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Special Issue "Advanced RF, Microwave Engineering, and High-Power Microwave Sources"

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A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Microwave and Wireless Communications".

Deadline for manuscript submissions: 30 April 2024 | Viewed by 10116

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Special Issue Editors

Dr. Sohail Mumtaz

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Guest Editor

Electrical and Biological Physics, Kwangwoon University, Seoul 01897, Korea
Interests: high power microwaves; virtual cathode oscillator; particle-in-cell simulation; basic plasma diagnostics; nonthermal plasma; reactive species; microwave biological interaction; radiation biology; efficiency improvement of microwave sources; pulse power sources; gyrotrons, magnetrons, klystrons, backward wave oscillators, vacuum tubes; RF antenna; terahertz sources; metamaterials; intense relativistic electron beams; millimeter-waves; vircators; power beaming; ultra-wide band; microwave emission modes

Dr. Syed Muzahir Abbas

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Guest Editor

Electrical and Electronic Engineering, Macquarie University, Macquarie Park, NSW 2109, Australia
Interests: antennas; electromagnetics; carbon nanotubes; wearable; 3d printing; high-impedance surfaces; frequency-selective surfaces; 5G; mmWave; millimeter wave; PDMS; high gain; base station; UHF; VHF; beam steering
Special Issues, Collections and Topics in MDPI journals

Dr. Pradeep Lamichhane

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Guest Editor

School of Engineering, Warwick University, Coventry CV4 7AL, UK
Interests: microwave; microwave plasma; nonthermal plasma; nitrogen fixation; plasma source designing; plasma agriculture; plasma diagnostics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microwaves are a form of non-ionizing radiation with wavelengths and frequencies ranging from 1m to 1 mm and 300 MHz to 300 GHz, respectively. RF/microwave systems are essential in all current wireless communication and a wide range of applications such as industries, military, households, accelerators, communication, astronomy, spectroscopy, and the medical profession. It is not an overstatement to say that RF/microwave technologies impact every area of our lives; they are everywhere, from the wireless doorbell to keyless entrance into our automobiles, from cooking to industrial heating, from cell phones to computer systems, and from medical to space technology. This massive penetration of RF/microwave systems in our modern life has been facilitated by large and quick technical advancements at many levels. If the microwave power exceeds the peak power of 100 MW it is known as high power microwave (HPM). Developing high-power microwave technology might help with a variety of applications, including space and satellite missions, increasing the detection range of radar technology, communication systems, power beaming, linear collider, fusion heating, electronic warfare, and serving as a nonlethal weapon in military use. Unfortunately, the majority of HPM sources generate microwaves with low device efficiency, which is why boosting efficiency is an ongoing subject of research in this issue.

This Special Issue of the MDPI journal Electronics entitled "Advanced RF, Microwave engineering, and high-power microwave sources" invites innovative papers, with a particular emphasis on current advances in the analysis, design, implementation, designing, and measurement of RF and microwave circuits and sources. A wide range of studies based on RF, microwave, and wireless technologies, such as RF transceivers, power dividers/combiners, antennas, wireless power transfer, energy harvesting, high power microwave generation, particle-in-cell simulation, microwave mode analysis, RF plasma, pulsed power technologies, vacuum tubes, millimeter-waves, terahertz sources, and so on, are of interest of this issue. Authors are encouraged to submit both regular research articles and well-written review articles.

Dr. Sohail Mumtaz
Dr. Syed Muzahir Abbas
Dr. Pradeep Lamichhane
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Electronics is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

radio frequency
microwave generation
pulsed power technology
virtual cathode oscillators
particle-in-cell simulation
microwave sources
RF plasma
RF circuits
microwave imaging
device efficiency
vacuum tubes
RF antenna
terahertz sources
millimeter-waves
metamaterials
magnetic mirror
intense relativistic electron beams

Published Papers (10 papers)

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Research

Open AccessArticle

A Novel High-Power Rotary Waveguide Phase Shifter Based on Circular Polarizers

and

Electronics 2023, 12(13), 2963; https://doi.org/10.3390/electronics12132963 - 05 Jul 2023

