Cherish Bauer-Reich

A Printed Rampart-Line Antenna with a Dielectric Superstrate for UHF RFID Applications

A printed Rampart line antenna with a dielectric superstrate for passive radio frequency identification (RFID) tags is presented. A design process is outlined to determine the number of elements used in the rampart line antenna to achieve the required gain for the desired read range. An inductive loop is then added to the port to match the antenna with the passive tag circuitry. It is shown that a passive tag with a printed Rampart line antenna and a dielectric superstrate can achieve comparable read ranges to commercially available passive RFID tags.

UHF RFID impedance matching: When is a T-match not a T-match?

The T-match is a frequently cited impedance matching technique for UHF RFID tags. However, there appear to be many misconceptions about what the term “T-match” actually implies and when the relevant assumptions no longer apply. This work focuses on creating a clear definition of the T-match design space in order to differentiate it from other impedance matching techniques. A comparison between analytic solutions and numerical simulations shows that the analytic solution is valid only in those cases where very close spacing (s ≤ 0.009λ) between the dipole and T-match arms is maintained, and the length of the T-match is relatively short (l2≤ 0.06λ).

An investigation of the viability of UHF RFID for subsurface soil sensors

A study was performed to assess the viability of using ultra-high frequency (UHF) radio frequency identification (RFID) to communicate with subsurface sensors. The results showed that, when the reader operated near the FCC limit, read ranges for the sensorwere greater than a half meter for soil moisture levels of 15% by weight or less. Moisture levels at 15% or greater resulted in significant attenuation or complete loss of signal. Tags also had desireable read ranges for depths up to 15 cm.

Low-profile, high-permeability antennaless RFID tags for use on metal objects

Radio-frequency identification (RFID) systems are used in asset tracking, but general-purpose tags typically do not perform well on or near metal. Therefore, custom solutions for on metal applications are common. Many solutions for on-metal tags use spacers or electromagnetic band-gap structures resulting in designs that are extremely thick. Our approach was to incorporate materials with permeabilities greater than 1 to create an impedance across a metal surface, diverting current into the tag IC. This type of tag is nearly antennaless as it uses the ground plane or container to excite currents through the IC. Our research has shown that these tags are sensitive to several parameters, such as the size and shape of the plane upon which they are placed, the material used in the antenna, and the type of matching network being used. Tags using magnetic materials in this manner are significantly thinner than those developed using other methods.

The Effects of ESD in Multiple Testing Environments on Adhesive-Label RFID Tags

The purpose of this study was to determine the ESD susceptibility of commercially available label-enclosed RFID tags. Six different types of adhesive labels with RFID transponders were subjected to ESD in different testing environments. Initial data shows that most of the tags were sufficiently protected from fairly large discharges by their covering material. The magnitude of discharge and distance of the discharge to the IC did not have the expected effects on the tags. Instead, the presence of a ground plane and low label resistance were correlated to larger damage rates. The type of antenna and IC also played a role in susceptibility.

The Interaction of Electrostatic Discharge and RFID

Electrostatic discharge, or ESD, is a common hazard in the electronics industry. Despite the fact that RFID has been in use for nearly forty years, there has been little to no discussion in the scholarly literature on how ESD interacts with RFID tags as a system. The intent of this chapter is to give the reader an overview of ESD and the aspects of RFID with which it interacts. Next, a view of ESD protections incorporated into RFID ICs is presented. A statistical examination of RFID tag susceptibility is summarized, and the chapter ends with a discussion of ESD issues that affect the RFID manufacturing environment. This document should, therefore, provide the reader with a comprehensive view of the interaction of RFID with ESD as well as a starting point for studying related areas.

On the effect of mutual coupling on LF and UHF tags implemented in dual frequency RFID applications

The performance of many different dual frequency tag configurations were tested in a commercially available dual frequency RFID system. It has been shown that the interaction between the LF and UHF tags can have a significant impact (i.e., 91.84% reduction in read range) on the performance of each individual tag. But, in all cases it has been shown that by proper placement of the LF and UHF RFID tags the performance of each individual tag in the dual-frequency tag can be preserved. In the Rampart line case to preserve the performance of an individual tag a larger footprint was not needed.

The effect of EUT position on Gigahertz Transverse Electromagnetic (GTEM) cell correlation algorithms

Previous work has shown that the transverse and longitudinal position of an emissions source within a gigahertz transverse electromagnetic (GTEM) cell will affect the measured voltages at the apex of the cell. Since the emissions source(s) on an EUT may not always correspond with the measurement position origin, this may have an effect on the correlation algorithm used to simulate radiated emissions at an open-air test site (OATS). This paper analyzes why such measurement differences occur and shows the effect shifts in the emissions source location relative to the measurement position origin has on two correlation algorithms. Specifically, it examines the 3-position total radiated power algorithm and the 9-position multipole algorithm.