In this paper, dual operation E-shape and U-shape Patch Antenna feed by transmission line is presented. The proposed antenna is designed on a two-layer (FR4 & Air) substrate with an area of 35 mm by 40 mm. The dual operation frequencies are 4.7 GHz and 5.4 GHz. A (-10 dB) bandwidths of return loss S11 characteristic for the dual band are 4.6 % and 4.3 % respectively. E-plane and H-plane for the dual operation frequencies is satisfactory within this bandwidth. Return loss and E-plane and H-plane radiation patterns are provided.
These paper deals with RFID system and in particular with the ”loading effect”. We often confuse the load-modulation with the loading effect. If the load modulation is well known, it is not the case of the loading effect. We focus in particular on the loading effect due to the shunt regulator in the tag. We search a law of these shunt regulator to improve and/or reduce the loading effect.
Framed Slotted ALOHA (FSA) is an anti-collision technique in the currently most popular standard of RF-ID systems in the UHF domain, the ISO/IEC CD 18000-6. The number of tags present in the field is a crucial parameter to apply FSA algorithms in an optimal manner to achieve the highest detection rate possible. Therefore, a lot of effort is spent on the estimation of this parameter and a range of different estimation techniques exist. One of the most promising techniques is the minimum squared error (MSE) estimator for expectation values formulated by Vogt et al. for completely observed frames. This technique has not yet been adapted to an in-frame adjustment of the frame size (i.e. without quitting the interrogation round), as it is favoured in the aforementioned standard. In this work the MSE is reformulated to work on slot-by-slot basis and an efficient algorithm is proposed to exploit the on-the-fly adjustment of the frame size. The results are compared to other common estimation techniques for the tag population with respect to cumulated estimation error and detection rate. Furthermore, it is demonstrated that the performance is approximating the theoretical bound obtained by the maximum likelihood estimator.
The continual growing field of applications for Contactless Smartcards and NFC (Nearfield Communications) leads to the occurrence of several close coupled labels in the operating field. This close coupling leads to additional physical effects, as a strong mutual interaction between labels results. It is topic of this work to characterize the physical behavior of such close coupled systems exemplary in terms of effected resonance frequency and seen voltage at the label. Mathematical methods as well as typical application scenarios based on simulation are pointed out, characterizing the influence on the performance.
The traditional meaning of RFID is to identify an object without contact. There is usually a requirement in these cases that the object must not use battery or power supply. This article deals with a new feature, which is the hiding of the object. It means there would be a requirement to identify an object without risk uncovering by unauthorized.
We present a method to perform accurate measurements in the UHF (ultra high frequency) band on passive RFID (radio frequency identification) transponder chips. Our samples were extracted from commercially available RFID tag inlays. We determine the minimum operating power necessary to get a response from the transponder chip. Furthermore, we measure the chip input impedance in both, the reflecting and the absorbing state as a function of input power. We present measurement results of four transponder chips and find good agreement with values claimed in the manufacturer’s data sheets. At the end of the paper we draw conclusions for the optimum antenna design and the link budget.
Currently RFID (radio frequency identification) technology is pushing to the market mainly forced by industry. Passive tags in the UHF (ultra high frequency) region are of particular interest e.g. for supply chains, showing a tendency to become state of the art. Passive tags obtain their energy from the readers during communication. The reader has to power the tag by radiating energy at the same time as it has to receive the tag answer. Due to this so-called self-interference the reader frontend design becomes more complex than that of typical communication systems. In this paper we present the implementation of a modular UHF reader frontend for a flexible RFID testbed.
One of the crucial performance parameters in RFID systems is the throughput of inventoried tags. Framed Slotted ALOHA (FSA) is deployed as anti-collision technique in the currently most popular standard of RF-ID systems. In order to maximize the throughput in such systems it is necessary to estimate the number of tags in the field exactly. This paper presents a throughput enhancement based on the fact that some observed states have a low probability of occurrence independent from the number of tags in the field. Thus, is becomes beneficial for the throughput to restart the frame in these cases.
We present a method for automated analysis of Reader Command modulation pulses for the ISO/IEC 14443 Type A air interface. Interoperability, which can be assured by this method, is a necessary pre-condition for secure and efficient communication. To achieve an H-field strength in the specified range efficiently, a Reader antenna with a high Q-factor is required. This Q-factor can simply be determined from the antenna equivalent circuit. A high Q-factor, however, also means longer time constants and so takes influence on the modulation. We investigate pulse parameters as described in the standard for ideal conditions, present a method for automated measurement in detailed steps and verify this method with practical measurements for different Q-factors of the antenna specified in the ISO/IEC 10373-6 laboratory standard. Results and alternative options are discussed with regard to the specific requirements of the broadband RFID system.
In this article, we would like to summarize the problems, that may arise in a so called “Intelligent Shopping Cart”, a special shopping cart, which is able to recognize the wares equipped by RFID tags. The shopping cart is able to register the wares- collected in the cart - with EPC standard GEN2 UHF RFID passive tags. Using a wireless communication technology, the central database is accessible, we can retrieve product information and send information about the wares currently in the cart. There are several ways to ensure this functionality, and several problems may arise.