In this paper, authors disclose the methodology of interrogation zone synthesis that comprehensively covers all aspects connected with determination of RFID device parameters. The effective methods of involved parameter determination for passive and semi-passive UHF RFID chips are presented. The elaborated measuring procedures have been verified experimentally and are discussed in details. The special untypical laboratory stand has been prepared for carrying out the research tasks. Furthermore, the importance of the parameters for the interrogation zone synthesis is described methodically. In addition, the special software tools that allow researchers to effectively conduct investigations on protocol parameter modifications both in new-developed as well as approved standards (e.g. ISO/IEC 18000-6c) have been designed. These facilities can significantly support many theoretical and simulation works that are developed and described in the branch literature and can improve the reliability and efficiency of designed RFID applications.

The huge progress in electronics technology and RFID technique gives the opportunity to implement additional features in transponders. It should be noted that either passive or semipassive transponders are supplied with energy that is derived from the electromagnetic field generated by the read/write device and its antenna. This power source is used to conduct radio-communication process and excess energy could be used to power the extra electronic circuits, but the problem is to determine the additional power load impact on the RFID system proper operation and size of interrogation zone. The ability to power the supplementary electronic blocks applied in the HF passive transponders is discussed in detail this paper. The simulation model and test samples with a harvester that recovers energy from the electromagnetic field of read/write device and its antenna have been developed in order to conduct investigations. The harvested energy has been utilized to supply a microprocessor acquisition block for LTCC pressure sensor developed in research previously described by authors.

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Ukazuje się od 1919 roku 01'15 Ukazuje się od 1919 roku 04'15 Organ Stowarzyszenia Elektryków Polskich  Wydawnictwo SIGMA-NOT Sp. z o.o.

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The results of technological investigations in the scope of inkjet-printed flexible RFID antennas dedicated to UHF transponders and also problems with the application of nanomaterials are reported in this paper. The design of the antenna electrical circuit and the parameters of the inkjet printing process were elaborated on the basis of the numerical model prepared in the Mentor Graphics HyperLynx 3D EM software. The project evaluation was performed by measuring electrical parameters of the structures printed with silver-based conductive inks. The obtained results confirm coincidence between the model and its implementation in the inkjet printing technology. Finally, the prepared antenna has been applied in an RFID transponder of UHF band and the functional tests are also reported in this paper.

A general view on the problem of designing atypical battery-free, autonomous semi-passive RFID transponders-sensors (autonomous sensors with RFID interfaces) is presented in this review. Although RFID devices can be created in any of the electronic technologies, the design stage must be repeated each time when the manufacturing processes are changed, and their specific conditions have to be taken into consideration when modeling new solutions. Aspects related to the factors affecting the synthesis of semi-passive RFID transponder components on the basis of which the idea of the autonomous RFID sensor was developed are reflected in the paper. Besides their general characteristics, the operation conditions of modern RFID systems and achievements in autonomous RFID sensor technology are revealed in subsequent sections—they include such issues as technological aspects of the synthesis process, designing antennas for RFID transponders, determining RFID chip and antenna parameters, creating the interrogation zone IZ, etc. It should be pointed that the universal construction of an autonomous RFID sensor, which could be use in any application of the automatic object identification system, cannot be developed according to the current state of the art. Moreover, a trial and error method is the most commonly used in the today’s process of designing new solutions, and the basic parameters are estimated on the basis of the tests and the research team experience. Therefore, it is necessary to look for new inventions and methods in order to improve implementations of RFID systems.

The authors paid particular attention to the problem of antenna impedance measurements in the RFID technique. These measurements have to be realized by using two ports of a vector network analyzer and dedicated passive differential probes. Since the measurement process and estimated parameters depend on the frequency band, operating conditions, type of the system component and antenna designs used, appropriate verification of the impedance parameters on the basis of properly conducted experiments is a crucial stage in the antenna synthesis of transponders and read/write devices. Accordingly, a systematized procedure of impedance measurements is proposed. It can be easily implemented by designers preparing antennas for different kinds of RFID applications. The essence of indirect measurements of the differential impedance parameters is discussed in details. The experimental verification has been made on the basis of a few representative examples.