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Switching-mode power amplifiers have provided unprecedented opportunities for modern wireless communication technology. However, its single-ended structure suffers from significant harmonic interferences on signal transmission; in some cases, higher return loss caused by the impedance mismatch may damage or even destroy the device directly. Here it shows, analytically and experimentally, a broadband push–pull parallel-circuit (PC) Class-E power amplifier (PA) which can present high efficiency and flatness gain over a wide frequency range. Based on the broadband capability of the proposed structure, a highly-efficient push–pull PC Class-E PA combining single reactance compensation technique and Chebyshev low-pass impedance matching network (MN) is designed and fabricated. Experimental results demonstrated that a drain efficiency of 93.71–94.62% operating from 7.0 to 9.4 MHz, as well as output power (Pout) of 42.1–44.57 dBm and power gain of 14.1–16.57 dB are obtained. The measurement results show good agreements with the simulation results, which may be a potential candidate for electronic article surveillance (EAS) applications operating in the high-frequency band. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a broadband high‐efficiency power amplifier (PA) with filtering characteristics is proposed. This PA is designed using a series of inverse continuous modes (SICMs) and adds a novel coupled microstrip line filter structure. The terminal of this structure is composed of microstrip lines cascaded to improve the out‐of‐band suppression effect. This filter can achieve low in‐band insertion loss, high passband selectivity, as well as deep stopband rejection performance simultaneously. A PA was designed and implemented using a 10 W GaN HEMT device, verifying its wideband characteristics. The measurement result shows that the 39.6–41.6 dBm output power (Pout), 61.6%–73.7% drain efficiency (DE), and 8.6–10.8 dB gain are achieved at 2.2–2.9 GHz. [ABSTRACT FROM AUTHOR]

In order to meet the requirements of high efficiency and broadband for the wireless communication system, a high efficiency and broadband gallium nitride power amplifier (PA) is designed and verified. Using the step-matching structure, its bandwidth has been improved. Furthermore, its input matching network is constructed by connecting several microband lines serially to reduce the matching Q value. Meanwhile, the harmonic control network is designed as the output matching network, which is built by a quarter-wave (λ/4) line open circuit and short circuit microwave lines in parallel. Thus, its drain efficiency (DE)can be improved. This design is simulated and tested at 2.2–3 GHz with the gallium nitride (GaN) process. After measuring, it attains an output power (Pout) of 39.5–41.5 dBm, Gain of 10.5–12.5 dB, DE of 65.1%–78.3% with power added efficiency (PAE) of 64.8%–76.2%. [ABSTRACT FROM AUTHOR]

Van der Waals heterostructures (vdWHs) consisting of 2D materials offer a practical and effective approach for engineering multifunctional, high‐performance photodetectors. However, 2D vdWHs photodetectors based on photoconductive effects require an external power input and are often accompanied by a large dark current, which hinders the development of miniaturization and portability of devices and greatly limits the application of devices in complex environments. Herein, a self‐powered photodetector constructed from an InSe/PtS2 vdWH with an extremely low dark current (≈10−14 A) at zero bias and a large rectification ratio of 5.1 × 103 is reported. Leveraging the robust built‐in electric field of the InSe/PtS2 vdWH, the device demonstrates pronounced photovoltaic effects, characterized by an open‐circuit voltage of 0.395 V and a substantial short‐circuit current of 37.1 nA. Remarkably, a high responsivity and detectivity of 211 mA W−1 and 8.58 × 1012 Jones, an excellent light on/off ratio of 0.8 × 107 , and a fast response time of 465/470 µs are achieved, at zero bias. The device showcases a broadband self‐powered photoresponse spanning from 265 to 1064 nm. This study demonstrates the high potential of the InSe/PtS2 vdWH for broadband self‐powered photodetector applications. [ABSTRACT FROM AUTHOR]

Materials possessing broadband antireflective properties benefit applications of military camouflage, photovoltaic devices, and highly transparent windows. In this work, large area, high throughput subdiffraction‐limited motheye‐like metastructures featuring broadband infrared (3–12 µm) antireflectivity are realized through dual‐beam overexposure shrinking strategy and subsequent controllable anisotropic reactive‐ion‐etching process. Both overexposure and overdevelopment processes severely controlled in conventional lithography processes, attribute significantly to improving linewidth resolution to <150 nm when photoresist thickness exceeding 500 nm, even to one micron. For antireflective application, the motheye profiles with customized anisotropic ratio (>3.27) and tunable taper‐angle range (>12.2°) are also realized by regulating the competition of directional ion bombardment and isotropic chemical etching in sulfur hexafluoride (SF6) plasma. The corresponding reflectivity is theoretically well‐simulated and experimentally validated after accounting for the tunable profiles and fractional volume coverage of motheye‐like structures. A low reflectivity <2.0% with the uniformity of ±4.8% and averaged to 1.2% across the overall spectrum of 3–12 µm are achieved. Implementing such efficient shrinking approach can possess huge potential in applications of military camouflage, photovoltaic devices, and highly transparent windows. [ABSTRACT FROM AUTHOR]

A folded transmitarray antenna (FTA) with low profile, high efficiency, and broadband is proposed. The transmission unit‐cell is composed of two metallic layers of bowknot‐shaped patches printed on a single layer of dielectric substrate. By regulating bowknot‐shaped patches' dimension and mirroring elements' top and bottom layers, 360° phase swing and high transmission magnitudes are obtained. With the introduction of a reflectarray integrated with a feed horn in the middle, an FTA is designed based on ray tracing principle, leading to a profile reduced to 1/3 of the focal distance of traditional transmitarrays. According to testing results, 15.5% 1 dB gain bandwidth, 30.9% 3 dB gain bandwidth, and 42.3% peak aperture efficiency are achieved. These outstanding performances demonstrate its good potential for a wide range of high‐gain applications. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are considered as promising next‐generation light sources for optoelectronic and biomedical applications. Nevertheless, NIR phosphors with large bandwidths, long emission peaks, high external quantum efficiencies (EQEs) and valuable thermal stabilities are challenging to develop. Herein, this study reports a novel gallium germanate host, Ga3Al3Ge2O13 (GAGO), with a large bandgap and rigid host lattice for Cr3+ ion doping. The blue LED excitable GAGO:0.012Cr3+ phosphor can produce broadband NIR emission with a maximum intensity at 816 nm and a full‐width at half‐maximum (FWHM) of 187 nm. Notably, the phosphor also exhibits an excellent EQE of 35.8% and perfect thermal stability (I423 K/I298 K = 67.4%). Moreover, an attractive NIR afterglow duration of more than 24 h is achieved in the GAGO:0.004Cr3+ phosphor. The type and origin of the traps are discussed, and a possible long persistent luminescent (LPL) mechanism is proposed. Finally, an NIR pc‐LED based on a GAGO:0.012Cr3+ phosphor is fabricated. The results demonstrate that the obtained phosphors show great potential for use in night vision, nondestructive detection, bioimaging and information encryption. This study provides new insight into the development of broadband NIR luminescent materials with high efficiency, good thermal stability and extraordinary afterglow performance. [ABSTRACT FROM AUTHOR]

