In the design of a microstrip power divider, there are some important factors, including harmonic suppression, insertion loss, and size reduction, which affect the quality of the final product. Thus ...improving each of these factors contributes to a more efficient design. In this respect, a hybrid technique to reduce the size and improve the performance of a Wilkinson power divider (WPD) is introduced in this paper. The proposed method includes a typical series LC circuit, a miniaturizing inductor, and two transmission lines, which make an LC branch. Accordingly, two quarter-wavelength branches of the conventional WPD are replaced by two proposed LC branches. Not only does this modification lead to a 100% size reduction, an infinite number of harmonics suppression, and high-frequency selectivity theoretically, but it also results in a noticeable performance improvement practically compared to using quarter-wavelength branches in the conventional microstrip power dividers. The main important contributions of this technique are extreme size reduction and harmonic suppression for the implementation of a filtering power divider (FPD). Furthermore, by tuning the LC circuit, the arbitrary numbers of unwanted harmonics are blocked while the operating frequency, the stopband bandwidth, and the operating bandwidth are chosen optionally. The experimental result verifies the theoretical and simulated results of the proposed technique and demonstrates its potential for improving the performance and reducing the size of other similar microstrip components.
In this paper, a novel branch-line coupler using meandered line compact microstrip resonant cell (MLCMRC) and bended lines is proposed. The presented coupler works at 0.9 GHz, with good ...specifications. The measured values of S
12
and S
13
at 0.9 GHz are 3.2 dB and 3.3 dB, respectively, which show better than 0.3 dB insertion loss in the pass band. The measured value of S
14
is better than 36 dB and S
11
is better than 31 dB. The proposed design can eliminate 3rd and 5th harmonic with high suppression level (more than 40 dB) and reduce the size of the circuit more than 64% compared to the conventional branch-line coupler. The presented coupler has a very simple structure, which can be used in modern communication applications.
In this paper a miniaturized low pass filter (LPF) with 2.5 GHz cut-off frequency and a novel compact, harmonics suppressed Wilkinson power divider (WPD) at 0.7 GHz is proposed. The proposed divider ...consists of two multi-stub LPFs and three open stubs at each port. The presented open stub at port one suppresses the second harmonic and other two open stubs at output ports, suppress the third harmonic. To suppress high order harmonics a novel 12 sections LPF based on aperiodic stub is proposed. This filter is designed to suppressed 4th to 15th harmonics. The cut off frequency of applied filter is 2.5 GHz, which creates 12 transmission zeros and suppresses corresponding 4th–15th harmonics of the proposed divider. The proposed WPD not only has perfect harmonics suppression, but also extremely decreases the circuit size. The overall size of the fabricated divider is only 0.116 λg × 0.044 λg, which shows more than 73% size reductions, compared to the 0.7 GHz conventional WPD.
In this paper, a novel miniaturized microstrip Wilkinson power divider (WPD) using squared resonators and open-ended stubs is designed, fabricated, and measured. The proposed divider is designed at ...1.9 GHz, which suppresses 2nd, 3rd, and 4th harmonics with high attenuation levels. Moreover, the size of the proposed divider is only 0.1 λ
g
× 0.07 λ
g
, which reduces the circuit size by more than 55%, compared to the conventional Wilkinson divider. In the design process, the neural network model and LC-equivalent circuit model are used to predict the transmission zeros of the circuit. These transmission zeros are used to provide the suppression at the desired harmonics. Also, the main circuit elements could be predicted with the neural network model, which results in a performance improvement of the proposed divider. The results show that the proposed model can predict the frequency response of the designed WPD, accurately.
One of the main problems in scientometrics is to explore the factors that affect the growth of citations in publications to identify best practices of research policy to increase the diffusion of ...scientific research and knowledge in science and society. The principal purpose of this study is to analyze how research funding affects the citation-based performance of scientific output in vital research fields of life science, which is a critical province (area of knowledge) in science to improve the wellbeing of people. This study uses data from the Scopus database in 2015 (to assess the impact on citations in 2021, after more than 5 years) concerning different disciplines of life science, given by “agricultural and biological sciences”, “biochemistry, genetics, and molecular biology”, “Immunology and microbiology”, “neuroscience” and “pharmacology, toxicology and pharmaceutics”. Results demonstrate that although journals publish un-funded articles more than funded publications in all disciplines of life science, the fraction of total citations in funded papers is higher than the share in the total number of publications. In short, funded documents receive more citations than un-funded papers in all research fields of life science under study. Findings also support that citations of total (funded + un-funded), funded, and un-funded published papers have a power-law distribution in all five research fields of life science. Original results here reveal a general property in scientific development: funded research has a higher scaling potential than un-funded publications. Critical implications of research policy, systematized in a decision-making matrix, suggest that R&D investments in “Neuroscience” can generate a positive impact of scientific results in science and society-in terms of citations-higher than other research fields in medicine. Overall, then, results here can explain some characteristics driving scientific change and help policymakers and scholars to allocate resources towards research fields that facilitate the development and diffusion of scientific research and knowledge in life science for positive societal impact.
