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This paper presents a novel wideband antenna with a simple structure comprising an integrated microstrip patch antenna (MPA) and three shorted microstrip patch antennas (SMPAs). These four radiators constitute an antenna that operates under quad resonances and achieves a wide frequency bandwidth. Since all units are electrically connected, the antenna can be easily fabricated by folding a single metallic strip to realize an all-metal antenna structure, leading to enhanced resistance to extreme environmental conditions and lower power loss. An antenna prototype was used to validate the proposed concept. The measurement results indicated that the proposed handmade structure, which employed probe excitation with overall electrical dimensions of 0.29λ × 0.27λ × 0.11λ, can acquire an impedance frequency bandwidth of 67% for S11 = -10 dB from 1.6-3.2 GHz and achieve a maximum boresight gain of up to 10 dB. The wide frequency bandwidth, high gain, and simple structure make this antenna a promising candidate for wideband mobile systems. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper starts with the proposal of an enhanced version of a planar rectangular slot antenna fed by the quasi‐TEM printed ridge gap waveguide (PRGW), attended with a numerical study of a miniaturization procedure showing the limitations of the conventional PRGW‐based antennas. Then innovative solution is introducing a new miniaturized pure TEM wide‐band slot antenna utilizing double PRGW (D‐PRGW) technology; the proposed approach is self‐packaged and shows high potential for enhancing antenna performance, particularly in terms of bandwidth, gain, and compactness. This technology is featured with low loss, high performance, and compact size; it consists of surrounding the ridge area with a double layer of electromagnetic band gap (EBG) lattice instead of one to eliminate the surface waves effectively and keep the signal completely confined inside the ridge area with strict minimum rows of EBG. Therefore, a broad impedance matching bandwidth (|S11| ≤ −10 dB) of 33.33% is obtained from 50 to 70 GHz, which covers the unlicensed NR parts (n262; amp; n263) of the V band. Furthermore, the antenna achieves a peak gain of approximately 16 at 65 GHz while the overall efficiency remains above 90% across the entire operating frequency band. The high performance along with the compact size of this novel design makes it a good candidate for 5G wireless communications applications centered around 60 GHz. [ABSTRACT FROM AUTHOR]

Purpose: Piezoelectric materials, when positioned angularly with respect to their crystallographic axis, exhibit a fascinating phenomenon: the creation of a frequency phase shift (FPS) during resonance. Traditionally, FPS arises due to changes in shape and material properties, causing the resonance frequency point to shift. However, present research has revealed an unexplored avenue: when a piezoelectric crystal vibrates along an axis that deviates from the normal poling axis, it manifests FPS phenomena. This unique behavior can be harnessed for a wide-bandwidth energy harvester—a novel application that has not been investigated by other researchers. Methods: Rather than delving into the theoretical nature of FPS, this study focuses on practical implementation of this phenomenon. Clear mathematical assumptions, coupled with experimental validation, confirm the significant impact of angular position on piezoelectric crystals. Overall, 3 methods of mathematical modeling (with explicit formulas in the appendix), experimental setup and finite element method (FEM) have been used in this study. Results and Conclusions: The results from all the three methods for solving flexural motion demonstrate how power output depends on the angular position of the model and the dimensional variations of the beam and the piezoelectric material. The newly designed energy harvester produces 5 μWatt of power in both analytical and experimental approaches, under an acceleration of 1 m s - 2 . Operating within a 20 Hz bandwidth for half-power level and utilizing two perpendicular beams, this design ensures that power output remains nonzero regardless of changes in the assembly's direction of excitation. [ABSTRACT FROM AUTHOR]

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new decoupling element technology is used to create a tiny circular patch mutiple input multiple output (MIMO) antenna measuring 20 × 25 × 1.6 mm3. A simple split‐ring resonator (SRR) metamaterial design with adjustable inner ring inductance and capacitance allows MIMO antennas to operate across several frequency bands. Tunable‐split ring resonators (T‐SRRs) are small and improve antenna element isolation. The proposed MIMO system provides isolation larger than 20 dB from 5.93 to 12.63 GHz. It is useful for radar applications since it includes the C‐band upper link (5.925–6.425 GHz) and the X‐band (8–12 GHz). With good tuning and network structure decoupling, antennas can operate in dual bands with isolation levels below −15 dB. Over 85% radiation efficiency and 72% miniaturization were achieved in the proposed MIMO antenna. The antenna has good radiation and diversity performance, including an envelope correlation coefficient < 0.1 and a diversity gain of 9.98 dB. These qualities make it suitable for advanced technology. [ABSTRACT FROM AUTHOR]

In this paper, a CGH40010F GaN-based wideband RF rectifier with high rectification efficiency is presented. A novel continuous class-EFJ-mode rectifier is constructed by combining a continuous class-J-mode rectifier and class-EF-mode rectifier under specific impedance conditions. This novel continuous class-EFJ-mode rectifier has high rectification efficiency and wide bandwidth at the same time. For validation, a wideband high-efficiency class-EFJ-mode rectifier functioning within the 2.0–3.0 GHz range is designed, fabricated, and measured. The measurements indicate that, with an input power of 40 dBm and a resistance of 72 Ω on the dc load, the implemented rectifier sustains a rectification efficiency exceeding 60% across its entire operational frequency band. Meanwhile, the dimensions of the circuits are only 3 cm × 3.1 cm. [ABSTRACT FROM AUTHOR]