For over 35 years of research, the debate about the systematic compositionality of neural networks remains unchanged, arguing that existing artificial neural networks are inadequate cognitive models. Recent advancements in deep learning have significantly shaped the landscape of popular domains, however, the systematic combination of previously trained neural networks remains an open challenge. This study presents how to dynamically synthesize a neural network for the design of broadband electromagnetic metasurfaces. The underlying mechanism relies on an assembly network to adaptively integrate pre‐trained inherited networks in a transparent manner that corresponds to the metasurface assembly in physical space. This framework is poised to curtail data requirements and augment network flexibility, promising heightened practical utility in complex composition‐based tasks. Importantly, the intricate coupling effects between different metasurface segments are accurately captured. The approach for two broadband metasurface inverse design problems is exemplified, reaching accuracies of 96.7% and 95.5%. Along the way, the importance of suitably formatting the spectral data is highlighted to capture sharp spectral features. This study marks a significant leap forward in inheriting pre‐existing knowledge in neural‐network‐based inverse design, improving its adaptability for applications involving dynamically evolving tasks. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a broadband high‐efficiency power amplifier (PA) is designed by using an easily implementable low‐pass filtering network with periodic structure as the output matching circuit to achieve bandwidth expansion of the PA. The proposed periodic structure is based on right‐handed T‐type basic cells, which can achieve wideband filtering responses. In addition, the load design space of the extended continuous Class‐F mode is combined as the target impedance to achieve an efficiency improvement in bandwidth PAs. For verification, a broadband highly efficient PA across 0.6–3.6 GHz with a relative bandwidth of 143% is designed, fabricated, and measured. The test results have shown a drain efficiency of 60.8%–70.4% and gain of 8.5–11.9 dB with a saturation output power under 3‐dB gain compression of 38.5–41.9 dBm. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, the iCGF−1 mode is proposed to compensate the amplitude‐to‐amplitude modulation (AM/AM) distortion of the traditional continuous class F−1 mode while maintaining the high efficiency. The AM/AM profile of the iCGF−1 mode is mathematically expressed simultaneously as a function of the input nonlinearity parameter γ$$ \gamma $$ and conduction angle α$$ \alpha $$, which makes the iCGF−1 mode more flexible in controlling the AM/AM profile. The first inflection point of the AM/AM profile can be moved to a higher output power level through theoretical deduction by adjusting the second harmonic source impedance Z2S$$ {Z}_{2S} $$ and gate bias voltage to increase the values of γ$$ \gamma $$ and α$$ \alpha $$. This flattens the AM/AM profile while the efficiency profile remains almost the same as that of the traditional continuous class F−1 mode. The performance of the iCGF−1 mode is verified through simulation and experimental measurements. The iCGF−1 PA is fabricated with CGH40010F and has a frequency range of 2–2.6 GHz. The drain efficiency is 70.1%–77.9%, and the output power is 41.1–41.7 dBm. The linearity is tested with a 100 MHz 5G NR signal (the peak average power ratio (PAPR) is 8.5 dB) at 2.3 GHz. The worst adjacent channel power ratio (ACPR) is −32.3 dBc without digital predistortion (DPD) and −52.1 dBc with DPD. The results show that the iCGF−1 mode has successfully compensated the AM/AM distortion of the traditional continuous class F−1$$ {}^{-1} $$ mode and maintaining high efficiency. [ABSTRACT FROM AUTHOR]

It is still a challenge to achieve perfect ((near-unity)) absorption across a wide wavelength range with a three-layer structure. This paper presents a metamaterial absorber (MA) based on MXene that can achieve broadband and perfect absorption in the near-infrared and visible regions. The MA with a simple three-layer structure consists of a top Ti3C2Tx layer, an intermediate dielectric layer and a bottom gold layer. It can achieve perfect absorption (the absorptivity over 99%) in the wavelength range of 730–900 nm. The electric field distribution reveals that the localized surface plasmon resonance occurring at the interface of Ti3C2Tx and SiO2 leads to strong absorption over the wide wavelength range. Furthermore, the MA exhibits excellent angular stability. This work provides a method to construct MAs with broadband perfect absorption in the near-infrared and visible band. [ABSTRACT FROM AUTHOR]

In this work, a novel Ba(CoTi)M-spinel magnetic composite with excellent microwave dielectric-magnetic properties has been developed through a hybrid ceramic process. It can be found that the spinel magnetic nanocrystals are uniformly dispersed at the Ba(CoTi)M grain boundary, while the formation of this particular micro-concrete structure has a good effect on ceramic densification and the reduction of magnetic-dielectric loss. The composite exhibits stable electromagnetic parameters in the S and C bands, as evidenced by a permittivity of about 8, a permeability value exceeding 2, and a relatively low magnitude of tanδ ε and tanδ µ on the order of 10−2. A magnetodielectric resonant antenna operating at 6.2 GHz with a −10 dB impedance bandwidth of 27.4%, and a low profile of 0.14λ 0 was designed, fabricated, and measured based on the hybrid ferrite. The hybrid ceramic scheme plays a crucial role in designing low-loss magnetic media, possessing significant application value in high-performance microwave antennas. • Ba(CoTi)M-spinel composite is prepared by a hybrid ceramic processing technique. • The dielectric-magnetic properties are effectively improved in S and C band. • The ferrite enables the miniaturization and wideband capabilities of MDRA. [ABSTRACT FROM AUTHOR]

