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关键词： Antenna array   artificial magnetic conductor (AMC)   circularly polarized (CP)   crossed-dipole   dual-band   radio frequency identification (RFID)  

摘要： In this article, a low-profile high-efficiency dual-band 0.915/2.45 GHz circularly polarized (CP) antenna and its array are designed for radio frequency identification (RFID) reader applications. First, a dual-band antenna element is introduced to achieve dual-sense CP radiation using two pairs of crossed-dipoles for the first time. The right-hand CP (RHCP) wave at lower hand is mainly produced by the first-order mode on longer dipole, while the left-hand CP (LHCP) wave at upper band is generated by the combination of first-order mode on shorter dipole and third-order mode on longer dipole. An artificial magnetic conductor (AMC) is used to improve the antenna directivity with low profile and makes this antenna easy to integrate into RFID system. Then, a rotated sequential phase feed CP array is proposed, fabricated, and measured. Measured impedance bandwidth (IBW) for vertical bar S-11 vertical bar < -10 dB is more than 40.0% at these two bands. Measured 3 dB axial ratio bandwidths (ARBWs) are 32.0% (0.77-1.06 GHz) and 27.8% (2.22-2.95 GHz). Compared with other dual-band CP reader antennas, which work in 0.915/2.45 GHz RFID systems, this new antenna array has a simpler configuration to achieve dual-band CP radiation. In addition, the 3 dB ARBWs are much wider than the previous antennas. Moreover, because the feeding network of this array is quite simple, the radiation efficiency is very high (>90%), and the peak gains are more than 9.0 and 15.0 dBic at corresponding bands.

关键词： RFID   PEIS   GPS   AOMDV-SAPTV   Clustering mechanism  

摘要： Radio Frequency Identification (RFID) technology is projected to address the issue of handling the bulk of nodes for consequently recognized and tracking tags associated with the objects. Using non-contact radiofrequency electromagnetic fields the information can be transmitted remotely. Tracking is made up of crowded building areas and technology should be low cost. GPS (Global Positioning System) Fleet Tracking is tracking the device when the GPS device is available in the object but, in the crowed building area the efficiency is low and the GPS is very high cost than RFID. AOMDV-SAPTV (Adhoc On-demand Multicast Distance Vector-Secure Adjacent Position Trust Verification) is used multicast routing for the large number of nodes in a network. The method PEIS is for handling the large-scale RFID network and improving the performance of the RFID system using a clustering mechanism. This paper discussed with PEIS (Performance Enhancement with Improved Security), GPS Fleet Tracker, and AOMDV-SAPTV separately and made the comparative analysis between these three technologies and thus concluded that PEIS is the best suitable technology for tracking & locating the objects.

关键词： bird feeding   data validation   GoPro   passive integrated transponder tags   radio-frequency identification   supplemental food   video   visit duration  

摘要： Radio-frequency identification (RFID) technology has gained popularity in ornithological studies as a way to collect large quantities of data to answer specific biological questions, but few published studies report methodologies used for validating the accuracy of RFID data. Further, connections between the RFID data and the behaviors of interest in a study are not always clearly established. These methodological deficiencies may seriously impact a study's results and subsequent interpretation. We built RFID-equipped bird feeders and mounted them at three sites in Tompkins County, New York. We deployed passive integrated transponder tags on black-capped chickadees, tufted titmice, and white-breasted nuthatches and used a GoPro video camera to record the three tagged species at the feeders. We then reviewed the video to determine the accuracy of the RFID reader and understand the birds' behavior at the feeders. We found that our RFID system recorded only 34.2% of all visits by tagged birds (n = 237) and that RFID detection increased with the length of a visit. We also found that our three tagged species and two other species that visited the feeders, American goldfinch and hairy woodpecker, retrieved food in 79.5% of their visits. Chickadees, titmice, nuthatches, and woodpeckers spent, on average, 2.3 s at feeders to collect one seed per visit. In contrast, goldfinches spent an average of 9.0 s at feeders and consumed up to 30 seeds per visit. Our results demonstrate the importance of confirming detection accuracy and that video can be used to identify behavioral characteristics associated with an RFID reader's detections. This simple-yet time-intensive-method for assessing the accuracy and biological meaning of RFID data is useful for ornithological studies but can be used in research focusing on various taxa and study systems.

