Beam Scanning UHF RFID Reader Antenna with High Gain and Wide Axial Ratio Beamwidth

A novel ultra-high-frequency (UHF) RFID reader antenna is proposed, designed and measured. The proposed antenna is capable of 2-dimensional (2D) beam-scanning from 0º to 360º in the azimuth plane, and 0º to 40º in the zenith plane. The minima of the antenna's axial ratio (AR) follows its gain maxima during beam-scanning, resulting in an equivalent 3 dB AR beamwidth of over 136º for every phi cut. Moreover, the antenna's AR can be easily modified without affecting other parameters. It is shown experimentally that the antenna's 2D beam-scanning ability and the improved AR performance lead to better tag-reading results, improving the percentage of missing tags by up to 21.6% compared to a standard antenna which has a degraded AR and only supports 1D beam-scanning. In addition, the antenna needs no matching network and has a -10 dB return loss bandwidth from 860 MHz to 880 MHz.This work was supported by EPSRC EP /S-19405/1 Channel Optimised Distributed Passive Sensor Network

A UHF RFID Reader Antenna with Tunable Axial Ratio and Fixed Beamwidth

A novel ultra-high-frequency (UHF) RFID reader antenna is proposed. The antenna has a unique property as being able to change its axial ratio (AR) without affecting its gain, beamwidth or impedance matching performance, enabling the isolated study of the effect of different axial ratios in RFID tag reading.This work was supported by EPSRC EP /S-19405/1 Channel Optimised Distributed Passive Sensor Networks

Enhanced RFID tag detection accuracy using distributed antenna arrays

© 2018 IEEE. An Ultra High Frequency (UHF) Radio Frequency Identification (RFID) system using distributed antenna arrays for interrogating RFID tags in a highly multipath environment is demonstrated. The system makes use of phase diversity and beam steering to overcome fading. The tag detection accuracy is compared to a standard fixed antenna system, showing that the presented system is able to deliver more power to the more challenging tags, and therefore is capable of a higher tag read success rate. It is also shown that, whereas a fixed antenna is capable of scanning a single cell, the ability of a phased array to scan through 360° azimuth leads to a reduction in number of antennas required for a multicell system. The experimental results are validated using a 3D field-based propagation model, which enables visualisation of the power distribution in the field of interest, and provides insight into the improved system performance

On the Accessibility of Adaptive Phenotypes of a Bacterial Metabolic Network

The mechanisms by which adaptive phenotypes spread within an evolving population after their emergence are understood fairly well. Much less is known about the factors that influence the evolutionary accessibility of such phenotypes, a pre-requisite for their emergence in a population. Here, we investigate the influence of environmental quality on the accessibility of adaptive phenotypes of Escherichia coli's central metabolic network. We used an established flux-balance model of metabolism as the basis for a genotype-phenotype map (GPM). We quantified the effects of seven qualitatively different environments (corresponding to both carbohydrate and gluconeogenic metabolic substrates) on the structure of this GPM. We found that the GPM has a more rugged structure in qualitatively poorer environments, suggesting that adaptive phenotypes could be intrinsically less accessible in such environments. Nevertheless, on average ∼74% of the genotype can be altered by neutral drift, in the environment where the GPM is most rugged; this could allow evolving populations to circumvent such ruggedness. Furthermore, we found that the normalized mutual information (NMI) of genotype differences relative to phenotype differences, which measures the GPM's capacity to transmit information about phenotype differences, is positively correlated with (simulation-based) estimates of the accessibility of adaptive phenotypes in different environments. These results are consistent with the predictions of a simple analytic theory that makes explicit the relationship between the NMI and the speed of adaptation. The results suggest an intuitive information-theoretic principle for evolutionary adaptation; adaptation could be faster in environments where the GPM has a greater capacity to transmit information about phenotype differences. More generally, our results provide insight into fundamental environment-specific differences in the accessibility of adaptive phenotypes, and they suggest opportunities for research at the interface between information theory and evolutionary biology