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have become important as new NIR light sources in NIR spectroscopy and NIR imaging techniques. However, currently developed broadband NIR phosphors commonly suffer from weak emission and poor thermal stability. In this work, a series of Gd 3 Lu 2 Ga 3 O 12 : Cr3+ phosphors were synthesized via high-temperature solid-state reaction. Under 460 nm excitation, the phosphors exhibit an intense emission spanning from 650 to 1150 nm with a full width at half maximum (FWHM) of 122 nm. After introducing Yb3+ as a co-dopant, the emission of the phosphor has been broadened greatly. Interestingly, the studied phosphors demonstrate super high thermal stability in a wide temperature range of 35–560 K, with the integrated emission intensity fluctuating within 10 %. At 435 K, the emission intensity of Gd 3 Lu 2 Ga 3 O 12 : 0.03Cr3+ remains 99.5 % and Gd 3 Lu 2 Ga 3 O 12 : 0.03Cr3+, 0.01 Yb3+ keeps 102.7 % of the initial intensity at room temperature. These NIR phosphors have been encapsulated with a common commercial 460 nm blue LED chip to fabricate a pc-LED device. The NIR output power of the device reaches 23.93 mW@100 mA, with a photoelectric conversion efficiency of 9.81 % at 20 mA current. The applications of the prepared NIR light source in night vision, and bioimaging have been demonstrated. The results show that these Cr3+/Yb3+ doped garnet phosphors can be effectively used in NIR light sources. [ABSTRACT FROM AUTHOR]

Dielectric resonator antennas have been demonstrated to be an efficient radiator, especially with the possibility of fabricating it at low cost based on 3-D printing technologies. However, they have two main limitations which are: their relatively small gain (about 5dBi) and narrow bandwidth. To enhance the gain of DRA, higher-order mode excitation can be utilized; however, typically this has a limit of a few dB increments besides its negative effects on the bandwidth. This study employs a cavity-backed slot to provide an appropriate feeding method for a cylindrical dielectric resonator antenna (CDRA). This design effectively facilitates the excitation of higher-order modes, resulting in a significant gain of up to 15 dBi, which is essential for many wireless systems that are unable to support larger aperture sizes through the standard use of arrays. Additionally, two modes are excited to keep a relatively broadband of about 15 %. The proposed design consists of a cylindrical dielectric placed on top of a cavity-backed slot that is excited by a coaxial probe soldered to the top patch of the cavity. With this feeding, a good matching is achieved for different dielectric resonator heights, hence, the gain can be adjusted easily without the need of reoptimizing the antenna or the feed structures. The design process is explained in addition to performing a sensitivity analysis of fabrication tolerances which confirms that the 3-D printer provides enough accuracy with a negligible effect on the antenna's performance. Then a prototype with a medium length is fabricated and measured to provide high realized gain and impedance bandwidth of 11 dBi and 14.5 %, respectively. The measured data demonstrate the good performance of the antenna with great matching compared to the simulated ones. Furthermore, the antenna presents a good performance in terms of sidelobes and polarization. This proposed design outperforms other DRA designs based on higher-order modes. [ABSTRACT FROM AUTHOR]

This paper presents a three-channel reconfigurable step attenuator based on radio frequency (RF) microelectromechanical system (MEMS) switches, in response to the current issues of high insertion loss and low attenuation accuracy of attenuators. The coplanar waveguide (CPW), cross-shaped power dividers, RF MEMS switches, and π-type attenuation resistor networks are designed as a basic unit of the attenuator. The attenuator implemented attenuation of 0~30 dB at 5 dB intervals in the frequency range of 1~25 GHz through two basic units. The results show that the insertion loss is less than 1.41 dB, the attenuation accuracy is better than 2.48 dB, and the geometric size is 2.4 mm × 4.0 mm × 0.7 mm. The attenuator can be applied to numerous fields such as radar, satellites, aerospace, electronic communication, and so on. [ABSTRACT FROM AUTHOR]

Wireless Power Transfer (WPT) can effectively solve the problem of autonomous power supply for low-power devices. Rectifier is the key component in WPT technology. In this paper, a novel impedance matching network for the broadband rectifier is proposed. This impedance matching network compensates for the diode impedance and reduces its impedance change when the frequency or input power changes. The passive boosting mechanism utilizing coupled transmission lines (CTLs) improves the power conversion efficiency (PCE) of the diode in the low power region. The structure is especially optimized for low-power device applications. For validation, a broadband rectifier operating at 1.9–3 GHz is fabricated and measured. The structure fabricated on the Rogers 4003 substrate with a thickness of 1.508 mm and the diode is HSMS2860. The DC voltage V o u t on the load ( R L = 1300 Ω) was measured. The results show that at 0 dBm, the PCE keeps more than 60% at 1.98–3 GHz. The peak PCE of 79.6% is obtained at 4 dBm. The compact size of the broadband rectifier is 19 mm × 21 mm. This broadband rectifier for low input power ranges can be applied to WPT technology. [ABSTRACT FROM AUTHOR]

The classic vibration energy collector has functional restrictions, and it can only collect vibration energy in one or two dimensions. At the same time, it has issues with low output power in the low-frequency vibration region and a limited reaction frequency range. This research proposes a segmented nonlinear broadband piezoelectric–magnetic coupled energy collector capable of collecting vibration energy in different directions. The collector is equivalent to current state-of-the-art research in that it can collect vibration energy in three dimensions while also having a wide collection frequency and a high power density. The collection consists of a hemispherical support structure and four fundamental piezoelectric beam collision components. The rationality of the collision segmentation nonlinear principle is first clarified through theoretical calculation and analysis, and then the collision design is applied between the ends of different cantilever beams to broaden the captured energy frequency band, while parallel piezoelectric beams use a 45° tilt treatment to fully utilize the geometrical properties of the tilted beams for multidirectional energy collection. In addition, the collector introduces a magnetic coupling effect to create a bistable structure via magnetic contact. Comsol 5.6 software is used to model and simulate the planned 45° tilted beam structure, which clarifies the piezoelectric beam's linear intrinsic frequency characteristics and multi-directional geometric aspects. To further verify the collector's validity, a physical model is built and a vibration experiment apparatus is created. The experimental results demonstrate that the collector's effective bandwidth range is up to 6.3 Hz under 1 g acceleration excitation, representing a 125.0% increase in bandwidth when compared to the cantilever beam with a linear array. At 14 Hz frequency, the collector produces a maximum total output power of 19.52 mW and a power density of up to 3211uW cm−3 when excitation is provided in the Z -direction. [ABSTRACT FROM AUTHOR]

