Modelling and Design of HF RFID Passive Transponders with Additional Energy Harvester

Abstract

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.

Numerical Model of Directional Radiation Pattern Based on Primary Antenna Parameters

“…Since, both data and energy are conveyed between transmitter and receiver (RWD and transponders in which chips are powered by electromagnetic field generated by RWD's antenna) small discrepancies can lead to lack of identification. The interrogation zone (IZ) is the most useful parameter on the stage of designing the RFID systems [20], [21] and it is used as the factor of proper synthesis process. The critical step is to select adequate input data.…”

Development board of the autonomous semi-passive RFID transponder

“…The choice of electromagnetic waves as the medium of conveying power in the proposed autonomous development board follows the new solutions that appear in RFID chips of semi-passive transponders -a few producers offer the possibility to split energy supplied by the RWD to the chip between the internal communication transceiver and additional blocks e.g. sensors, analog-to-digital converters, external outputs, etc [5,8]. Although the foreign electromagnetic field presents in the surroundings supports new transponder functionality of operating autonomously outside the IZ, it is very weak and problems of capturing, storage and converting very low energy to the usable level has to be solved.…”

“…These blocks are designed on the basis of semi-passive chips that have additional wire serial peripheral bus for communication with a supervising controller (HF band: ST M24LR64E chip with I2C bus; UHF band: chip AMS SL900A, SPI bus) [5,8,15]. Moreover, the both ICs can gather energy from the electromagnetic field generated by antennas of RWD, in their operating frequency bands.…”

“…Similar activities are pursued in the areas of reliable and safe identi-P. Jankowski-Mihułowicz, M. Węglarski, G. Pitera, D. Kawalec and W. Lichoń second group -from 860 MHz to 960 MHz (the UHF band) depending on the region of the world [3]. The inductive coupled systems operate by utilizing zone that is characterized by an inhomogeneous magnetic field (described by the magnetic field strength H) and strong coupling (described by the mutual inductance M) between antennas of the arrangement components [8]. On the other hand, the UHF RFID systems work in the range of far-field where emitted wave is not only a data carrier but first of all an energy source (of power density S) [5].…”

“…Generally it is used for enlarging the IZ, what is a very desirable feature for most implementations of RFID systems. Moreover, in some new chips integrated with both wired and wireless access ports [5,8], the additional energy is used for powering blocks of supplementary autonomous functions, such as measuring physical quantities (humidity [9][10], temperature [10][11][12], light intensity [10,11], pressure [13], acceleration [14], gas [12], etc. ), writing gathered data into a built-in memory, managing activity cycles and power distribution in a data acquisition system.…”