The Axem Lab
Founded in 2003, AXEM Technology is a major player in the fields of RFID and mobile devices for 15 years. is a major international player in RFID and mobile terminals associated with RFID, through the design, manufacture and distribution of identifiers (tags, technical labels, cards...) and RFID readers (OEM, industrial, desktop and integrated into tablets, PDAs and smartphones) with a focus on quality and service.
Axem Technology's activity has increasingly evolved towards the design of RFID products through its RFID laboratory: the Axem Lab. Our engineers design, manufacture and measure unique products for specific projects in order to be as close as possible to customers' expectations.They can adapt existing products as well as create new ones (tags, labels, antennas, readers, etc...).
These products are designed and manufactured in limited series in Axem Lab for larger scale production in factories, once the prototype has been validated.
The Axem Lab includes EM simulation software for the design, machines to manufacture customized products as well as instruments for measuring product performance in an anechoic chamber.
In the Axem Lab, research has been conducted to propose a compact tag antenna for metallic object applications. The 10 x 10 x 2.07 mm achieves a read distance of 21 cm with EIRP power of 1.64 Watt when fixed on a metallic object thanks to its antenna made of a loop structure on FR4 substrate with a chip on the side.
Analysis, design and measurements of an ultra-small on metal UHF RFID tag antenna in Axem Lab
An RFID system is composed of tags, readers and antennas which transmit radio-frequency signals between tags and readers.
A successful RFID system depends a great deal on the tag antenna.
Indeed, its design must comply with the application and the environment integration such as: compact size, metal compatibility, antenna gain, robustness and reliable operation over long distances. Yet the antenna design is complex for two main reasons: firstly, the chip has small resistance and large reactance.
Consequently, it is difficult to match the antenna impedance. Secondly, ensuring the antenna performance when introduced in different surfaces, for example in metallic objects, is a key issue.
Essia Ben Abdallah, PhD in Optical and Radiofrequencies, has worked on the design of a miniature UHF RFID tag antenna for metallic objects. The dimensions of the tag are 10 x 10 x 2.07 millimeters (0.03λ x 0.03λ x 0.006λ).
Design of the tag
The antenna was designed and simulated with CST MWS. This 3D Electromagnetic simulation software allows the modeling of the antenna and its environment, the simulation and computation of the characteristics of the antennas.
The antenna of the tag has been designed with a copper loop structure on two millimeters thick FR4 substrate (εr = 4.3, tgδ = 0.025) with a chip on the side as presented in figure 1. The metal thickness (h) is 35 μm cooper.
The chip has been placed on the side to generate an E field maximum vertical component to the antenna plane in order to reduce the metal plate effect.
Prototyping the tag
Axem Technology has a specific die machine (figure 2) to integrate chips on antennas. The chip was integrated on antennas using conductive glue as shown on the final prototype tag antenna. (figure 3)
Characterization and validation
The Axem Lab is equipped with Vector Network Analyzers (VNA) (figure 4) to characterize an antenna (measurements of S parameters, Z impedances). It is a tool to measure the antenna adaptation (parameters S11, S12, S21, S22) with a frequency range from 100 KHz to 3 GHz and a dynamic of 122 dB.
One of a tag’s key features is its reading distance capabilities. Axem Lab has advanced machines to measure the reading performance of any tag: RFID anechoic chamber and Tagformance RFID (figure 5).
These test and measurement machines for HF and UHF RFID tags allow the setting and sensitivity of the tags to be checked. They also analyze the effects of materials and label orientation, measure the performance of RFID tags and optimize RFID tag installations.
The measurements of the tiny on metal tag have been conducted in the anechoic chamber. Simulated and measured reading distances are shown in figure 6. The tag achieves a 16 cm reading distance for a 1.64 Watt EIRP instead of 19 centimeters obtained in simulations at 868 MHz. A slight difference is observed and is due to the relative permittivity of the FR4.
Thus, thanks to cutting-edge RFID technology, Axem Technology's engineers design unique products with specific software, create prototypes, characterize and measure product performance with appropriate equipment.