Plasmonic resonant and metamaterial structures allow for manipulating the polarization properties of electromagnetic waves to achieve polarization beam splitting. Broadband polarization‐sensitive metamaterial absorbers based on surface plasmon polaritons have the advantages of high‐energy utilization and excellent stability, which may replace traditional polarizing devices. Here, an absorber based on a ladder network construction is designed theoretically and investigated experimentally. The absorber can possess almost 92% average absorptivity for TM polarization light in 8–12 µm range (experimental result: 83% from 7 to 11 µm). It is especially sensitive to the polarization angle of incident light, and with the increase of polarization angle, the broadband absorption response can present analogously monotonous reduction. The theoretical and experimental results for TE polarization light are 12% and 25%, respectively. The broadband absorption response performs angle insensitive property under oblique incidence. The proposed metamaterial absorber opens a path to realize broadband polarization‐sensitive absorption based on simple nanostructure. It will possess great potential applications in high‐performance polarimetric photodetectors and imaging fields. [ABSTRACT FROM AUTHOR]

Directional control of far‐field thermal emission plays a key role in effective heat and energy transfer. However, conventional photonic strategies are challenging to concurrently control the polar and azimuthal angle of thermal emission over broadband. Here both polar and azimuthal angles of thermal emission are constrained to narrow ranges over broadband by introducing in‐plane anisotropy combined with magneto‐optical materials in the epsilon‐near‐zero (ENZ) wavelength range. The physical mechanism of tunable perfect absorption/emission is explored by investigating the evolution of multiple topological phase singularity pairs (TPSPs). The structure consisting of a magnetized gradient‐ENZ emitter and anisotropic spacer that exhibits high (>0.8) unidirectional emissivity (θ: 55°–79°, φ: 163.5°–196.5°) in the p‐polarization for a broad range of wavelength (22–26 µm) is demonstrated. The unveiled physics synergizing ENZ, anisotropy, and magneto‐optical properties that support broadband unidirectional thermal emission will bring new opportunities in applications such as thermal camouflaging, thermal photovoltaics, and infrared light sources. [ABSTRACT FROM AUTHOR]

Summary: In this research work, a compact‐sized offset‐fed broadband monopole antenna is designed using a frequency selective surface (FSS) reflector to enhance gain, radiation efficiency, and FBR and validated experimentally. The designed antenna consists of a triple v‐slit on a rectangular‐shaped radiating patch, a modified partial ground, and a frequency‐selective surface (FSS). It exhibits a ‐10 dB impedance bandwidth of 9.37 GHz (6.55–15.92 GHz) and a fractional bandwidth of 83.4%, yielding significant portions of the C‐band (4–8 GHz), the X‐band (8 GHz–12 GHz), and covering a considerable part of the Ku‐band (12–18 GHz). The proposed prototype equivalent circuit model has been developed progressively to validate the electromagnetic simulation results. The measured peak gain is 14.25 dBi (6.8 dBi without FSS) at 14.2 GHz with an average radiation efficiency of ≥ 96% for the FSS integrated antenna. Furthermore, the proposed design improves the front‐to‐back ratio (FBR) by 15 dB throughout the broadband frequency range. The proposed antenna peak gain, reflection coefficient (S11), radiation efficiency, and radiation patterns show adequate similarity between the tested and simulated results and have numerous advantages, including very compact size, simple structure, minimum S11 (dB), high gain, and broadband capability. [ABSTRACT FROM AUTHOR]

Metasurface absorbers (MSAs) are of significant importance in a wide range of applications, such as in the field of stealth technology. Nevertheless, conventional designs demonstrate limited flexible characteristics and a lack of transparency, hence constraining their suitability for certain radar stealth applications. This study introduces a novel MSA operating in the broad microwave range, which exhibits both optical transparency and flexibility. The structure consists of a flexible substrate made of polyvinyl chloride (PVC), along with a resistive film composed of indium tin oxide (ITO). The proposed structure exhibits the ability to effectively absorb over 90% of the energy carried by incident electromagnetic (EM) waves across the frequency range of 9.85–41.76 GHz within an angular range of 0° to 60°. In addition, to assess the efficacy of the absorption performance, an examination of the radar cross-section (RCS) characteristics is conducted. The results indicate a reduction of over 10 dB across the aforementioned broad frequency spectrum, regardless of the central angle. [ABSTRACT FROM AUTHOR]

Absorbing near‐infrared (NIR) photons, with longer wavelengths, in atomically thin monolayer MoS2 presents a significant challenge due to its weak optical absorption and narrow absorption bands. Consequently, MoS2‐based photodetector devices often experience low responsivity and a limited detection window. Herein, a novel InAs@ZnSe core@shell/1L‐MoS2 heterostructure, leveraging InAs@ZnSe as the primary infrared‐absorbing material and exploiting the formation of a type‐II heterostructure is showcased. Steady‐state and time‐resolved spectroscopy, along with optoelectronic characterization, are employed to investigate photo‐induced charge transfer dynamics. The results show efficient hole transfer to InAs@ZnSe upon excitation of both materials. Instead, with selective excitation of InAs@ZnSe, electron transfer is observed from InAs@ZnSe to the 1L‐MoS2. The heterostructure demonstrates a broadband photoresponse spanning the wavelength range of 300 to 850 nm, exhibiting a Responsivity of ≈103 A/W and Detectivity of ≈1011 Jones. The signal‐to‐noise ratio substantially increases by 3 to 4 orders of magnitude for 700 and 850 nm excitation compared to pristine 1L‐MoS2. The enhancement in photoresponse and signal‐to‐noise ratio is attributed to increased absorption, which helps eliminate defect and trap states, thereby promoting the photogating effect. [ABSTRACT FROM AUTHOR]

In this paper, a metastructure (MS) based on the metal micro-strip lines (MSL) is proposed to implement the dual-band broadband EIT phenomenon. In this MS, the MSL acts as a bright mode (BM), exhibiting strong resonance with electromagnetic wave (EMW), while the copper backplane with a split-ring hollowed is partially coupled with the MSL structure, which performs as a quasi-dark mode (QDM). Moreover, the structure with ten dielectric cylinders added on top of the MSL structure can be fully coupled with the MSL, thus behaving as a dark mode (DM). In the proposed MS, the EIT effect in two different frequency bands by coupling BM, QDM and DM is achieved. To further study, the structural parameters of the three modes are respectively discussed for the in-depth study of physical mechanisms. Simultaneously, a designed EIT structure is simulated and verified by experiments. The simulation shows that the structure forms two absorption peaks higher than 0.9 at 1.19 GHz and 2.15 GHz, and three transmission dips at 0.8 GHz, 1.56 GHz and 2.91 GHz respectively, that is, the dual-band EIT effect is generated. The experimental results are in good agreement with the simulation results. Generally speaking, the dual-frequency EIT effect of the proposed design is reliable and effective. [ABSTRACT FROM AUTHOR]