关键词： Circulators   IoT   RFID   industrial 4.0  

摘要： This article proposes a new technique to extend the use of the UHF RFID technology in IoT applications. The technique is based on segmenting the bandwidth of the UHF RFID into smaller segments with the use of band-pass filters and circulators. The number of band-pass filters (N) used are equal to the number of segments needed, while the number of circulators are equal to (N-1). Subsequently, each of these bandwidth segments is assigned to a specific geographical location/area/zone within a given larger space where an antenna is located. Using the reader, identifying the frequency where the maximum RSSI is received will hence identify its preassigned location/area where tagged object is located. As a proof of concept, in this article the available used-reader band is divided into two segments using two filters and one circulator. The system analysis performed using CST simulations and signal flow graph derived equations. Verification of the technique was done experimentally and location of the tag between the two segments was clearly identified.

关键词： Antennas   Antenna arrays   Radiofrequency identification   Patch antennas   Substrates   UHF antennas   Portals   UHF RFID   right-angled antenna   L-shaped   V-shaped patch antenna   portal antenna   door frame  

摘要： This paper presents a conformal ultra-high-frequency (UHF) radio frequency identification (RFID) reader antenna array for doorway portal applications. The dual-patch antenna is only 100 mm wide and right-angled (V-shaped) to fit the corners of a regular portal. Patches are arranged orthogonally to create horizontal and vertical-linearly polarized fields at near-zones and at far-field distances they provide slant-polarized fields. Beam steering is enabled by phase delaying the array elements to enhance the field coverage within the doorway portal. The antenna operates in the European UHF RFID band (865-868 MHz) with a 38 MHz, 10 dB impedance bandwidth. The antenna's azimuth and elevation half-power beamwidth is 90 degrees and 130 degrees. The azimuth beam is tilted to 35 degrees from the boresight where the gain is peaked at 5.5 dBi. This antenna is low-profile, low-cost and flame retardant and paintable. Inherited properties of the antenna's substrate make the antenna non-toxic, self-extinguishing, lightweight and highly chemical resistant. The reader antenna is compatible with both RAIN and non-RAIN alliance UHF RFID readers.

关键词： RFID   face recognition   data augmentation   neural network  

摘要： Face recognition (FR) has been widely used in many areas nowadays. However, the existing mainstream vision-based facial recognition has limitations such as vulnerability to spoofing attacks, sensitivity to lighting conditions, and high risk of privacy leakage, etc. To address these problems, in this paper we take a sparkly different approach and propose RFaceID, a novel RFID-based face recognition system. RFaceID only needs the users to shake their faces in front of the RFID tag matrix for a few seconds to get their faces recognized. Through theoretical analysis and experiment validations, the feasibility of the RFID-based face recognition is studied. Multiple data processing and data augmentation techniques are proposed to minimize the negative impact of environmental noises and user dynamics. A deep neural network (DNN) model is designed to characterize both the spatial and temporal feature of face shaking events. We implement the system and extensive evaluation results show that RFaceID achieves a high face recognition accuracy at 93.1% for 100 users, which shows the potential of RFaceID for future facial recognition applications.

关键词： Eavesdropping   RFID   Sub-mm Level Vibration  

摘要： The unprecedented success of speech recognition methods has stimulated the wide usage of intelligent audio systems, which provides new attack opportunities for stealing the user privacy through eavesdropping on the loudspeakers. *** eavesdropping methods employ a high-speed camera, relying on LOS to measure object vibrations, or utilize WiFi MIMO antenna array, requiring to eavesdrop in quiet environments. In this paper, we explore the possibility of eavesdropping on the loudspeaker based on COTS RFID tags, which are prevalently deployed in many corners of our daily lives. We propose Tag-Bug that focuses on the human voice with complex frequency bands and performs the thru-the-wall eavesdropping on the loudspeaker by capturing sub-mm level vibration. Tag-Bug extracts sound characteristics through two means: (1) Vibration effect, where a tag directly vibrates caused by sounds;(2) Reflection effect, where a tag does not vibrate but senses the reflection signals from nearby vibrating objects. To amplify the influence of vibration signals, we design a new signal feature referred as Modulated Signal Difference (MSD) to reconstruct the sound from RF-signals. To improve the quality of the reconstructed sound for human voice recognition, we apply a Conditional Generative Adversarial Network (CGAN) to recover the full-frequency band from the partial-frequency band of the reconstructed sound. Extensive experiments on the USRP platform show that Tag-Bug can successfully capture the monotone sound when the loudness is larger than 60dB. Tag-Bug can *** recognize the numbers of human voice with 95.3%, 85.3% and 87.5% precision in the free-space eavesdropping, thru-the-brick-wall eavesdropping and thru-the-insulating-glass eavesdropping, respectively. Tag-Bug can also accurately recognize the letters with 87% precision in the free-space eavesdropping.