Interactions between Schistosoma haematobium group species and their Bulinus spp. intermediate hosts along the Niger River Valley

Background Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is endemic in Niger but complicated by the presence of Schistosoma bovis, Schistosoma curassoni and S. haematobium group hybrids along with various Bulinus snail intermediate host species. Establishing the schistosomes and snails involved in transmission aids disease surveillance whilst providing insights into snail-schistosome interactions/compatibilities and biology. Methods Infected Bulinus spp. were collected from 16 villages north and south of the Niamey region, Niger, between 2011 and 2015. From each Bulinus spp., 20–52 cercariae shed were analysed using microsatellite markers and a subset identified using the mitochondrial (mt) cox1 and nuclear ITS1 + 2 and 18S DNA regions. Infected Bulinus spp. were identified using both morphological and molecular analysis (partial mt cox1 region). Results A total of 87 infected Bulinus from 24 sites were found, 29 were molecularly confirmed as B. truncatus, three as B. forskalii and four as B. globosus. The remaining samples were morphologically identified as B. truncatus (n = 49) and B. forskalii (n = 2). The microsatellite analysis of 1124 cercariae revealed 186 cercarial multilocus genotypes (MLGs). Identical cercarial genotypes were frequently (60%) identified from the same snail (clonal populations from a single miracidia); however, several (40%) of the snails had cercariae of different genotypes (2–10 MLG’s) indicating multiple miracidial infections. Fifty-seven of the B. truncatus and all of the B. forskalii and B. globosus were shedding the Bovid schistosome S. bovis. The other B. truncatus were shedding the human schistosomes, S. haematobium (n = 6) and the S. haematobium group hybrids (n = 13). Two B. truncatus had co-infections with S. haematobium and S. haematobium group hybrids whilst no co-infections with S. bovis were observed. Conclusions This study has advanced our understanding of human and bovid schistosomiasis transmission in the Niger River Valley region. Human Schistosoma species/forms (S. haematobium and S. haematobium hybrids) were found transmitted only in five villages whereas those causing veterinary schistosomiasis (S. bovis), were found in most villages. Bulinus truncatus was most abundant, transmitting all Schistosoma species, while the less abundant B. forskalii and B. globosus, only transmitted S. bovis. Our data suggest that species-specific biological traits may exist in relation to co-infections, snail-schistosome compatibility and intramolluscan schistosome development

Performance improvements of multicast RFID systems using phased array antennas and phase diversity

© 2017 IEEE. We present the results of a new Ultra High Frequency (UHF) Radio Frequency Identification (RFID) system using multiple, distributed, phased array antennas for interrogating RFID tags over wide areas. The system makes use of signals multicast over two steerable antenna arrays with phase diversity to overcome fading. The system is compared to two other methods for driving the two arrays; one with the more widely used time division multiplexing and beam steering, and another with multicast signals and beam steering but without phase diversity. It is shown that the new system outperforms both of these in terms of tag RSSI and tag read success rate. The results are validated using a 3D field-based simulator, which enables visualisation of the power distribution in the field of interest

Enhanced RFID tag detection accuracy using distributed antenna arrays

© 2018 IEEE. An Ultra High Frequency (UHF) Radio Frequency Identification (RFID) system using distributed antenna arrays for interrogating RFID tags in a highly multipath environment is demonstrated. The system makes use of phase diversity and beam steering to overcome fading. The tag detection accuracy is compared to a standard fixed antenna system, showing that the presented system is able to deliver more power to the more challenging tags, and therefore is capable of a higher tag read success rate. It is also shown that, whereas a fixed antenna is capable of scanning a single cell, the ability of a phased array to scan through 360° azimuth leads to a reduction in number of antennas required for a multicell system. The experimental results are validated using a 3D field-based propagation model, which enables visualisation of the power distribution in the field of interest, and provides insight into the improved system performance

Dataset For: Performance Improvements of Multicast RFID Systems using Phased Array Antennas and Phase Diversity

Data supporting Performance Improvements of Multicast RFID Systems using Phased Array Antennas and Phase Diversit