This work presents the study of effect of morphology of carbonyl iron, carbonyl iron-based, and e-waste-based mixtures on microwave absorption properties. Firstly, the flake shaped carbonyl iron particles and its mixture are prepared using conventional and efficient ball milling and blending method, respectively. It provides the absorption in lower frequency region. Further, the covered frequency range starts to shifts slowly towards higher frequency ranges due to the morphological changes. On the other hand, effect of complex morphology of e-waste-based mixtures are also studied. These heterogeneous mixtures are developed using the cutting mill and blending methods that can provide the absorption in higher frequency with very narrow bandwidth. In this manner, effect of morphology on single layer microwave absorption performance of developed heterogenous material is proposed. It is also explored that the developed samples cover a wider bandwidth by utilizing the multilayering technique. A three-layer absorber is designed using genetic algorithm and the results are also validated. The structural and morphological study of the developed heterogeneous materials has been done using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis. Also, rigorous study has been done on magnetic properties and Cole-Cole plots to understand the magnetic and dielectric losses respectively occurring inside the materials. The results showed wide bandwidth absorption of 11.62 GHz (≤−10 dB bandwidth) in the lower frequency region ranges from 0.5 to 12.12 GHz (i.e., L, C, and X-band). The total thickness achieved is 1.85 mm which is very compact (<2 mm). Thus, a thin and wideband microwave absorber at lower frequency range using heterogeneous morphology of developed materials is also presented. The proposed microwave absorbing materials can be potentially utilized for the shielding applications. [Display omitted] • Study explores the impact of morphology on microwave absorption in heterogeneous mixtures. • Milled Carbonyl iron and its mixture exhibit absorption in lower frequency regions. • E-waste-based mixtures with complex morphology exhibit absorption in higher frequency regions. • Multilayering techniques extend bandwidth, with a three-layer absorber designed using genetic algorithms. • Wideband absorption (11.62 GHz) achieved in the lower frequency range (0.5–12.12 GHz) at a compact (<2 mm) thickness. [ABSTRACT FROM AUTHOR]

The object of the study is a compact heptagonal broadband antenna specially designed for use in the 5G millimeter band using Koch fractals to improve performance. As a result of the study, the most important problem of achieving higher gain, improving bandwidth and reducing interference at higher frequencies, which is necessary for the effective functioning of 5G networks, was solved. As a result, the maximum realized gain of 5 dB was obtained at a frequency of 27.58 GHz with an impressive bandwidth in the range from 26.5 to 40 GHz. The use of Koch fractal geometry and defective ground planes significantly improves impedance matching and expands bandwidth, which explains the excellent antenna performance compared to traditional designs. The features and distinguishing features of the results obtained, thanks to which they allowed solving the problem under study, are its compact dimensions (only 9 mm by 9 mm) and the ability to maintain VSWR at a level of less than 2 in the entire frequency spectrum. These features make the antenna particularly suitable for millimeterband integration and flexible applications such as portable devices and wearable home appliances. The field of practical application of the results includes integration into portable and wearable devices, improving the performance and connectivity of Internet of Things applications. The conditions of practical use require compliance with 5G network standards and compatibility with millimeter-wave technologies. This characterizes the antenna as a significant achievement in antenna technology, demonstrating its potential for widespread adoption in next-generation wireless communication systems and paving the way for more reliable and highperformance wireless networks. [ABSTRACT FROM AUTHOR]

We propose a high efficiency wideband three-fold geometric phase metasurface for versatile operation of transmission and reflection. The transmission coefficient as high as 87 % is achieved in the frequency range of f1 (15.4–15.8 GHz), while equal transmission and reflection are achieved in two frequency bands represented by f2 (14.6–15.2 GHz & 16–17 GHz) with maximum coefficient reaches 49 %. With geometric rotation, the phase shifts of the cross-polarized transmission and co-polarized reflection are six times the rotation angle within the frequency range of 14.6–17 GHz. Furthermore, by elaborately breaking the mirror symmetry while preserving rotational symmetry, interesting features of resonance frequency shift and mode splitting are observed, offering a more fruitful approach for versatile operations. To substantiate the proposed design, a metasurface prototype for vortex beam generation is fabricated and verified by microwave measurement.

In this paper first a dual band bandstop filter is proposed using a unique spiral defect at the signal plane for Wi-Fi communication and remote sensing applications. The spiral defects is studied, simulated and measured. Next proposed spiral defect is combined with the hexagonal head defected resonators at ground plane to improve the rejection band. In addition a study is also done to observe the effects of the proposed defects at both signal plane and ground plane. A comparison is done among the response of individual defects filters and combined defect filter. It is observed that later shows improved overall bandwidth with compactness. The proposed combined defect filter with improved stopband displays 92.6% FBW and 112.5 dB/GHz sharpness factor with very compact in size as 0.26 λ0 × 0.25 λ0. All measurement results are in good agreement with the simulated results.