In order to improve the vibration isolation performance of current three-parameter damper using bellow and fluid damping, a concept of fluid damper with variable damping and secondary variable stiffness was proposed, a prototype has been designed with several frequency selective valves to adjust the damping characteristics at specific frequency bands, especially that in the low-frequency range. Followed mathematical modelling and simulation of the damper have been carried out, the results show that the designed damper has obtained excellent damping characteristics both in the high- and low-frequency ranges, the micro-vibration isolation efficiency of the damper under realistic excitation of a Control Moment Gyroscope used in a manned spacecraft reaches a significant 71.03 %.The proposed damper concept and designed prototype have laid the foundation for further testing and optimization of high-end isolators for modern spacecrafts. [ABSTRACT FROM AUTHOR]

Identifying sound-scattering organisms is a perennial challenge in fisheries acoustics. Most practitioners classify backscatter based on direct sampling, frequency-difference thresholds, and expert judgement, then echo-integrate at a single frequency. However, this approach struggles with species mixtures, and discards multi-frequency information when integrating. Inversion methods do not have these limitations, but are not widely used because species identifications are often ambiguous and the algorithms are complicated to implement. We address these shortcomings using a probabilistic, Bayesian inversion method. Like other inversion methods, it handles species mixtures, uses all available frequencies, and extends naturally to broadband signals. Unlike previous approaches, it leverages Bayesian priors to rigorously incorporate information from direct sampling and biological knowledge, constraining the inversion and reducing ambiguity in species identification. Because it is probabilistic, a well-specified model should not produce solutions that are both wrong and confident. The model is based on physical scattering processes, so its output is fully interpretable, unlike some machine learning methods. Finally, the approach can be implemented using existing Bayesian libraries and is easily parallelized for large datasets. We present examples using simulations and field data from the Gulf of Alaska, and discuss possible applications and extensions of the method. [ABSTRACT FROM AUTHOR]

In this study, we propose the wide field of view (FoV) radar module for autonomous vehicles. The proposed wide FoV radar (WFR) module was constructed using of an RF module comprising wide beamwidth microstrip patch antennas, an AWR1642 radar sensor chip, and a control module. To achieve a wide FoV of 150° using the fabricated radar module, the 3-dB beamwidth characteristic of the applied microstrip patch antenna had to wider than 150°. The patch antenna was designed using a comb-line structure along 10-by-1 array structure, each radiator characterized by a shorted patch structure, such as a planar inverted-F antenna. The designed antenna was then fabricated on the same board surface as the sensor chip. To identify the characteristics of the implemented radar module, a trihedral corner reflector with a radar-cross-section of 180 m2 was used as the reflector target, and the CA-CFAR (cell averaging constant false alarm rate) target detection algorithm was applied. The measurement results, showed good detection performance of the radar in the view angle of 150°, from -75° to +75°, and a broad bandwidth of 4 GHz in the 77-81 GHz millimeter band. Therefore, the proposed WFR is applicable for used in blind spot detection sensors in autonomous vehicles. [ABSTRACT FROM AUTHOR]

Dielectric resonator antennas have been demonstrated to be an efficient radiator, especially with the possibility of fabricating it at low cost based on 3-D printing technologies. However, they have two main limitations which are: their relatively small gain (about 5dBi) and narrow bandwidth. To enhance the gain of DRA, higher-order mode excitation can be utilized; however, typically this has a limit of a few dB increments besides its negative effects on the bandwidth. This study employs a cavity-backed slot to provide an appropriate feeding method for a cylindrical dielectric resonator antenna (CDRA). This design effectively facilitates the excitation of higher-order modes, resulting in a significant gain of up to 15 dBi, which is essential for many wireless systems that are unable to support larger aperture sizes through the standard use of arrays. Additionally, two modes are excited to keep a relatively broadband of about 15 %. The proposed design consists of a cylindrical dielectric placed on top of a cavity-backed slot that is excited by a coaxial probe soldered to the top patch of the cavity. With this feeding, a good matching is achieved for different dielectric resonator heights, hence, the gain can be adjusted easily without the need of reoptimizing the antenna or the feed structures. The design process is explained in addition to performing a sensitivity analysis of fabrication tolerances which confirms that the 3-D printer provides enough accuracy with a negligible effect on the antenna’s performance. Then a prototype with a medium length is fabricated and measured to provide high realized gain and impedance bandwidth of 11 dBi and 14.5 %, respectively. The measured data demonstrate the good performance of the antenna with great matching compared to the simulated ones. Furthermore, the antenna presents a good performance in terms of sidelobes and polarization. This proposed design outperforms other DRA designs based on higher-order modes.

Reprogrammable metasurfaces, which establish a fascinating bridge between physical and information domains, can dynamically control electromagnetic (EM) waves in real time and thus have attracted great attentions from researchers around the world. To control EM waves with an arbitrary polarization state, it is desirable that a complete set of basis states be controlled independently since incident EM waves with an arbitrary polarization state can be decomposed as a linear sum of these basis states. In this work, we present the concept of complete-basis-reprogrammable coding metasurface (CBR-CM) in reflective manners, which can achieve independently dynamic controls over the reflection phases while maintaining the same amplitude for left-handed circularly polarized (LCP) waves and right-handed circularly polarized (RCP) waves. Since LCP and RCP waves together constitute a complete basis set of planar EM waves, dynamically-controlled holograms can be generated under arbitrarily polarized wave incidence. The dynamically reconfigurable meta-particle is implemented to demonstrate the CBR-CM’s robust capability of controlling the longitudinal and transverse positions of holograms under LCP and RCP waves independently. It’s expected that the proposed CBR-CM opens up ways of realizing more sophisticated and advanced devices with multiple independent information channels, which may provide technical assistance for digital EM environment reproduction.