Scientific developments and new technological trajectories in sensors play an important role in understanding technological and social change. The goal of this study is to develop a scientometric ...analysis (using scientific documents and patents) to explain the evolution of sensor research and new sensor technologies that are critical to science and society. Results suggest that new directions in sensor research are driving technological trajectories of wireless sensor networks, biosensors and wearable sensors. These findings can help scholars to clarify new paths of technological change in sensors and policymakers to allocate research funds towards research fields and sensor technologies that have a high potential of growth for generating a positive societal impact.
The goal of the study here is to model and analyze the relation between research funding and citation-based performance in science to predict the diffusion of new scientific results in society. In ...fact, an important problem in the field of scientometrics is to explain factors determining the growth of citations in documents that can increase the diffusion of scientific results and the impact of science on society. The study here confronts this problem by developing a scientometric analysis to clarify, whenever possible, the relation between research funding and citations of articles in critical disciplines. Data of 2015 retrieved from the Web of Science database relating to the three critical disciplines given by computer science, medicine and economics are analyzed. Results suggest that computer science journals published more funded than unfunded papers. Medicine journals published equally funded and unfunded documents, and finally economics journals published more unfunded than funded papers. In addition, funded documents received more citations than unfunded papers in all three disciplines under study. The study also finds that citations in funded, unfunded and total (funded + unfunded) papers follow a power-law distribution in different disciplines. Another novel finding is that for all disciplines under study, the Matthew effect is greater for funded articles compared to unfunded documents. The results here can support best practices of research policy directed to fund vital scientific research for increasing the diffusion of science and scientific findings in society.
The principal goal of this study is to analyze the evolution of sensor research and technologies from 1990 to 2020 to clarify outlook and future directions. This paper applies network analysis to a ...large dataset of publications concerning sensor research covering a 30-year period. Results show that the evolution of sensors is based on growing scientific interactions within networks, between different research fields that generate co-evolutionary pathways directed to develop general-purpose and/or specialized technologies, such as wireless sensors, biosensors, fiber-optic, and optical sensors, having manifold applications in industries. These results show new directions of sensor research that can drive R&D investments toward promising technological trajectories of sensors, exhibiting a high potential of growth to support scientific, technological, industrial, and socioeconomic development.
In this paper, a new Wilkinson Power Divider (WPD) using open and short stubs is proposed. Open and short stubs are utilized instead of 1/4 wave transmission lines in initial structure to achieve ...harmonics suppression. The proposed WPD is designed for operational frequency of 0.9 GHz and creates 3 transmission zeros at 1.8 GHz, 2.7 GHz and 3.6 GHz, for suppressing second, third and fourth harmonics. The proposed WPD has been fabricated and the measurement results are in good accordance with simulation results. The designed WPD has a 22 % fractional bandwidth with 0.1 dB insertion loss.
COVID-19 outbreak has put the whole world in an unprecedented difficult situation bringing life around the world to a frightening halt and claiming thousands of lives. Due to COVID-19's spread in 212 ...countries and territories and increasing numbers of infected cases and death tolls mounting to 5,212,172 and 334,915 (as of May 22 2020), it remains a real threat to the public health system. This paper renders a response to combat the virus through Artificial Intelligence (AI). Some Deep Learning (DL) methods have been illustrated to reach this goal, including Generative Adversarial Networks (GANs), Extreme Learning Machine (ELM), and Long/Short Term Memory (LSTM). It delineates an integrated bioinformatics approach in which different aspects of information from a continuum of structured and unstructured data sources are put together to form the user-friendly platforms for physicians and researchers. The main advantage of these AI-based platforms is to accelerate the process of diagnosis and treatment of the COVID-19 disease. The most recent related publications and medical reports were investigated with the purpose of choosing inputs and targets of the network that could facilitate reaching a reliable Artificial Neural Network-based tool for challenges associated with COVID-19. Furthermore, there are some specific inputs for each platform, including various forms of the data, such as clinical data and medical imaging which can improve the performance of the introduced approaches toward the best responses in practical applications.
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