This article presents a newly developed quad port-MIMO antenna, showcasing notable advancements in performance and an extensive impedance bandwidth. The antenna design is founded on a symmetrical configuration, incorporating an X-shaped decoupling structure, alongside employing the multi-slit and multi-slot techniques. These enhancements culminate in a compact, low-profile antenna measuring 40 × 40 × 0.8 mm, while maintaining a remarkable wideband capability. For experimental purposes, the proposed antenna is fabricated using Roger RT/Duroid 5880 with a dielectric constant of 2.2 and a thickness of 0.8 mm. Our investigations reveal that the antenna's impedance bandwidth spans from 22.5 to 29.2 GHz (bandwidth of 6.7 GHz), ensuring isolation levels surpassing −27 dB. The designed MIMO antenna offers an envelope correlation coefficient of 0.004, a diversity gain of 10.0 dB and a peak gain of 4.25 dB. Remarkably, this antenna successfully balances wide bandwidth, compact dimensions, outstanding isolation and superior MIMO diversity metrics. These qualities make it a desirable choice for 5G new radio bands N258 (24.25–27.5 GHz) and N261 (27.5–28.35 GHz) applications. [ABSTRACT FROM AUTHOR]

The primary goal of this study is to design a simple antenna that has a wide bandwidth and low return loss for biomedical applications. The paper shows the recommended antenna's three-stage modeling, with the goal of assessing every important parameter while a Teflon or polytetrafluoroethylene (PTFE) polymer substrate is used. In order to better comprehend, a comparison with prior studies employing teflon and similar substrate materials is conducted for the proposed patch antenna. The analysis includes the phantom model, evaluating performance criteria such as specific absorption rate (SAR), return loss, bandwidth, and gain values relevant to biomedical applications. The antenna works at two different frequencies: 9.73 and 9.39 GHz, one in free space and another in a skin-cotton layer. The bandwidth of the antenna is 4.067 GHz in free space at the resonance frequency of 9.73 GHz, where the return loss is -62.18 dB. The performance of the proposed antenna in the field of biomedical applications, its underlying reasons, and its impacts are discussed in detail in this study. [ABSTRACT FROM AUTHOR]

In this paper, an analysis and testing are carried out on a Ultra wideband (UWB) microstrip patch antenna with low profile, simple structure and low metallization. The antenna geometry consists of a simple semi-circular ring radiator fed by a microstrip line with a defected ground. A semi-circular ring as radiating element, and a ground plane cuts used to achieve ultra-wide impedance bandwidth with low occupation volume and metallization. Low metallization allows for faster manufacturing by increasing prototyping speed. The proposed antenna is fabricated on FR-4 substrate having a dimension of 26×27×1.6 mm3. The SCR antenna resonating at 9.3 GHz with reflection coefficients of -18.07dB, the antenna has a wide band operating rage from (3.25 to 13.8) GHz with a bandwidth of 10.55 GHz and a maximum gain of 2.99dBi. An equivalent circuit is also shown to predict the scattering parameters. Good agreement between the simulated and measured results is observed. [ABSTRACT FROM AUTHOR]

High‐gain directive antennas are used to support point‐to‐point long‐range wireless communication channels. In typical designs, the array factor plays the key role, while individual elements' layout is simplified. Herein, a four‐element phased array is demonstrated, where a volumetric form factor of each element is taken as an advantage to elevate the antenna gain while keeping the device footprint small. The two‐step design process, encompassing a genetic topology optimization and finite tuning with a particle swarm algorithm, is applied and subsequently demonstrated. This shows that exploring the third dimension allows obtaining more than 25 dB isolation between adjacent radiating elements and, at the same time, grants them highly directive radiation patterns. This operation principle is verified by demonstrating a large number of resonating multipoles constructively interfering to create a directional beam. The antenna with a πλ2 aperture demonstrates more than 13 dB gain around 3 GHz frequency range. Antenna elements are 3D printed in resin and then metallize electrochemically. Additive manufacturing of complex volumetric architectures with a small interelement spacing allows implementing new devices, encompassing the advantages of resonant approaches and arrays factors. Miniaturized 3D antenna array devices can be used in wireless communications where controllable beam properties are demanded. [ABSTRACT FROM AUTHOR]