关键词： Shunt regulator   power detector   PWM power detector   power regulation   RFID   IoT  

摘要： The paper presents a novel shunt voltage regulation architecture that uses an RF power detector, based on Pulse Width Modulation (PWM) technique, aiming at magnetic coupled Radio-Frequency Identification (RFID) transponders. The proposed regulator architecture implements two feedback loops: a voltage clamping circuit that composes a fast correction loop and a slow but accurate power detector loop. The first clamping loop guarantees fast over-voltage protection, mainly in high RF power condition (short reading distance), but degrades power efficiency when in low power condition (large reading distance). The second loop corrects the imprecision of the first loop according to the detected RF input power. Therefore, it increases power efficiency and reading distance when in low RF power condition. The RF power detector architecture, based on a PWM technique, and the shunt regulator design are presented and discussed in detail. RFID power regulation issues are also discussed, followed by a brief review of RF power detector circuits. The complete regulator architecture was implemented in a 180 nm CMOS low cost process and prototyped as part of a commercial low-frequency (134 kHz) RFID transponder. The complete transponder area is 870 x 870 mu m(2), being 130 x 230 mu m(2) related to the regulator circuit only. Both resonant and supply capacitors are implemented on chip. The analog and digital functional blocks of the RFID system consume 4.5 mu W. Performance of the transponder is measured with the shunt regulator enabled and compared with the power limiting approach using only clamping diodes. Measured results show an improvement of 16.7% in the maximum communication distance between the transponder and the reader because of the proposed regulation strategy.

关键词： human-robot interaction   social robots   waymarking   radio frequency identification   RFID   signaling   navigation   wayfinding   topological   indoor  

摘要： Travellers use the term waymarking to define the action of posting signs, or waymarks, along a route. These marks are intended to be points of reference during navigation for the environment. In this research, we will define waymarking as the skill of a robot to signal the environment or generate information to facilitate localization and navigation, both for its own use and for other robots as well. We present an automated environment signaling system using human-robot interaction and radio frequency identification (RFID) technology. The goal is for the robot, through human-robot interaction, to obtain information from the environment and use this information to carry out the signaling or waymarking process. HRI will play a key role in the signaling process since this type of communication makes it possible to exchange more specific and enriching information. The robot uses common phrases such as "Where am I?" and "Where can I go?", just as we humans do when we ask other people for information about the environment. It is also possible to guide the robot and "show" it the environment to carry out the task of writing the signs. The robot will use the information received to create, update, or improve the navigation data in the RFID signals. In this paper, the signaling process will be described, how the robot acquires the information for signals, writing and updating process and finally, the implementation and integration in a real social robot in a real indoor environment.

关键词： antenna   RFID   metal   curved surfaces  

摘要： This paper presents a flexible low-profile antenna suitable for tagging onto metal curved surfaces. The novelty of the proposed antenna lies in the design of an extended ground plane and folding it to realize the bottom layer to shield against metal surfaces. This method reduces the manufacturing complexity as no vias are required in the fabrication process. In addition, the antenna impedance for metal and non-metal surfaces could be obtained through a slight tuning of the slot length. The antenna was realized using a novel low-cost thermal ink transfer process and integrated with a radiofrequency identification chip to successfully demonstrate passive wireless communication at 915 MHz. From the wireless results, a maximum read distance of 1.86 m was obtained for the proposed antenna on metal, compared to a distance of 0.31 m for a reference dipole antenna on metal. Furthermore, the return signal strength indicator pattern obtained show a good correlation to the radiation pattern. The effect of different metal sizes and different metal curvatures were investigated, and results suggest that the effect of these parameters on the impedance mismatch and corresponding power transfer coefficient is not significant. The results are promising for the use of antennas in tagging metal surfaces in the airplane, automotive and unmanned aerial vehicle industries.