height is 7.2 feet and width is 6 feet. Simulation frequency of interest ar 455 and 915 MHz. The effects of using horizontal or vertical polarization are also discussed. Simulations show comparison of measured and simulated data, where the distance between antennas is spanned between 0 and 500 feet, where simulation time is measured in hours.

View PDF

Frequency Selective Surface

There is a growing demand for new materials to enhance device performances at low cost. For several years, many periodicals there have been published (built from large number of uniform cells) which show that such engineering issues can be resolved.

Numerous cases demonstrate how some typical problems can be solved by using WIPL-D software.

They include: dipole radiation modified by very close FSS at 13 GHz, coupling between dipoles over FSS (WIPL-D is inherently able to calculate very low values of antenna coupling, well below -100 dB), RCS from FSS on dielectric slab (7×7 cells), energy transfer through FSS (additional 30 dB isolation), rectangular horn covered with FSS metallic radome. All models are run on standard desktop PC equipped with inexpensive GPU card. Simulation time is under 1h even for the most complicated cases.

View PDF

Wire Equivalents of Antenna Standoffs

The paper presents an efficient technique to determine equivalents of antenna dielectric standoffs in the form of wires with distributed loadings. The capacitive coupling of the antenna tube with the ground is characterized by capacitance per unit length (e.g. in pF/foot) of the transmission line made by the tube and the ground. Influence of each dielectric standoff can be emulated by wire of properly determined radius and distributed loading. The equivalent radius and the distributed loading are determined by cross-section dimensions of the standoff and its electrical properties (relative dielectric constant). The relative dielectric constant can be determined the tube radius and capacitance per unit length in the presence of dielectric stand. Using reverse engineering, dielectric constant can be emulated if the capacity per unit length is known. If simple and fast model are required for fast simulation and optimization, replacement of the dielectric standoff with wires with distributed loadings is the right approach. It is shown that the results obtained using WIPL-D are very close to the theoretical result, which proves the concept.

View PDF