Abstract A metamaterial-incorporated high-gain and broadband dipole antenna is proposed for 5G mm-wave applications. The designed high refractive index metamaterial (HRIM) properties are presented in detail with supporting results. The proposed dipole antenna achieved broadband features, and the antenna gain increased significantly by incorporating HRIM in the electromagnetic (EM) wave propagation path. Besides, the EM wave aggregation engineering of utilizing the HRIM on the dipole antenna is analyzed using the electric field, magnetic field, and power flow distributions. Both conventional and HRIM-based dipole antenna (HRIMDA) were fabricated on thin (0.254 mm) Rogers RT5880 substrate material with a low dielectric constant of 2.2, where the noticeable gain enhancement by HRIM is observed. The measured results show the operational bandwidth (BW) from 23 to 38 GHz frequency, and the highest gain of 9.5 dBi is accomplished at 35 GHz frequency. Finally, a four-element MIMO configuration is numerically and experimentally analyzed where the isolation of the two conjugated MIMO elements is 9.9 were also achieved. Hence, the proposed HRIM base dipole antenna is a potential candidate for 5G mm-wave applications.

Seeking a more efficient path to improved broadband Internet access.

Abstract Background Although broadband music with inaudible high-frequency components may benefit human well-being, this research area is largely unexplored and lacks sufficient studies on the topic. This study aimed to investigate and compare the effects of broadband and audible band music on relaxation states and cognitive function in young adults. Methods A single-blind randomized controlled trial was conducted in a professional soundproof laboratory from December 22, 2022, to January 18, 2023 with 32 participants randomly assigned to two groups, “Day 1 broadband + Day 2 audible band” (n = 16) and “Day 1 audible band + Day 2 broadband” (n = 16), listening to either broadband or audible band music (the same music piece played on the piano and harp) for two sessions of 15 min each on two consecutive days. Cognitive function was measured using CNS Vital Signs at pre-listening, after the 1st session, and after the 2nd session, while heart rate was monitored throughout the experiment. Visual Analog Scale was also administered for self-reported arousal, stress, thinking ability, and attention following each listening session. Results No significant differences were found in heart rate, cognitive flexibility, and executive function between the broadband listening group and the audible band-listening group (p > 0.05). However, the broadband group exhibited significant differences in mean heart rate at several time points, as well as a significant improvement in VAS stress level during the 2nd listening session compared to the 1st (p

Benefiting from the abrupt phase changes within subwavelength thicknesses, metasurfaces have been widely applied for lightweight and compact optical systems. Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces. However, current metasurface devices mostly adopt discrete micro/nano structures, which rarely realize both merits simultaneously. In this paper, dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation. Via quasi-continuous nanostrips metasurface, a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated. The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000 nm and keep a high power efficiency. The average efficiency of the fabricated metalens reaches 54.24%, showing a significant improvement compared to the previously reported metalenses with the same thickness. The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.

Classification of design codes by the level of complexity of their design was cre-ated for the first time. The obtained results are key to understanding the role of the QR code as a full-fledged work of art in the context of modern design. In the future, this will allow us to single out the most noticeable trends in the development of coded information in the conditions of modern visual culture.

Nowadays, metamaterial absorbers still suffer from limited bandwidth, poor bandwidth scalability, and insufficient modulation depth. In order to solve this series of problems, we propose a metamaterial absorber based on graphene, VO2, gallium silver sulfide, and gold-silver alloy composites with dual-control modulation of temperature and electric field. Then we further investigate the optical switching performance of this absorber in this work. Our proposed metamaterial absorber has the advantages of broad absorption bandwidth, sufficient modulation depth, and good bandwidth scalability all together. Unlike the single inspired layer of previous designs, we innovatively adopted a multi-layer excitation structure, which can realize the purpose of absorption and bandwidth width regulation by a variety of means. Combined with the finite element analysis method, our proposed metamaterial absorber has excellent bandwidth scalability, which can be tuned from 2.7 THz bandwidth to 12.1 THz bandwidth by external electrothermal excitation. Meanwhile, the metamaterial absorber can also dynamically modulate the absorption from 3.8% to 99.8% at a wide incidence angle over the entire range of polarization angles, suggesting important potential applications in the field of optical switching in the terahertz range. [ABSTRACT FROM AUTHOR]

In order to address the 'capacity crisis' caused by the narrow bandwidth of the current C band and the demand for wide-spectrum sensing sources and tunable fiber lasers, a broadband luminescence covering the C + L bands using Er3+/Yb3+ co-doped fluorotellurite glass fiber is investigated in this paper. The optimal doping concentrations in the glass host were determined based on the intensity, lifetime, and full width at half maximum (FWHM) of the fluorescence centered at 1.5 µm, which were found to be 1.5 mol% Er2O3 and 3 mol% Yb2O3. We also systematically investigated this in terms of optical absorption spectra, absorption and emission cross-sections, gain coefficients, Judd–Ofelt parameters, and up-conversion fluorescence. The energy transfer (ET) mechanism between the high concentrations of Er3+ and Yb3+ was summarized. In addition, a step-indexed fiber was prepared based on these fluorotellurite glasses, and a wide bandwidth of ~112.5 nm (covering the C + L bands from 1505.1 to 1617.6 nm) at 3 dB for the amplified spontaneous emission (ASE) spectra has been observed at a fiber length of 0.57 m, which is the widest bandwidth among all the reports based on tellurite glass. Therefore, this kind of Er3+/Yb3+ co-doped fluorotellurite glass fiber has great potential for developing broadband C + L band amplifiers, ultra-wide fiber sources for sensing, and tunable fiber lasers. [ABSTRACT FROM AUTHOR]

In this article, a systematic theory and design approach are presented to achieve bandwidth expansion of the Doherty power amplifier (DPA) by using extended continuous Class‐GF (ECCGF) power amplifiers (PAs) as carrier PAs. The results of the theoretical analysis indicate that compared to conventional DPA, introducing ECCGF PA as carrier PA into the DPA design can establish two larger target impedance spaces with overlapping regions for saturation and output back‐off (OBO) power levels, which can reduce the design complexity of impedance inverter networks (IINs) while achieving DPA bandwidth expansion. Based on this, the proposed design theory is validated in the design and fabrication of a prototype DPA employing the CGH40010F GaN HEMT provided by MACOM. The measured results show that under continuous wave excitation, the designed DPA delivers a saturated output power of 43.1–44.2 dBm in the range of 1.3–2.7 GHz with a relative bandwidth of 70%. The drain efficiencies of 61.2%–73.2% and 42.5%–52.7% are achieved over the entire band at the saturation and 6‐dB OBO power levels, respectively. The measured results also confirmed the theoretical findings. [ABSTRACT FROM AUTHOR]