The unit cell structure design and mathematical simulation models of a wideband Metamaterial Light Absorber (MLA) operating in visible range (450 – 750 THz) based on a tungsten metal, based on a Stepped Impedance Resonator (SIR) model is presented. The MLA is being analyzed for electron mobility to achieve significant light photon conversion to use this technology in solar cells for energy harvesting applications. A Metamaterial Light Absorber based on a three-layered metallic semiconductor optical thin film structure is proposed. The top metallic layer is made by Tungsten. Semiconductor layer is developed by silicon and the whole structure is developed over a glass substrate and the same procedure is validated using the Finite Element Method (FEM).The design was subjected to a number of parametric analysis in order to obtain the optimal physical dimension. The various analysis has also much elucidated the process of absorption. Based on the simulation model, the proposed MLA has two peak absorptions of 100 and 99% at 567 THz and 645 THz respectively. The positive light absorption is more than 75% from the frequency range of 545 to 680 THz and produced positive absorption over the whole visible spectrum (450 – 750 THz).The predicted electric field distributions indicate an increased wideband absorption is induced by the stimulation of local and propagating surface electrons and guiding mode resonances. The proposed MLA based on tungsten SIR has the potential to be used in solar cells, solar energy harvesters, solar thermo-PVs, etc. [ABSTRACT FROM AUTHOR]

Unmanned Aerial Vehicle or drone technologies have spread rapidly into areas such as search and rescue, monitoring, surveillance, emergency assistance, delivery of goods, and aerial photography and video. The design of compact, low cost, and multi resonant frequency antenna models has become a critical research study for these applications. Although one of the most popular antenna designs that have such specifications are Microstrip Patch Antennas (MPA), they have the handicap of narrow operation band. Stacking is one of the techniques that not only improve the bandwidth of the antenna but also makes it possible to increase its gain and expand its operation band. Herein, design of a low cost low weight wideband Stacked (MPA) design suitable for WLAN drone communication applications is studied. By using unique features of 3D printing technology the proposed design will be prototyped for satisfying the aimed design goals. For this purpose, the antenna is simulated in CST Microwave Studio by a 3D electromagnetic based model, and maximum gain level that is approaching 9.3 dBi at 5.8 GHz frequency has been achieved. Next, the antenna design is prototyped using 3D printing technology, and a gain level of 7.5, 8.3 dBi are measured at the operating frequencies 5.2 GHz and 5.8 GHz WLAN applications. The results show that the proposed antenna achieves higher performance than its counterparts in literature based on measures such as operation bandwidth, gain, size and manufacturing costs. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact planar coronavirus antenna is proposed for wide band applications. In the design of this antenna, the idea of the radiating part has been taken from the 3-D model of the coronavirus, which is fed by a 50 Ω coplanar waveguide. The patch structure and the feed line of the proposed antenna, which have been made of gold, are located on a polyamide substrate with a thickness and dielectric constant of 45 µm and 3.5, respectively, and the antenna has compact physical dimensions of 300 × 300 µm2. The simulation results of the antenna have been analyzed in terms of S11, VSWR, radiation pattern, gain and surface current distribution. The designed antenna covers the frequency band from 0.3627 to 0.5918 THz for S11 ≤ − 0 dB with a fractional bandwidth of > 47.98% and with a bandwidth ratio of 1.63:1. This extended bandwidth coverage allows the antenna to be suitable for a wide range of applications including wireless communications, internet of things, wearable devices, on-chip antennas and multiple-input multiple-output systems. Also, the results of the far-field show an omnidirectional radiation pattern with an average gain and efficiency of 4 dBi and 93% throughout the frequency band, respectively. [ABSTRACT FROM AUTHOR]

Rectangular Dielectric Resonator Antenna (RDRA) is utilized for the wireless communications system because of its miniaturized size and low profile. This paper presents a design and simulation of slotted RDRA for satellite communication. The major aim of the work is to attain a high gain and radiation efficiency. Hence, the parasitic patch is introduced in this work to achieve this requirement. In this work, the RDRA is designed with a compact size of 10 × 10 × 3 mm, which operates at 17.04 GHz for satellite communication applications. The design is evaluated on the substrate ROGERS RT DUROID 5880, and the antenna comprises Alumina (Al2O3) ceramic material. The slotted design provides better impedance bandwidth and gain. The entire work is simulated in Ansys HFSS software. The performance measures like gain, return loss, radiation pattern, VSWR and directivity are simulated and fabricated. The proposed design provides circularly polarized characteristics at 3 dB and better radiation efficiency of 100%. At last, the fabricated design prototype is analyzed and provides better performance. The simulated and fabricated outcomes proved that the proposed slotted RDRA is efficiently exploited for satellite communication. [ABSTRACT FROM AUTHOR]

In this letter, a wide‐band antenna with dual open rings resonator (DORR) is presented for ambient radio frequency (RF) energy harvesting applications. The proposed antenna is designed to harvest RF energy at DCS1800, UMTS/LTE, and Wi‐Fi bands (1.7–2.65 GHz). The DORR produces a strong coupling effect and leads to more current paths, thus contributing to a wider bandwidth. The measured bandwidth is from 1.68 to 2.80 GHz with 50% fractional bandwidth. The measured gains are 3.5, 5, and 5 dBi at 1.83 GHz (DCS1800), 2 GHz (UMTS/LTE), and 2.45 GHz (Wi‐Fi), respectively. Moreover, over 90% radiation efficiency and larger than 3 dBi gain are achieved for the operating bands. The antenna can be used for RF energy harvesting and various communication applications. [ABSTRACT FROM AUTHOR]