Viewed by 426

Abstract

This paper presents a novel high-power rotary waveguide phase shifter based on circular polarizers specifically engineered for high-power microwave (HPM) applications. The phase shifter is capable of performing a precise 360° linear phase shift through rotation and consists of three parts: a linearly polarized to left-handed circularly polarized (LP-LHCP) mode converter, a left-handed to right-handed circularly polarized (LH-RHCP) mode converter, and a linearly polarized to right-handed circularly polarized (LP-RHCP) mode converter. This paper analyzes the phase-shifting principle, optimizes the three parts of the X-band rotary waveguide phase shifter, and conducts simulation studies on the entire phase shifter, which is made of aluminum. The results show that the reflection is less than −20 dB and the insertion loss is below 0.3 dB within 9.5 GHz to 10.2 GHz. The phase shift is equal to twice the rotation angle within this frequency range. Specifically, the phase shifter can achieve a linear phase shift of 360° when rotated from 0° to 180°, with a maximum deviation of less than 1.2°. Moreover, the power-handling capacity of the phase shifter in vacuum exceeds 242 MW. In the meantime, a prototype of a phase shifter was manufactured, and the experimental results are in good agreement with the simulation results. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

A Comprehensive Overview of the Temperature-Dependent Modeling of the High-Power GaN HEMT Technology Using mm-Wave Scattering Parameter Measurements

and

Electronics 2023, 12(8), 1771; https://doi.org/10.3390/electronics12081771 - 08 Apr 2023

Cited by 2 | Viewed by 1058

Abstract

The gallium-nitride (GaN) high electron-mobility transistor (HEMT) technology has emerged as an attractive candidate for high-frequency, high-power, and high-temperature applications due to the unique physical characteristics of the GaN material. Over the years, much effort has been spent on measurement-based modeling since accurate models are essential for allowing the use of this advanced transistor technology at its best. The present analysis is focused on the modeling of the scattering (S-) parameter measurements for a 0.25 μm GaN HEMT on silicon carbide (SiC) substrate at extreme operating conditions: a large gate width (i.e., the transistor is based on an interdigitated layout consisting of ten fingers, each with a length of 150 μm, resulting in a total gate periphery of 1.5 mm), a high ambient temperature (i.e., from 35 °C up to 200 °C with a step of 55 °C), a high dissipated power (i.e., 5.1 W at 35 °C), and a high frequency in the millimeter-wave range (i.e., from 200 MHz up to 65 GHz with a step of 200 MHz). Three different modeling approaches are investigated: the equivalent-circuit model, artificial neural networks (ANNs), and gated recurrent units (GRUs). As is shown, each modeling approach has its pros and cons that need to be considered, depending on the target performance and their specifications. This implies that an appropriate selection of the transistor modeling approach should be based on discerning and prioritizing the key features that are indeed the most important for a given application. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Experimental Study of RF–Plasma Interaction Using a Low-Pressure DC Glow Discharge Tube for MPC

Asif Mehmood Khan

Muhammad Mansoor Ahmed

and

Umair Rafique

Electronics 2023, 12(3), 551; https://doi.org/10.3390/electronics12030551 - 20 Jan 2023

Viewed by 1169

Abstract

This paper aims to perform experimental validation of RF–plasma interaction behaviors for the purposes of wave transmission and reflection. Wave reflection from plasma is of interest as it finds applications in pulse compression and RF polarizer-based systems. Simulations are performed using a combination of Magic3D and COMSOL multiphysics to characterize the plasma–wave interaction and discharge tube properties. The goal is to generate plasma with characteristics that wholly reflect the incident electromagnetic wave. A glass tube of inner diameter 22 mm and length 100 mm, with 12 mm brass electrodes, is fabricated for plasma generation. Argon-based DC glow discharge is sustained at 500 volts at a pressure of 3.8 Torr. Plasma density is calculated to be

2.529 \times 10^{19}

^{- 3}

, with a corresponding plasma frequency of 7.18 GHz. Due to this higher frequency, a 3 GHz incident RF wave is reflected, as measured through S-parameter measurements using a network analyzer. Off and on states of the tube correspond to

S_{11} = - 40

dB and

S_{11} = - 13

dB, which show wave transmission and reflection, respectively. When the plasma column is ignited, the reflected wave has a phase difference of

180^{\circ}

. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Magnetic Field Testing Technique of System-Generated Electromagnetic Pulse Based on Magnetoresistance Effects

and

Electronics 2023, 12(3), 492; https://doi.org/10.3390/electronics12030492 - 17 Jan 2023