Nowadays, MIMO technology is one of the hot issues in the development of communication technology. The power dividers have a large role in microwave circuits and it is very important in antenna array systems. This letter presents a broadband eight-way power divider based on the Wilkinson power divider for MIMO communication systems. The power divider is composed of a radial cavity equipped with coaxial probes serving as the power divider circuits, along with microstrip lines loaded with resistors that function as the isolation network. By combining these two parts, the power divider achieves more than 25% operating bandwidth with a theoretical 22.5 dB port isolation. Experimental verification for a C-band (5.8–7.3 GHz) broadband eight-way power divider is presented. Measured results show that the output return loss is better than 18 dB, the isolation is better than 20 dB, and the insertion loss is within 9.03±0.25 dB. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) emitting phosphors draw much attention because they show great applicability and development prospects in many fields. Herein, a series of inverse spinel‐type structured LiGa5O8 phosphors with a high concentration of Cr3+ activators is reported with a dual emission band covering NIR‐I and II regions. Except for strong ionic exchange interactions such as Cr3+−Cr3+ and Cr3+ clusters, an intervalence charge transfer (IVCT) process between aggregated Cr ion pairs is proposed as the mechanism for the ~1210 nm NIR‐II emission. Comprehensive structural and luminescence characterization points to IVCT between two Cr3+ being induced by structural distortion and further enhanced by irradiation. Construction of the configurational energy level diagram enabled elucidation of this transition within the IVCT process. Therefore, this work provides insight into the emission mechanism within the high Cr3+ concentration system, revealing a new design strategy for NIR‐II emitting phosphors to promote its response. [ABSTRACT FROM AUTHOR]

Designing dielectric absorber materials with wideband absorption, wide-angle performance, and lightweight characteristics remains a significant challenge. Inspired by the porous structure of volcanic rock, this study employed a simple one-step hydrothermal method and bubble assistance to synthesize micro/mesoporous Ni2P−Cu3P binary nanophosphides, which were then enhanced with CNTs to create a three-dimensional mesh structure. The porous structure of the Ni2P−Cu3P nanocomposite not only facilitates the formation of rich heterogeneous interfaces on the material surface, inducing lattice defects but also enhances interface polarization due to the uneven surface charge distribution of the pore structure. As a result, at a filling rate of only 10%, Ni2P−Cu3P/CNTs achieved an effective absorption bandwidth of 6.6 GHz with a thickness of 2.4 mm. Furthermore, this nanocomposite exhibited outstanding absorption performance within a wide oblique incidence range of 0−67° for transverse electrical (TE) mode and 0−75° for transverse magnetic (TM) mode. Notably, at reflection loss levels of −5 and −10 dB, the maximum effective oblique incidence angles reached 80° and 67° for TE and TM modes, respectively. These studies underscore the exceptional wide-angle and broadband absorption capabilities of Ni2P−Cu3P/CNTs nanocomposite materials even at extremely low filling rates, making them highly suitable for designing lightweight, broadband, and polarization-insensitive absorbers. [ABSTRACT FROM AUTHOR]

Vertical semiconductor van der Waals heterojunctions are essential for fabricating high-performance photodetectors. However, the range of the spectral response and defect states of semiconductor materials are two critical factors affecting the performance of photodetectors. In this work, the spectral response range of WS2 was changed through WS2 band gap regulation, and a self-powered vertical WS1.08Se0.92/Si heterojunction photodetector with MXene electrode was prepared by synthesizing WS1.08Se0.92 film on Si substrate and vertically stacking Ti3C2T x MXene on the film. Due to the electron collection of MXene and the wonderful junction quality of WS1.08Se0.92/Si, the photodetector can detect near-infrared light in the range of 980–1310 nm, which exceed the detection limit of WS1.08Se0.92. And the device had high sensitivity in the broadband. The responsivity was 4.58 A W−1, the specific detectivity was 4.58 × 1011 Jones, the on/off ratio was 4.95 × 103, and the fast response time was 9.81/9.03 μ s. These properties are superior to previously reported WS2-based photodetectors. Vertical structure, Energy band tuning, and MXene electrode provide a new idea for preparing broadband high-performance and self-powered photodetector. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative design approach for a voltage‐controlled (variable) attenuator that allows continuous control of attenuation through analog voltage. Different from fixed attenuators, this work employs PIN diodes and compensated gold wire inductors to configure the attenuation network. It is based in imperfect matching theory, ensuring to obtain the acceptable S‐parameters over the operating band. Measurement results demonstrate effective performance of the attenuator within the voltage range of 0.7–1.03 V. Return losses of the attenuator are all better than 15 dB in the operating range of 10.5–19 GHz. The insertion losses exhibit continuous variation from 2 to 15 dB, requiring only a single controlled voltage to adjust the attenuation value. [ABSTRACT FROM AUTHOR]

In this paper, a new 180° broadband phase shifter with coupled microstrip line with enhanced coupling by etched slots is proposed, which uses the energy coupling between the parallel‐coupled microstrip lines on the upper layer of the dielectric substrate and the etched rectangular slots (RS) structure on the bottom floor to circumvent the problem for achieving wide operating broadband and low insertion loss with compact size and simple structure. First, the main line and the reference line of the proposed phase shifter are composed of two parallel coupled lines and a uniform transmission line, respectively. Then, its working mechanism is described. Afterward, the phase shifter introduced an RS structure to increase the coupling strength, achieving a broadband of 69.7% and very low insertion loss (0.09 dB) with a phase shift of 180 ± 5°. Finally, a prototype 180° phase shifter with a center frequency of 3.0 GHz was designed, fabricated, and measured, and the measured results are good in agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

Summary: An off‐chip compensation technology for low‐loss and broadband characteristics of radio frequency (RF) switches is proposed based on mathematical analysis of series shunt single pole double throws switches in this letter. This compensation technology can absorb the parasitic parameters of the switch Field Effect Transistor, improving the insertion loss and return loss of the switch as well as supporting higher bandwidth. To verify the design principle, a RF switch, using the SANAN GaAs 0.15 um pseudomorphic High Electron Mobility Transistors (pHEMT) process, and an off‐chip compensation network were designed and implemented. Specifically, after using an off‐chip compensation network, the measured bandwidth of switch has been expanded from 1.1–8.8 to 0.8–11 GHz, while the input and output return loss have also improved significantly. [ABSTRACT FROM AUTHOR]