Microstrip‐line fed annular ring circularly polarized antenna is proposed in this work. The antenna is fabricated on a disk‐shaped FR‐4 substrate with annular ring slots etched in the ground. The overall space requirement of the antenna is 25 × 25 × 1.6 mm3. The antenna is modeled for triple notch wide band circular polarization operation in the frequency range from 2–4 GHz. A wide impedance band operation is be obtained by the introduction of slots and stubs. An impedance band‐ width of 1.8 GHz is accomplished with three notches at 2.4, 2.8, and 3.3 GHz. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The three dimensional printing method is currently on stage of rapid development to realize complex nature of structure in simpler and feasible ways. In this paper, we proposed a 3D printed wideband antenna structure with high performance to improve the characteristics properties of feed source by eliminating the use of expensive superstates. A 60 mm $\times60$ mm $\times22.5$ mm wideband structure was first fabricated from VERO CMYK material through Multijet 3D printing method where the bottom layer are copper painted so as to realize the higher permittivity layer. The proposed structure is maintained at 16 mm ( $0.64\lambda $ ) above the ground plate of 60 mm $\times60$ mm $\times $ 1 mm, which is feed by WR-75 waveguide. The proposed antenna is designed to have a wide operating bandwidth from 10 to 15 GHz, which cover Ku-band frequency range. Directivity enhancement is obtained over a large bandwidth by using high permittivity material for Layer 1 and lower permittivity material for Layer 2 and Layer 3. The resulting antenna prototype demonstrates a directivity bandwidth product (DBP) of 3012.79 and DBP per unit area (DBP/A) of 523.06, where directivity and gain are found to be higher than 15 dBi over the entire operating frequency band. The total area of the new antenna prototype is $2.4\lambda \times 2.4\lambda \times 0.9\lambda $ ( $4.16\lambda _{g} \times 4.16\lambda _{g} \times 1.56\lambda _{g}$ ), and overall electrical height is $1.54\lambda $ at the design frequency of 12 GHz. The proposed prototype weight 36 g and overall system have weight of 118 g, which is light in weight. The measured VSWR is less than 2, which signifies wideband characteristics of overall system.

In this paper, we present a novel design approach for a wideband non-uniformly spaced linear array (NUSLA) to suppress the effect of interference signals. Notably, a uniform linear array (ULA), which is easy to handle, is widely utilized to generate nulls over a wide band; however, its beamforming performance is limited owing to the ULA structure. Although a NUSLA with nonlinear spacing addresses nonlinear problems that are difficult to handle mathematically, it can exhibit performance improvements surpassing those of ULA structures. However, an additional constraint is required to generate nulls at a specific position, and this has not yet been studied for null generation using wideband NUSLA. In this paper, we propose a novel cost function for designing a wideband NUSLA, which generates a null at the desired position, and we utilize the modified reinforcement learning algorithm (MORELA), which is a heuristic optimization algorithm based on reinforcement learning (RL), to minimize the proposed cost function and analyze the optimized antenna array and weights. Further, we compare the performance of the proposed MORELA based on RL with that of existing heuristic optimization algorithms via computer simulations. [ABSTRACT FROM AUTHOR]

This brief presents an input buffer based on AC-coupled flipped source follower (SF) for a 12-bit 8-GS/s time-interleaved (TI) ADC. The flipped SF can drive the ADC’s sampling capacitance with high linearity because the input MOS’s drain current is almost independent of the load capacitance. In addition, the inherent feedback reduces the input buffer’s output impedance, which improves the bandwidth when driving the complex wiring network of TI ADCs. The proposed AC-coupling structure enlarges the input signal range of the flipped SF extensively, making it practical to be used for high-speed ADCs. A compensation capacitor is used to compensate for the nonlinear parasitic capacitance of the input MOS to further improve the linearity. An 8-channel 12-bit 8GS/s TI ADC prototype with the proposed input buffer is implemented in a 28-nm mixed-signal CMOS process. Measured results show that the input bandwidth of the input buffer exceeds 6 GHz with 137-mW power supply. The ADC achieves SFDR of 68 dBFS and SNDR of 54.9 dB with 3.9-GHz, −1-dBFS input signal under 8-GS/s sampling rate. The total power consumption of the ADC is 1.05 W. [ABSTRACT FROM AUTHOR]

An aperture coupled miniature dielectric loaded wide band circularly polarized implantable antenna is designed in this article. The antenna is proposed to operate in industrial, scientific, and medical band (2.4–2.48 GHz) for implantable biomedical applications. A square alumina ceramic dielectric material is used for miniaturization which leads to improvement of antenna bandwidth and gain. All the parameters of antenna are evaluated in a homogeneous cubic skin box and measured in saline solutions and minced pork both. The designed antenna has a simulated impedance bandwidth (|S11| < −10 dB) and axial ratio bandwidth <3 dB of 22% (2.21–2.75 GHz) and 7.36% (2.35–2.53 GHz), respectively and maximum −28.96 dBi peak gain observed at resonance frequency of 2.445 GHz. The proposed antenna confirms to the safety guidelines of IEEE standards of specific absorption rate (SAR). The simulated SAR is showing a low value of 11.64 W/kg average over 1 g tissue when input power is set to 1 W. Circular polarization, wide band, and very low SAR are the key features of the designed antenna. To validate the proper communication and data telemetry range with receiver antenna, link budget calculation has been done for designed antenna at 7 and 100 kbps data rates. [ABSTRACT FROM AUTHOR]

