In this paper, a new neuro-based approach using a feed-forward neural network is presented to design a Wilkinson power divider. The proposed power divider is composed of symmetrical modified T-shaped resonators, which are a replacement for quarter-wave transmission lines in the conventional structure.The proposed technique reduces the size of the power divider by 45% and suppresses unwanted bands up to the fifth harmonics. To verify the concept, a prototype of the power divider has been fabricated and tested, exhibiting good agreement between the predicted and measured results. The results show that the insertion loss and the isolation at the center frequency are about 3.3 ± 0.1 dB and 23 dB, respectively. K E Y W O R D Sartificial intelligence, couplers, evolutionary optimization, harmonic suppression, lumpedequivalent circuit, microstrip technology, neural network, Wilkinson power divider

No abstract

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.‎

The spread of SARS-CoV-2 can be considered one of the most complicated patterns with a large number of uncertainties and nonlinearities. Therefore, analysis and prediction of the distribution of this virus are one of the most challenging problems, affecting the planning and managing of its impacts. Although different vaccines and drugs have been proved, produced, and distributed one after another, several new fast-spreading SARS-CoV-2 variants have been detected. This is why numerous techniques based on artificial intelligence (AI) have been recently designed or redeveloped to forecast these variants more effectively. The focus of such methods is on deep learning (DL) and machine learning (ML), and they can forecast nonlinear trends in epidemiological issues appropriately. This short review aims to summarize and evaluate the trustworthiness and performance of some important AI-empowered approaches used for the prediction of the spread of COVID-19. Sixty-five preprints, peer-reviewed papers, conference proceedings, and book chapters published in 2020 were reviewed. Our criteria to include or exclude references were the performance of these methods reported in the documents. The results revealed that although methods under discussion in this review have suitable potential to predict the spread of COVID-19, there are still weaknesses and drawbacks that fall in the domain of future research and scientific endeavors.

An ultra-wideband (UWB) bandpass filter with ultra-wide stopband based on a rectangular ring resonator is presented. The filter is designed for the operational frequency band from 4.10 GHz to 10.80 GHz with an ultra-wide stopband from 11.23 GHz to 40 GHz. The even and odd equivalent circuits are used to achieve a suitable analysis of the proposed filter performance. To verify the design and analysis, the proposed bandpass filter is simulated using full-wave EM simulator Advanced Design System and fabricated on a 20mil thick Rogers_RO4003 substrate with relative permittivity of 3.38 and a loss tangent of 0.0021. The proposed filter behavior is investigated and simulation results are in good agreement with measurement results.

A compact microstrip low-pass filter (LPF) with ultra-wide stopband using the analysed triangular-shaped resonator is presented. To achieve LC equivalent circuit of the triangular-shaped resonator, the structure of a rectangular-shaped resonator is adopted. To investigate the behaviour of the proposed triangular-shaped resonator, transfer function of the main triangular resonator is calculated. The designed LPF has −3 dB cutoff frequency of 1.52 GHz with the stopband bandwidth around 12fc and total circuit size of 0.062λ g × 0.104λ g. The proposed LPF has the figure of merit of 46,718, which shows its good performance. The proposed filter is designed, simulated and fabricated. It is observed that the measurement results are well matched with simulation results.

A new microstrip lowpass filter with sharp roll-off and high suppression level in stop-band is presented. To achieve the lowpass filter with high performance, coupled T-shaped, elliptical and radial resonators are adopted. New formulas for calculating

This paper presents a new Doherty power amplifier (DPA) with harmonics suppression. A Wilkinson power divider (WPD) with open-ended and short-ended stubs is designed to suppress unwanted signals. To design the power divider in the circuit of the DPA, even and odd mode analyses are utilized. The proposed design operates at range of 1.2–1.6 GHz. The linearity of the suggested DPA is increased about 6 dBm, in comparison with the main amplifier. The designed Doherty amplifier has a power added efficiency (PAE), drain efficiency (DE) and Gain about 60, 61% and 19 dB, respectively. The designed WPD suppresses 2nd up to 14th harmonics with more than 20 dB suppression level, which is useful for suppressing unwanted harmonics in DPA design. ATF-34143 transistors (pHEMT technology) are used for this DPA amplifier design. The main amplifier has class-F topology and class-F inverse topology is used for auxiliary amplifier.