Abstract The fabrication of heterojunctions is an intriguing approach to boost the reactivity catalysts. However, facile preparation desirable heterojunction materials remains a challenge. Here, novel CoPS 3 /CoS 2 are created by intuitive phosphatization process on basis structurally flexible cobalt sulfide precursors. Significant stress effect exists at these heterogeneous interfaces, resulting in lattice distortions and exposure more active sites. interface interaction also modifies...

The postmatching topology is an effective approach for broadening the bandwidth of a Doherty power amplifier (DPA). Its efficiency can be enhanced using second-harmonic short-circuit network (SHSN), but at expense bandwidth. In this paper, SHSNs with mutual coupling are proposed to achieve enhancement without sacrificing A broadband was designed and fabricated based on commercially available gallium nitride HEMT (Cree CGH 40006P) devices validate technique. Under continuous-wave excitation,...

This work shows an ultrahigh sensitivity microwave sensor for microfluidic applications. The proposed is made of a microstrip line loaded with complementary splitring resonator (CSRR). meander slot adopted in the CSRR to achieve high field confinement and therefore covered polydimethylsiloxane (PDMS) channel enable strong interaction between liquid sample. complex permittivity sample can be retrieved by variations resonant frequency peak attenuation. design requires very small volume ~0.5 μL...

In this paper, a Doherty power amplifier (DPA) using novel three-port harmonic injection network (HIN) to extend its high-efficiency range is proposed. With the help of part HIN, which placed between carrier and peaking branches, optimal drain fundamental frequency termination for device at back-off saturation can be realized simultaneously thus enhancing efficiency significantly. Meanwhile, HIN also realize second terminations with quasi-open quasi-short circuit current plane, respectively....

This letter introduces a broadband and compact output combiner for Doherty power amplifier (DPA). A grounded quarter Wavelength <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(\lambda/4)$</tex-math></inline-formula> line is added to the of peaking amplifier, which helps compensate bandwidth limiting effect that happens in conventional combiner. Frequency response analysis indicates stable impedance...

A novel beam-steering reconfigurable substrate integrated waveguide (SIW) horn antenna is presented. By employing p-i-n diodes as tuning mechanisms, the states of copper posts SIW can be electronically controlled. Accordingly, aperture direction switched, and a 360° beam-scanning ability realized. pair bowl-shaped reflectors introduced for achieving wide impedance bandwidth good directional radiation patterns. fully functional prototype with 26.2% developed tested, demonstrating measured...

This letter presents a novel high efficiency power amplifier (PA) with good bandpass responses. By designing filter (BPF) different load impedances to meet the requirement of PA, responses can be exhibited. Compared classical cascaded PA and filter, total size proposed design is greatly reduced. Meanwhile, bandwidth extended. Two transmission zeros are generated at passband edges, resulting in selectivity. For demonstration, filter-integrated prototype implemented. Both theoretical analysis...

A new, dynamic behavioral modeling technique, based on a time-delay support vector regression (SVR) method, is presented in this paper. As an advanced machine learning algorithm, the SVR method provides effective option for of radio frequency (RF) power amplifiers (PAs), taking into account effects both device nonlinearity and memory. The basic theory proposed technique given, along with detailed model extraction procedure. Unlike traditional artificial neural network (ANN) techniques, which...

A planar periodic leaky-wave antenna (PLWA) with continuous backward-to-forward beam-scanning capability and consistent gain is presented. The PLWA made of a new type periodically arranging meander line structures, in which the capacitive coupling between neighboring units plays key role achieving high scanning rate. In detail, rate proposed efficiently tuned by varying gap two adjacent units, without considerably changing working frequency band. To mitigate open stopband (OSB) to improve...

A novel bandpass frequency-selective surface (FSS) with high selectivity and angular stability is presented. In the skirts of narrow passband, two transmission zeros (TZs) are generated, leading to steep roll-offs at both left right skirts. The realization TZs using a single piece printed circuit board facilitates fabrication. current distribution equivalent model given illustrate generation mechanism TZs. proposed FSS can achieve good stabilities polarization angle. size this...

In this letter, an ultrahigh sensitivity microwave microfluidic sensor is proposed to retrieve the dielectric properties of a liquid sample. Two metal strips in ground plane defect are connected microstrip line through metallic vias. An interdigital capacitor (IDC) structure introduced between produce strong electric field confinement, so that loaded sample can fully interact with field. The complex permittivity affects magnitude frequency offset and peak attenuation, thereby establishing...

This letter presents a novel harmonic control circuit (HCC) for class-F power amplifiers (PAs). A compact microstrip resonant cell (CMRC) is inserted between the transistor and output fundamental matching network. Third open condition size reduction are achieved simultaneously. scheme provides straightforward simple approach to design HCC. PA designed fabricated demonstration. The measured maximum power-added efficiency (PAE) 74% with 10 dB gain near 1 compression point.

In this paper, a new load modulation network (LMN) is proposed for the Doherty power amplifier (DPA). By adjusting transmission line characteristic impedances in LMN, efficiency degradation due to incomplete caused by current unbalance between sub-amplifiers can be alleviated. Comprehensive theoretical analysis conducted investigate impact of imperfect profile on overall and give rise judicious solution. To validate theory, two DPA prototypes based GaAs pseudomorphic HEMTs are implemented...

In this communication, an odd and even mode compression method is proposed to extend the bandwidth of conventional thin dipole antennas while maintaining a stable omnidirectional radiation pattern. Wide achieved by simultaneously exciting compressing 1<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup>-order (odd) 2<sup xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup>-order (even) modes, enabling their combination. The offset-fed used...

Measuring the electromagnetic properties of materials has important applications in many fields. In this paper, two electrically small sensors based on split ring resonators (SRRs) with extended long legs, i.e., two-layer and three-layer magnetic coupled SRRs, are proposed to measure permittivity samples unknown materials. By virtue characteristics have several merits, such as extremely compact size ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML"...

In this paper, a high-sensitive microwave dielectric sensor targeted for material permittivity characterization is proposed. A reflective voltage controlled oscillator devised by virtue of the compact microstrip resonant cell (CMRC) and embedded into fractional-N phase-locked loop frequency synthesizer. The CMRC structure, covered with under test, changes its resonating characteristics and, hence, initial oscillating frequency. Due to presence synthesizer, shift finally translated...

A new, frequency-domain, behavioral modeling methodology for gallium nitride (GaN) high-electron-mobility transistors (HEMTs), based on the Bayesian inference theory, is presented in this paper. Several different probability distribution (kernel) functions are examined Bayesian-based architecture, with optimal kernel function identified through experimental testing. These results compared to an alternative approach artificial neural networks (ANNs), data showing that proposed demonstrates...

In a conventional Doherty Power Amplifier (DPA), harmonic isolation is typically required between the two transistors to prevent them from modulating each other at frequencies. Normally, current clipped saturation, which results in poor in-band non-linearity, e.g. IMD3. Hence, mutual interaction desirable when properly used clipping active devices, thus improving linearity. this paper, for first time, linearity enhancement technique Doherty-like power amplifier (DLPA) based on presented. The...