Cited by 1 | Viewed by 872

Abstract

To address the technical challenges of system-generated electromagnetic pulse (SGEMP) measurement, the generation environment of SGEMP is introduced, and the characteristics of the magnetic field waveform to be measured are analyzed first in this paper. Then a magnetoresistance-based SGEMP measurement method is proposed for the first time. Aiming at the problem that the high frequency response of the existing commercial magnetoresistance chips cannot meet the test requirements, a pulsed magnetic field detector with strong anti-interference ability is developed in this work based on the tunneling magnetoresistance (TMR) sensor chip developed by Lanzhou University and a high-gain amplifier circuit with common mode rejection and a good shielding structure. It can be shown from the calibration results that the detector sensitivity factor is 4.0 nT/mV and the measurable pulse front is greater than or equal to 28 ns, which meet the requirements of SGEMP magnetic field waveform measurement. Based on the developed detector, the ideal test waveform is obtained under the “Flash II” hard X-ray pulse source through a reasonable experimental design. The related work has laid a foundation for validating the numerical calculation model and further mastering the propagation law and effect mechanism of SGEMP. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

A CC-Type IPT System Based on S/S/N Three-Coil Structure to Realize Low-Cost and Compact Receiver

and

Electronics 2023, 12(2), 463; https://doi.org/10.3390/electronics12020463 - 16 Jan 2023

Viewed by 841

Abstract

The characteristics of load-independent constant current (CC) output and zero phase angle (ZPA) operation are required in many scenarios of inductive power transfer (IPT) applications. However, the existing topologies with CC output characteristics usually need to introduce additional compensation components on the receiving side to compensate for reactive power and achieve the preset function. This not only increases the occupied space of the receiving side, but also increases the cost and weight. Therefore, this study proposes a new IPT system based on an S/S/N three-coil structure. The proposed system can achieve the CC output function and an operation nearly ZPA and zero-voltage switching (ZVS) through flexible parameter design. Moreover, there are no compensation components on the receiving side of the proposed system, which guarantees a low-cost, lightweight, and compact receiver. Firstly, a comprehensive analysis of the proposed S/S/N three-coil structure IPT system that implements CC output characteristics and ZPA operation is provided. Then, the conditions for realizing ZVS are discussed in terms of parameter design and the sensitivity of CC output characteristics to the changes in compensation capacitance parameters. Furthermore, the proposed S/S/N three-coil structure IPT system is compared with previous related studies to reflect its advantages. Finally, the correctness of the theory is verified by simulation and experiment. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Calculation and Analysis of Characteristic Parameters for Lossy Resonator

Jian Cui

Yu Yu

and

Yuanyao Lu

Electronics 2023, 12(1), 7; https://doi.org/10.3390/electronics12010007 - 20 Dec 2022

Cited by 1 | Viewed by 808

Abstract

Resonator is widely employed in microwave and millimeter-wave fields. However, it is challenging and crucial to calculate the electromagnetic field distribution in the resonant cavity with various loss dielectrics. In this paper, according to the axisymmetric distribution characteristics of the lossy resonator, the electromagnetic function of each part in the cavity is established with the Borgnis function, the characteristic equation is obtained based on the mode-matching method, and the resonance frequency and Q factor of the eigenmode TM₀₁₀ are numerically calculated. With the proposed method, the impact of various dielectric structures and characteristics parameters on the resonant properties of the TM₀₁₀ mode may be thoroughly examined by taking into account the influence of the thickness as well as the materials of the lossy layer in the z direction. The relative error between the theoretical and the simulated results is below 0.7% at different structures and lossy dielectrics, which indicates that the general calculation approach, as well as crucial data and structure references, is suitable for a related device design in TM₀₁₀ mode. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Reduced-Cost Optimization-Based Miniaturization of Microwave Passives by Multi-Resolution EM Simulations for Internet of Things and Space-Limited Applications

Anna Pietrenko-Dabrowska

Slawomir Koziel

and

Ali Ghaffarlouy Raef

Electronics 2022, 11(24), 4094; https://doi.org/10.3390/electronics11244094 - 08 Dec 2022

Cited by 1 | Viewed by 703

Abstract

Stringent performance specifications along with constraints imposed on physical dimensions make the design of contemporary microwave components a truly onerous task. In recent years, the latter demand has been growing in importance with the innovative application of areas such as the Internet of Things coming into play. The need to employ full-wave electromagnetic (EM) simulations for response evaluation, reliable, yet CPU-heavy, only aggravates the issue. This paper proposes a reduced-cost miniaturization algorithm that employs a trust-region search procedure and multi-resolution EM simulations. In our approach, the resolution of the EM model is adjusted throughout the optimization process based on its convergence status starting from the lowest admissible fidelity. As the algorithm converges, the resolution is increased up to the high-fidelity one, used at the final phase to ensure reliability. Four microwave components have been utilized as verification structures: an impedance matching transformer and three branch-line couplers. Significant savings in terms of the number of EM analyses required to conclude the size reduction process of 41, 42, 38 and 50 percent have been obtained (in comparison to a single-fidelity procedure). The footprint area of the designs optimized using the proposed approach are equal to 32, 205, 410 and 132 mm², in comparison to 52, 275, 525 and 213 mm² of the initial (and already compact) design. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