A wideband transmissive surface with identical slots on 15 × 15 unit cells proposes in this article. The high gain transmitarray antenna presents using Huygens' principle at 15 GHz. The transmitarray surface consists of trilayer H-shaped slots on the middle of four symmetric slots on the edges of the unit cells. The placed slots induce Huygens' resonances at three frequencies, 13.5 GHz, 15 GHz and 16.7 GHz which is caused by electric and magnetic surface currents on the transmitarray surface. This makes a wide bandwidth for the antenna performance. 360° phase distribution is obtained by increasing the H-shaped slots legs. Since no dielectric substrate used between layers, the transmission coefficient is near 1 (0 dB) through the whole range. For experimental results, the trilayer artificial metallic surfaces with substrateless conductive slotted unit cells is fabricated. The test results presented the transmitarray antenna peak gain is measured 28.6 dB at operating frequency, 15 GHz. Ultra wide band antenna with 3 dB gain bandwidth of 30% and high aperture efficiency of 42.66%. • The main highlights, advantages and novel issues of the presented paper are as follows: • A low profile, wide band and high gain transmitarray antenna for Ku band, consists of tri-layer substrate-less 15 × 15 Huygens' metasurface unit cells. • The equivalent circuit model is examined to attain the optimized values of proposed metasurface unit cell array dimensions. • The transmission phase and magnitude presented transmitarray aperture have been simulated by parametric analysis of proposed unit cell, realized 360° transmission phase scan and nearly full transmission (0 dB). • The Huygens' principle was presented to validate the three resonant frequencies, which is caused by electric and magnetic surface currents on the transmitarray surface. [ABSTRACT FROM AUTHOR]

Development of millimeter-wave wideband receivers is critical for understanding and controlling the nuclear fusion plasma dynamics for renewable energy generation. This article describes the latest progress in the design of a 110–140-GHz wide-intermediate frequency (IF)-bandwidth, 65-nm CMOS chip receiver. This receiver chip includes a radio frequency-low noise amplifier (RF-LNA), actively biased broadband mixer, 2–18-GHz IF-amp, 36–47-GHz tripler, and a 110–140-GHz driver amplifier. The chip size is $1250\times 1150\,\,\mu \mathrm {m}^{2}$ and its total power consumption is 250 mW at 1.8-V bias or 400 mW at 2.5 V. The on-wafer measured conversion gain is 7 dB, noise figure (NF) is 14 dB at 110 GHz, and the RF-IP1dB is −21 dBm. In addition to fusion plasma diagnostics, this 65-nm CMOS receiver is applicable for use in applications such as the high-speed local networking around the 118-GHz oxygen absorption line and millimeter-wave test instruments in the post-5G era. [ABSTRACT FROM AUTHOR]

In this article, an optimized, highly efficient, wideband 1 × 2 Multiple-Input-Multiple-Output (MIMO) fractal antenna is designed for high-speed short-range communication, video rate imaging, medical imaging, and explosive detection in the terahertz frequency band. The suggested fractal THz MIMO antenna configuration is originated from basic rectangular patch antenna through several design iteration steps with partial ground plane structure. A polyimide substrate of thickness 45 µm and dielectric constant of εr = 3.5 is utilized for designing the proposed fractal antenna. The performance of the proposed antenna is enhanced using particle swarm optimization (PSO) technique. The required antenna characteristic parameters like radiation pattern, reflection and transmission coefficient, gain, efficiency, directivity and diversity parameters like channel capacity, envelope correlation coefficient, total active reflection coefficient and mean effective gain are computed using computer simulation software (CST). The effect of chemical potential (μc) of the graphene material is also analyzed and discussed. The designed MIMO antenna covers a wider impedance bandwidth of 400 GHz (0.35–0.75 THz) with coaxial feeding. For the designed MIMO, the patch elements maintain isolation of ≤ − 25 dB throughout the entire operating band. The designed fractal-based MIMO antenna could be a promising choice for the upcoming terahertz applications due to its good impedance, radiation and diversity performance parameters. [ABSTRACT FROM AUTHOR]

