The 10 most-cited articles in Electronics Letters, 2022

Abstract The emerging fluid antenna technology enables a high‐density position‐switchable antenna in a small space to obtain enormous performance gains for wireless communications. To understand the theoretical performance of fluid antenna systems, it is important to account for the strong spatial correlation over the different positions (referred to as ‘ports'). Previous works used a classical, generalised correlation model to characterise the channel correlation among the ports but were limited by the lack of degree of freedom of the model to imitate the correlation structures in an actual antenna. In this letter, it is proposed to use a common correlation parameter and to choose it by setting the correlation coefficient of any two ports to be the same as the average correlation coefficient of an actual fluid antenna taking up a linear space. A closed‐form expression for the spatial correlation parameter is first derived assuming that the number of ports is large, and it is illustrated that the correlation parameter depends only on the size of the fluid antenna but not the port…

Abstract Based on Chebyshev polynomials, the two‐way slant range is first approximated by the fourth‐order polynomial approximation. With the series reversion method, the point target reference spectrum (PTRS) which is further used for the development of imaging algorithm in this letter is obtained. The presented method processes the echoed signal corresponding to each transmitter/receiver pair. And then a high‐resolution synthetic aperture sonar (SAS) image is obtained by coherently superposing all coarse‐resolution images. Comparing the peak sidelobe ratio (PSLR) and integration sidelobe ratio (ISLR), the performance of the presented method is superior to that of the traditional method. Simulations are further validated by the presented method.

Abstract A long sequence always contains long‐term dependency problems, which leads to paragraph‐based sentiment analysis being a very challenging task and difficult to evaluate by using a simple RNN network. It is proposed in this letter to use a stacked CARU network to extract the main information in a paragraph. The resulting network also points out how to use a CNN‐based extractor to explore complete passages and capture useful features in their hidden state. In particular, instead of using the Softmax function, the Naïve‐Bayes classifier is connected to the end of the CNN‐based extractor. The proposed models also take into account the conditional independence of the observed results under the hidden variables, which aims to project features into a probability distribution appreciated for its simplicity and interpretability. The advantages of these models in sentiment analysis are empirically investigated by combining the usual classifiers with the results of GloVe embedding on the SST‐5 and IMDB datasets.

Abstract Fluid antenna multiple access (FAMA) is a new way of accommodating a large number of users on a single channel for massive connectivity, with slow FAMA ( s ‐FAMA) being the practical version for achieving this. The impressive performance is understood to be achievable if the users have independent Rayleigh fading envelopes. With mobile networks vamping up the operating frequencies in 5G and beyond, nevertheless, the channel will have less multipath and become more directional. It is unclear if s ‐FAMA still performs well and how its performance is affected by different channel parameters. To address this, this letter first develops a multipath fading channel model capable of modelling a mixture of directional line‐of‐sight (LoS) and non‐LoS paths over the ports of a fluid antenna system. The results indicate that a large number of paths in the channel is essential to the performance and a large Rice factor will degrade the performance rapidly. Also, contrast to the initial belief, the size of the fluid antenna plays a more important role than the number of ports or…

Abstract Ischemic stroke is the most common brain disease. Segmentation of the stroke lesion from a medical scan is vital to plan the surgical procedure. The purpose of this work is to develop an efficient network based on self‐attention and spatial‐channel attention mechanisms. In this letter, a novel multi‐encoder transformer (METrans) is proposed, which overcomes the inability of U‐Nets to model long‐range contextual interactions. Different from traditional segmentation methods, four encoders with different scales are explored to extract the multi‐scale features. Then, the feature maps are fed into a transformer for global feature modelling. The proposed methodology is tested on ATLAS, ISLES 2015, and ISLES 2018 datasets. The extensive experimental results suggest that METrans achieves consistent improvements over the state‐of‐the‐art for segmentation tasks.

Abstract This paper reports the first wireless thermometric device enabled using a surface‐mount capacitor microchip as the sensing element, offering a low‐cost, disposable, and flexible sensor potentially suitable for a wide range of application areas. The device is developed in the form of a resonant‐circuit chip, in which a Y5V‐type multilayer capacitor microchip that exhibits significant temperature dependence serves as a thermoresponsive element that varies the resonant frequency of the circuit upon a temperature change. The wireless sensor chips prototyped in conjunction with the flex‐circuit technology are tested to show their intended function with the frequency responses of up to 129 kHz/°C for ambient temperature variations. Wireless temperature tracking of a fluid‐flowing channel is experimentally demonstrated using the prototype.

Abstract In multistage decimation filters some stages operate at the low sampling rate, thus reducing the required number of additions per output sample (APOS). State‐of‐the‐art methods for the design of these filters usually consider only two stages. In addition, these methods do not optimize the number of APOS explicitly. This Letter proposes a framework for the design of multistage decimation filters with minimum number of APOS. To accomplish this task, the structures which contain maximum number of stages allowed by specified decimation factor are optimized. As a case study, multistage filters whose stages are cascaded‐integrator‐comb filters are considered. It is illustrated by several examples that the proposed optimum filters ensure smaller number of APOS and higher folding‐band attenuation than those obtained by recent methods for multistage filter design.

Abstract Rydberg‐atom electrometers have the remarkable advantages of self‐calibration and high sensitivity. Based on the classical electromagnetic theory, a localized electric field enhancement structure of a hybrid rectangular resonator (RR) is proposed to improve the sensitivity of quantum microwave measurement. It should be noted that the prototype of the hybrid RR is fabricated and measured at 9.925 GHz. The results of full‐wave simulations show that the uniform and high electric field enhancement in the TE101 fundamental mode is realized. The transient process of resonance is simultaneously simulated, and the time to settle steady state is given as about 104 ns. As indicated through experimental results that the structure can reach 24 dB (enhancement factor of 15.8). As a result, the method proposed in this study, based on atomic measurement capabilities, enables us to improve the measurement sensitivity further and promotes the practical development of quantum microwave measurement technology.

Abstract Most crack‐detection methods adopt a pixel‐level segmentation‐based approach, which requires considerable time and complexity to detect the pixel area of the crack. Unlike a pixel‐level segmentation‐based approach, in this paper, the authors proposed an AugMoCrack network, a bounding box‐level crack detection approach for weakly supervised crack detection achieved by augmenting the training data with Poisson blending, as well as high‐frequency discrete cosine transform‐based features. The proposed AugMoCrack detects the box position of the crack object from a morphological perspective, such as neighbour connectivity within the crack pixels and crack‐area fitting. Based on this perspective, the authors also proposed new morphological attention loss functions for considering the neighbour connectivity and the box area border. Specifically, the authors trained the AugMoCrack network using two datasets and verified its performance based on 591 validation images in the concrete crack dataset and 672 validation images in the Crack500 dataset. Compared with the baseline…

Abstract Techniques to precisely characterise RF components at milli‐Kelvin temperatures support the development of quantum computing systems utilising these components. In this work, an S‐parameter measurement setup to characterise RF integrated circuits at milli‐Kelvin temperatures has been proposed and for the first time, the S‐parameter measurements at milli‐Kelvin temperatures have been validated using two independent calibration techniques, thereby providing more confidence in measurements. The techniques are demonstrated experimentally by comparing and validating calibrated S‐parameter measurements of a cryogenic attenuator integrated circuits at milli‐Kelvin temperatures.