Through an analysis of the Chinese labor-force dynamics survey (CLDS) data, our study investigates the relationship between broadband infrastructure and happiness among rural households. By leveraging the “Rural BROADBAND” project as an exogenous shock for broadband infrastructure and employing a difference-in-differences (DID) framework, we find that households benefiting from this project experience higher levels of overall happiness after controlling for observables. We put forth two plausible explanations for this noteworthy finding. First, broadband infrastructure facilitates social connections among households by enabling the use of internet-based communication applications. Second, it enhances convenience in daily life by expanding internet accessibility. Furthermore, our research reveals that the positive impact of the broadband construction project on the overall happiness of rural households increases with household income. [ABSTRACT FROM AUTHOR]

Substrate‐borne vibrations are ubiquitous in nature and are used by diverse taxa to communicate and to obtain information about their environments. However, substrate‐borne vibrations remain understudied compared with other sensory and signaling modalities, in part due to human sensory biases. In addition, understanding and quantifying the transmission of vibrations remains a challenging task due to it being dependent on both signal properties and properties of the substrates that the signals transmit through. Here, we provide methods for playing back and measuring the transmission of vibrations throughout a substrate. Using linear resonant actuators, we conducted playbacks of pure tones and frequency sweeps on wooden dowels and on the stems of potted Ptelea trifoliata L. (Rutaceae) plants. We used scanning laser Doppler vibrometry to measure the signals at multiple locations along the length of the dowels and plant stems. We demonstrate that playback of a frequency sweep yields more data in a shorter amount of time than multiple playbacks and measurements of pure tone signals. Our results are also consistent with previous findings showing that signals produce frequency and location specific minima and maxima (nodes and antinodes) throughout the substrates, rather than simply attenuating with distance. This results in filtering of signals, such that their spectra are unique at any given measurement location—illustrating the importance of measuring vibrations at multiple locations. We discuss the implications of such filtering phenomena for vibrationally signaling animals and the biotremologists that study them. [ABSTRACT FROM AUTHOR]

Increasing numbers of students require internet access to pursue their undergraduate degrees, yet broadband access remains inequitable across student populations. Furthermore, surveys that currently show differences in access by student demographics or location typically do so at high levels of aggregation, thereby obscuring important variation between subpopulations within larger groups. Through the dual lenses of quantitative intersectionality and critical race spatial analysis alongside a QuantCrit approach, we use Bayesian multilevel regression and Census microdata to model variation in broadband access among undergraduate populations at deeper interactions of identity. We find substantive heterogeneity in student broadband access by gender, race, and place, including between typically aggregated subpopulations. Our findings speak to inequities in students' geographies of opportunity and suggest a range of policy prescriptions at both the institutional and federal level. [ABSTRACT FROM AUTHOR]

Purpose: To research and evaluate the performance of broadband tailored kT‐point pulses (TP) and universal pulses (UP) for homogeneous excitation of the human heart at 7T. Methods: Relative 3D B1+$$ {\mathrm{B}}_1^{+} $$‐maps of the thorax were acquired from 29 healthy volunteers. TP and UP were designed using the small‐tip‐angle approximation for a different composition of up to seven resonance frequencies. TP were computed for each of the 29 B1+$$ {\mathrm{B}}_1^{+} $$‐maps, and UPs were calculated using 22 B1+$$ {\mathrm{B}}_1^{+} $$‐maps and tested in seven testcases. The performance of the pulses was analyzed using the coefficient of variation (CV) in the 3D heart volumes. The 3D gradient‐echo (GRE) scans were acquired for the seven testcases to qualitatively validate the B1+$$ {\mathrm{B}}_1^{+} $$‐predictions. Results: Single‐ and double‐frequency optimized pulses achieved homogeneity in flip angle (FA) for the frequencies they were optimized for, while the broadband pulses achieved uniformity in FA across a 1300 Hz frequency range. Conclusion: Broadband TP and UP can be used for homogeneous excitation of the heart volume across a 1300 Hz frequency range, including the water and the main six fat peaks, or with longer pulse durations and higher FAs for a smaller transmit bandwidth. Moreover, despite large inter‐volunteer variations, broadband UP can be used for calibration‐free 3D heart FA homogenization in time‐critical situations. [ABSTRACT FROM AUTHOR]

In this study, a wideband circularly polarized (CP) H‐plane horn antenna based on Gap Waveguide (GW) technology in K‐band is presented. The proposed antenna consists of two unconnected metal planes. To produce broadband CP radiation, two main methods are utilized. First, two antipodal tapered plates (ATPs) are added in front of the horn. The ATPs are carefully designed for dissimilar polarization orientations. By this technique, the orthogonal electric fields can be prepared. Then, by embedding three metal square pins near the center of the aperture in both inner plates, the impedance bandwidth (BW) and BW of CP radiation of the proposed horn is entirely improved. Its BW for target |S11| < −10 dB is 18–28 GHz. Also, the peak gain fluctuates between 11.5 and 13 dB. This antenna can provide a 3 dB polarization axial‐ratio BW of about 28.5% (20–26 GHz). Total radiation efficiency is higher than 94%. To verify the design, the proposed structure is manufactured and tested. The proposed horn antenna result has an appropriate agreement between measurement and simulation. Its miniaturized dimensions, easy and cheap fabrication, and broadband CP capability make it a proper volunteer for broadband communication systems. Key Points: We apply Gap Waveguide technology in sectoral horn antenna to reduce the size, bulk, and cost of conventional horn antennasSymmetrical radiation patterns and wideband circular polarization are achieved from two added antipodal tapered plates and three embedded pinsAn antenna is designed for 5G or vehicular satellite communication fields [ABSTRACT FROM AUTHOR]

This paper introduces the design of a circularly polarized metasurface-based antenna array for C-band satellite applications that owns broadband operation and high gain characteristics. The single radiating element comprises a Y-shape patch and an above-placed 2 × 2 unit-cell metasurface. Further improvement in operating bandwidth and broadside gain is achieved by arranging four single elements in a 2 × 2 configuration and a sequential-phase feed network. A prototype has been fabricated and measured to validate the feasibility of the proposed antenna array. The measured operating bandwidth is 20% (4.50–5.50 GHz), which is an overlap between a −10 dB impedance bandwidth of 29.8% (4.50–5.99 GHz) and a 3 dB axial ratio bandwidth of 20% (4.50–5.50 GHz). Across this operating band, the peak broadside gain is 10.5 dBi. Compared with the recently published studies, the proposed array is a prominent design for producing a wide operating bandwidth and relatively high gains while maintaining the overall compact dimensions. [ABSTRACT FROM AUTHOR]