An implantable antenna, operating at the dual Industrial, Scientific, and Medical (ISM) bands of 902–928 MHz and 2.4–2.48 GHz, is presented for RF energy harvesting and data transmission. By introducing multiple radiating branches and etching a C-shaped slot, multiple resonant frequencies were generated to produce the wide dual bands. The proposed antenna has compact dimensions of 7.9 × 7.7 × 1.27 mm3. The simulated impedance bandwidths of the antenna are 0.67–1.05 GHz (44.2%) and 2.11–2.96 GHz (33.5%), and the peak gains are −28.9 dBi and −29.5 dBi, respectively. The lower band can be applied in RF energy harvesting, while the upper band is designed for data transmission with external medical equipment. Furthermore, to convert RF power into DC power, in RF energy harvesting, a voltage-doubled rectifier was positioned under the ground plane of the proposed antenna. The rectifier circuit can achieve a maximum conversion efficiency of 52% at an input power of 5 dBm. Furthermore, the integrated scheme of the implantable rectenna was fabricated and the numerical performance of the wireless power transfer was verified with the measurement results. [ABSTRACT FROM AUTHOR]

In this study, a low-frequency multiple-layer metastructure is proposed for broadband vibration control. The effects of the time-delayed vibration absorbers (TDVAs) on the dynamic characteristics of a nonlinear metastructure are explored. First, the effect of using a single TDVA on the metastructure for vibration suppression is studied. The results show that the introduction of time-delayed feedback control is beneficial to improve the vibration suppression of the metastructure in the anti-resonance range. Then, the relationship between the dynamic response of the metastructure and the control parameters of the multiple TDVAs which are evenly distributed is explored. The relationship between the effective vibration suppression frequency band and the control parameters is given. From the results in this study, it is found that the introduction of equivalent damping by time-delayed control can achieve a significant broadening of the effective vibration suppression frequency band. The band gap can be expanded to more than twice its original width. Although the vibration suppression effect in the effective frequency band is slightly deteriorated, the widening of the bandwidth still has important significance. This study gives the method of parameter selection of TDVAs in the multi-degree-of-freedom nonlinear system. [ABSTRACT FROM AUTHOR]

This letter presents a novel unequal bandpass filtering power divider based on hybrid-mode of half mode substrate integrated waveguide (HMSIW) and spoof surface plasmon polaritons (SSPPs). Bandpass response is achieved by combining the transmission properties of HMSIW and SSPPs simultaneously. The operating bandwidth can be designed in a wide range by simply optimizing the dimensions of HMSIW and SSPPs. In addition, defected ground structures (DGSs) are etched on the bottom of the substrate to improve out-of-band suppression. The power division ratio of the proposed unequal power divider is finally optimized to 1:3. The measured results agree with the simulated one. Such design provides a stable power division within wide frequency range from 6.5 to 9.5 GHz.

A quasi‐Yagi antenna with parasitic cells and its array are proposed for 5G mm‐wave bands. For the antenna unit, through introducing the parasitic cells, the gain could be enhanced maximum of 1.3 dB without increasing the antenna length and a wide bandwidth served for the 5G N258 band. Besides, substrate integrated waveguide (SIW) with short‐circuit metal vias is employed as the feed structure and reflector, which can easily tune the impedance matching. For the antenna array, by designing a SIW power divider, the antenna element can be convenient to integrate as a 1 × 4 end‐fire array. The antenna unit and its array have been fabricated and measured. The measured results show that the high peak gain of the element and array is 9.06 and 14.38 dB within the operation bands (24.25–27.5 GHz), respectively. It is suitable for miniaturized end‐fire devices with 5G N258 mm‐wave operation systems. [ABSTRACT FROM AUTHOR]

Tapered slot antennas (TSA) or Vivaldi antennas (VA) arrays studied extensively for many decades have proved to be a potential candidate for wide band (WB) and wide scan (WS) phased array antennas. Earlier analyses have shown that their WB performance suffers from few impedance anomalies due to the coupling associated with surface waves in dielectric substrates and the inter-element gaps in an array. Many researchers have dealt with these problems, proposed metallic TSAs or VAs with elements joined along one of the principal planes (usually E-plane) demonstrating wideband and wide scan capabilities. The author complements the existing research and presents an ultra- WB (UWB), wide beamwidth (HPBW), low cross-polarized (x-pol) and of comparatively smaller size metallic VA (MVA) structure with slotline-to-coax-balun feed. Aluminium metal is used for fabricating monolithic linear arrays positioned together to form a 2D-array. The thickness of MVA reduces the inter-rows gap, thereby removing the impedance anomalies. A Floquet model-based analysis with FEM is used for analysing MVA's performance in an array environment validated with measurements in an 8 × 8 finite array environment. The measurements demonstrate wide beamwidth (>90o;120o), impedance and pattern bandwidth of 127% and 60%, gain >3dBi and x-pol level <−20 dB. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)-based networks combined with Fe 3 O 4 hollow spheres and carbon balls (FCP) for improved electromagnetic wave (EMW) absorption were investigated using an easy-to-industrialize solvothermal and physical method. Hollow structure Fe 3 O 4 spheres with a lower density than that of the common solid sphere were prepared. As a thin and light magnetic material, Fe 3 O 4 hollow spheres generate magnetic loss, carbon balls and PANI networks generate dielectric loss. The magnetic and conductive parts play appropriate roles in achieving complementarity in the EMW absorption. The relatively high specific surface area introduced by PANI networks promotes interfacial polarization and further supports dielectric loss. In conclusion, the above reasons provide multiple attenuation mechanisms. Samples FCP1 (−65.109 dB, at 12.800 GHz, 1.966 mm, from 5.6 to 18.0 GHz) and FCP2 (−61.033 dB, at 8.480 GHz, 3.328 mm, from 4.3 to 18.0 GHz) demonstrated a wide bandwidth, a small thickness, a minimum reflection loss (R L), and a low loading ratio (25%) in paraffin-based composites. Specifically, their loading ration of 25% is much lower than the loading ratio of conventional materials (usually 50% and above). In addition, the bandwidth is excessively wide, above 12 GHz, possessing good absorption performance in continuous intervals with different thicknesses. Such excellent characteristics have rarely been reported in literature. [Display omitted] [ABSTRACT FROM AUTHOR]

