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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 S12 and S13 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 S14 is better than 36 dB and S11 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.

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 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.

This paper presents a theoretical design strategy for an ultra-small diplexer optimized for fifth-generation (5G) communication systems. The diplexer design includes a dual-band band-pass filter comprising coupled lines, transmission lines (TLs), and two proposed resonators. These resonator configurations are analyzed for enhanced optimization and structural clarity. Even and odd mode analysis, along with the examination of the LC equivalent circuit, is used to determine the TL parameters. The proposed diplexer operates effectively across four 5G mid-range frequency bands, enabled by the proposed band-pass filter. It functions at 1.08, 1.17, 2, and 2.18 GHz, achieving S 21 values of −1.18, −1.24, −1.24, and − 1.37 dB, respectively, at these frequencies. The final power amplifier circuit benefits from the described diplexer due to its compact size (8.1 mm × 19.4 mm). The proposed power amplifier demonstrates operation at these frequencies of 1.08, 1.17, 2, and 2.18 GHz with a power-added efficiency (PAE) of approximately 63% and a drain efficiency (DE) of about 64%. These results show the proper performance of the proposed diplexer and power amplifier for mid-band 5G applications.

This research presents a new design and fabrication of a quadrature hybrid coupler using π-shaped lumped elements. The proposed π-shaped elements have resulted in ultra-size reduction and harmonic suppression ability simultaneously. The proposed coupler correctly works at 800 MHz, the insertion loss is less than 0.15 dB and more than 26 dB, isolation and return loss are obtained at the operating frequency. The size of the proposed coupler is only 12.8 mm ×12.2 mm, which is equal to 0.046 λg × 0.044 λg, where λg is of the guided-wavelength at 800 MHz. The conventional coupler has a large size of 0.25 λg × 0.25 λg, which is equal to 68.5 mm × 68.5 mm. The proposed coupler provides about 96% size reduction compared to the conventional coupler. Moreover, the proposed quadrature hybrid coupler has wide harmonic suppression from 2.1 GHz to 10 GHz.

This paper presents a novel approach to reducing undesirable coupling in antenna arrays using custom-designed resonators and inverse surrogate modeling. To illustrate the concept, two standard patch antenna cells with 0.07λ edge-to-edge distance were designed and fabricated to operate at 2.45 GHz. A stepped-impedance resonator was applied between the antennas to suppress their mutual coupling. For the first time, the optimum values of the resonator geometry parameters were obtained using the proposed inverse artificial neural network (ANN) model, constructed from the sampled EM-simulation data of the system, and trained using the particle swarm optimization (PSO) algorithm. The inverse ANN surrogate directly yields the optimum resonator dimensions based on the target values of its S-parameters being the input parameters of the model. The involvement of surrogate modeling also contributes to the acceleration of the design process, as the array does not need to undergo direct EM-driven optimization. The obtained results indicate a remarkable cancellation of the surface currents between two antennas at their operating frequency, which translates into isolation as high as −46.2 dB at 2.45 GHz, corresponding to over 37 dB improvement as compared to the conventional setup.

Conventional Wilkinson power dividers (WPDs) perform satisfactorily near the intended operation frequency. Nonetheless, these WPDs demonstrate subpar performance in the stopband and necessitate a significant physical space. To enhance the existing level of advancement and in order to improve on the current state-of-the-art, a modified WPD is designed and fabricated, demonstrating a significant improvement in stopband and superior isolation between output ports. To improve the stopband and suppress unwanted harmonics, a low-pass filter (LPF) structure is placed in the both branches of the conventional WPD. The proposed modified WPD depicts a wide stopband bandwidth ( f SB  > 17.25 GHz) from 2.75 to over 20 GHz with an attenuation level of 20 dB, suppressing 2nd to 11th harmonics . According to measured results, the input return loss (|S 11 |), insertion loss (|S 21 |) and output isolation (|S 32 |) at f  = 1.8 GHz are better than 33 dB, 3.2 dB and 21 dB, respectively. Indeed, the proposed modified WPD exhibits a magnitude imbalance of 0.00018, a phase imbalance of 1.25 degrees and a group delay of 0.5 ns. The proposed WPD depicts a compact size of 35 mm × 25 mm (0.38 λg × 0.27 λg), where λg is the guided wavelength at f  = 1.8 GHz. There is a good agreement between the simulated and measured results. According to the obtained results, the proposed modified WPD shows a desirable performance for modern LTE and GSM communication applications.

NOABSTRACTThe goal of this study is to analyze the relationship between funded and unfunded papers and their citations in both basic and applied sciences.A power law model analyzes the relationship between research funding and citations of papers using 831,337 documents recorded in the Web of Science database.The original results reveal general characteristics of the diffusion of science in research fields: a) Funded articles receive higher citations compared to unfunded papers in journals; b) Funded articles exhibit a super-linear growth in citations, surpassing the increase seen in unfunded articles. This finding reveals a higher diffusion of scientific knowledge in funded articles. Moreover, c) funded articles in both basic and applied sciences demonstrate a similar expected change in citations, equivalent to about 1.23%, when the number of funded papers increases by 1% in journals. This result suggests, for the first time, that funding effect of scientific research is an invariant driver, irrespective of the nature of the basic or applied sciences.This evidence suggests empirical laws of funding for scientific citations that explain the importance of robust funding mechanisms for achieving impactful research outcomes in science and society. These findings here also highlight that funding for scientific research is a critical driving force in supporting citations and the dissemination of scientific knowledge in recorded documents in both basic and applied sciences.This comprehensive result provides a holistic view of the relationship between funding and citation performance in science to guide policymakers and R&D managers with science policies by directing funding to research in promoting the scientific development and higher diffusion of results for the progress of human society.