The Characteristics of the Second and Third Virtual Cathodes in an Axial Vircator for the Generation of High-Power Microwaves

Sohail Mumtaz

and

Eun-Ha Choi

Electronics 2022, 11(23), 3973; https://doi.org/10.3390/electronics11233973 - 30 Nov 2022

Cited by 2 | Viewed by 1187

Abstract

A virtual cathode oscillator or vircator is a vacuum tube for producing high-power microwaves (HPM). The efficiency of the vircator has been a difficult task for decades. The main reasons for low efficiency are intense relativistic electron beam (IREB) loss and few or no interactions between IREB and HPM. In this case, forming multiple virtual cathodes may be beneficial in overcoming these constraints. By reusing the axially propagating leaked electrons (LE), we could confine them and form multiple virtual cathodes (VCs). This article discussed the characteristics of newly formed VCs based on simulation results. The formation time of new VCs was discovered to be highly dependent on the reflector position and the density of LE approaching their surfaces. Furthermore, multiple VC formation in the waveguide region does not affect conventional VCs’ position or forming time. The emission mode of the generated HPM was TM₀₁ with single and multiple VCs and remained unaffected. The formation of multiple VCs positively influenced the axial and radial electric fields. When compared to a single VC, the axial and radial electric field increased 25.5 and 18 times with multiple VCs. The findings suggested that forming multiple VCs could be a future hope for achieving high vircator efficiency. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Design of the Radio Frequency Section of a Ka-Band Multiple Beam Ladder-Type Extended Interaction Klystron

Santigopal Maity

Madutha Santosh Kumar

Chaitali Koley

Debashish Pal

and

Ayan Kumar Bandyopadhyay

Electronics 2022, 11(22), 3781; https://doi.org/10.3390/electronics11223781 - 17 Nov 2022

Viewed by 1059

Abstract

Ka-band frequencies are becoming increasingly popular due to their application potential in high-data-rate wireless communications relevant to 5G applications, satellite link establishment, etc. High-power amplifiers in this frequency band, offering several tens of watts of output RF power, are one of the main enabling components of these communication systems. This article reports the design studies and analysis of the radio frequency (RF) section of a multiple beam-extended interaction klystron (MB-EIK). The proposed multiple beam RF section with a ladder-type EIK structure offers several crucial features, such as a low-voltage operation, moderate operational bandwidth, and high output power. Starting from the design of the intermediate cavities, the input and output sections and the overall RF section are presented. The proposed RF section supports the operation at 28.5 GHz center frequency with about a 500 MHz 3 dB bandwidth employing four electron beams with a 4 kV DC accelerating field. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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Open AccessArticle

Electrical Characterization of Through-Silicon-via-Based Coaxial Line for High-Frequency 3D Integration (Invited Paper)

and

Electronics 2022, 11(20), 3417; https://doi.org/10.3390/electronics11203417 - 21 Oct 2022

Viewed by 1050

Abstract

Through-silicon-via (TSV)-based coaxial line techniques can reduce the high-frequency loss due to the low resistivity in the silicon substrate and thus can improve the efficiency of vertical signal transmission. Moreover, a TSV-based coaxial structure allows easily realizing the impedance matching in RF/microwave systems for excellent electrical performance. However, due to the limitations of existing available dielectric materials and the difficulties and challenges in the manufacturing process, ideal coaxial TSVs are not easy to obtain, and thus, the achieved electrical performance might be unexpected. In order to increase the flexibility of designing and manufacturing TSV-based coaxial structures and to better evaluate the fabricated devices, modeling and analysis theories of the corresponding high-frequency electrical performance are proposed in the paper. The theories are finally well validated using the finite-element simulation results, hereby providing guiding rules for selecting materials and improving manufacturing techniques in the practical process, so as to optimize the high-frequency performance of the TSV structures. Full article

(This article belongs to the Special Issue Advanced RF, Microwave Engineering, and High-Power Microwave Sources)

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