An implantable antenna, operating at the dual Industrial, Scientific, and Medical (ISM) bands of 902–928 MHz and 2.4–2.48 GHz, is presented for RF energy harvesting and data transmission. By introducing multiple radiating branches and etching a C-shaped slot, multiple resonant frequencies were generated to produce the wide dual bands. The proposed antenna has compact dimensions of 7.9 × 7.7 × 1.27 mm3. The simulated impedance bandwidths of the antenna are 0.67–1.05 GHz (44.2%) and 2.11–2.96 GHz (33.5%), and the peak gains are −28.9 dBi and −29.5 dBi, respectively. The lower band can be applied in RF energy harvesting, while the upper band is designed for data transmission with external medical equipment. Furthermore, to convert RF power into DC power, in RF energy harvesting, a voltage-doubled rectifier was positioned under the ground plane of the proposed antenna. The rectifier circuit can achieve a maximum conversion efficiency of 52% at an input power of 5 dBm. Furthermore, the integrated scheme of the implantable rectenna was fabricated and the numerical performance of the wireless power transfer was verified with the measurement results.

A circularly polarized implantable antenna integrated with a voltage-doubled rectifier (abbr., rectenna) is investigated for microwave wireless power transfer in the industrial, scientific, and medical (ISM) band of 2.4–2.48 GHz. The proposed antenna is miniaturized with the dimensions of 7.5 mm × 7.5 mm × 1.27 mm by etching four C-shaped open slots on the patch. A rectangular slot truncated diagonally is cut to improve the circular polarization performance of the antenna. The simulated impedance bandwidth in a three-layer phantom is 30.4% (1.9–2.58 GHz) with |S11| below −10 dB, and the 3-dB axial-ratio bandwidth is 16.9% (2.17–2.57 GHz). Furthermore, a voltage-doubled rectifier circuit that converts RF power to DC power is designed on the back of the antenna. The simulated RF-to-DC conversion efficiency can be up to 45% at the input power of 0 dBm. The proposed rectenna was fabricated and measured in fresh pork to verify the simulated results and evaluate the performance of wireless power transfer.

A basic-configured electromagnetic energy harvester is proposed. It operates with varying magnetic induction at the center of a coil. Two magnets are located stable at the center of a coil having a spacer between them. Harvester does not give any elasticity problem with spring-free structure. The importance of coefficient of recovery is explained in theory of harvesters for the first time to our knowledge. The airgap formed by the spacer varies due to the vibration and this generates an electromotive force. It is proven that the proposed harvester generates a voltage amount V rms = 2.41 mV and an electrical power P = 17 μW under the vibration frequency f = 60 Hz with 1 mm displacement. It corresponds to power density of 0.358 μW/cm3. Output voltages show a maxima with V rms = 2.41 mV under R = 0.35 Ohm with a decaying trend with frequency. For R = 0.7 Ohm, higher voltages can be generated till 650 Hz. It is a superiority that this device has a very wide power harvesting regime from 2 Hz to 1.5 KHz. With such a wide characteristics, it can be used for many applications to harvest continuous energy from random vibrating ambient sources with its cheap and basic structure. [Display omitted] • An electromagnetic energy harvester having a basic configuration is designed and implemented. • An analytical expression for the coefficient of recovery of the harvester dynamics is proposed as ξ = 0.856 e − 0.163 v 0 . • Harvester generates 2.41 mV rms voltage and 17 μW power at 60 Hz within 1 mm displacement. • Electromagnetic energy harvester has a wide band operation character between 2 Hz and 1.5 kHz. [ABSTRACT FROM AUTHOR]

In this paper, a wideband high gain Vivaldi antenna based on spoof surface plasmon polaritons metamaterial for radio astronomy application is proposed. The height of the spoof surface plasmon polaritons structures fits the exponential function, thus the structure is named exponential spoof surface plasmon polaritons (ESSPP) metamaterial. With the exponential heights, the ESSPP metamaterial could correct the phase difference in a wide band, the gain is improved in the wide frequency range from 3 GHz to 9 GHz, and the proposed antenna exhibits stable radiation patterns with an average gain of 10.6 dBi. [ABSTRACT FROM AUTHOR]