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A broadband high‐efficiency high‐gain empty substrate integrated waveguide cavity‐backed filtenna with dual beams is proposed. The antenna is vertically stacked by three cavities. Two rectangular slots are etched above the uppermost cavity to realize the radiation function. Since the interior of the cavity is covered with metal, the characteristics of the antenna are independent of the used dielectric substrate. The fractional bandwidth of the proposed filtenna is 21.1%, and the efficiency can reach more than 90% in the operational band. The antenna has good frequency selection properties, and the ratio of the −10 dB impedance bandwidth to the −3 dB impedance bandwidth is 0.88. Good gain flatness is obtained, the maximum gain of the filtenna within the operational band is 8 dBi. The proposed dual‐beam filtenna can realize broadband and filtering simultaneously, with low cost and high efficiency. It can be used in wireless communication systems. [ABSTRACT FROM AUTHOR]

This paper introduces a gain‐enhanced, beam‐squint rectified balanced antipodal Vivaldi antenna (BAVA) with symmetrically sliced fins and a novel square‐shaped metallic labyrinth director. The proposed antenna operates from 2 to 18 GHz with S11 less than −10 dB maintaining a fractional bandwidth of 160%, realizes 12.564 dBi as maximum gain at 18 GHz, and achieves greater than 3.415 dBi gain throughout the functioning band of frequency. Improvement of broadside gain by reconfiguration of current loops through symmetric slicing of radiating flares and beam‐squint correction using quarter‐wavelength labyrinth director are addressed by the proposed antenna. The maximum realized size of the antenna is 80 × 40 × 0.508 mm3. Consistent radiation patterns are observed at selected frequencies. Numerical evaluation with a full wave simulation tool and consequent experimental validation with a compact antenna test range is performed. [ABSTRACT FROM AUTHOR]

A K‐band high isolation single‐pole double‐throw (SPDT) switch using a 0.13 µm CMOS process is presented. Two on‐state resistors of shunt Deep‐N‐Well (DNW) transistors are used to improve isolation. The floating‐body technique is utilized to enhance the power‐handling capability. The off‐state capacitors of two DNW transistors are employed to construct an impedance‐matching network. The switch achieves a measured insertion loss of 3.0–3.2 dB and an isolation of better than 35 dB from 17 to 27 GHz. A measured input 1 dB compression power (IP1dB) of 11.8 dBm is obtained at 24 GHz. The chip size of the proposed switch is 0.52 × 0.66 mm2 with a core area of only 0.33 × 0.27 mm2. [ABSTRACT FROM AUTHOR]

Time reversal focusing above an array of resonators creates subwavelength–sized features when compared to wavelengths in free space. Previous work has shown the ability to focus acoustic waves near the resonators with and without time reversal with an array placed coplanar with acoustic sources, principally using direct sound emissions. In this work, a two-dimensional array of resonators is studied with a full three-dimensional aperture of waves in a reverberation chamber and including significant reverberation within the time reversed emissions. The full impulse response is recorded, and the spatial inverse filter is used to produce a focus among the resonators. Additionally, images of complex sources are produced by extending the spatial inverse filter to create focal images, such as dipoles and quadrupoles. Although waves at oblique angles would be expected to degrade the focal quality, it is shown that complex focal images can still be achieved with super resolution fidelity when compared to free space wavelengths. [ABSTRACT FROM AUTHOR]

A 128°YX-LiNbO3-based low-insertion-loss and high-frequency surface acoustic wave (SAW) filter was proposed using COMSOL Multiphysics. The spurious response was suppressed by changing the electrode thickness, reflector period, and reflector structure, after optimization. First, the thickness of the electrode was increased to concentrate the SAW energy on the surface of the piezoelectric material to reduce the propagation loss. Next, an interdigital transducer (IDT) reflector was designed to reduce the insertion loss caused by the spurious response and combined with the optimization of the reflector period. Finally, using this reflector structure when the thickness of the electrode was 0.4 μm, a SAW filter with a center frequency of 2520.5 MHz was designed. The results of the finite element method (FEM) revealed that the insertion loss at the center frequency was –0.1356 dB, the out-band suppression was greater than 30 dB, and the –3 dB bandwidth was greater than 97 MHz. [ABSTRACT FROM AUTHOR]

A novel design for an efficient coupling configuration, which consists of a L-shaped dielectric loaded surface plasmon polaritons (DLSPPs) waveguide and L-shaped nanoantenna, is proposed and investigated numerically in this paper. We carried out the theoretical analysis for the coupling characteristics by utilizing the finite-difference time-domain (FDTD) method. The factors affecting the coupling efficiency of light from free space to the proposed structure were studied in detail, including the structural parameters and incident light source. The simulation results reveal that the coupling performance of proposed structure with optimized geometric parameters is at least three times enhanced compared to that of a single straight DLSPPs waveguide when the incident light is polarized perpendicular to DLSPPs waveguide at a wavelength of λ = 532 nm. The proposed configuration, which is simple and easy to fabricate, can not only achieve the subwavelength mode confinement but also possesses a relatively high coupling efficiency, thus may potentially be used in nano-photonic coupling circuits and nano-optical manipulation. [ABSTRACT FROM AUTHOR]

The effect of doping of Co2+ and Sn4+ in Ba0.5Sr0.5Fe12-2xO19 hexaferrite with different concentrations (x = 0.2, 0.4, 0.6, 0.8, and 1.0) was studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), complex impedance spectroscopy, and analyzed as a dielectric resonating antenna (DRA) at room temperature. The samples were produced and sintered by the solid-state reaction method. Their structure appeared from the M-phase type while their increase in grain size evidenced a dependency on Co-Sn content. The dielectric constant and loss tangent, inferred from impedance spectroscopy, also decreased with the corresponding increase in doping. The real and imaginary impedance decreased with the frequency increment. An electrical equivalent circuit using the Resistance-Constant Phase Element (R-CPE) association was thus proposed, the best-simulated components fitting with the observed structural and microstructure properties. It enabled a better understanding of the microstructure through simulated values of grain/grain boundaries and its effect on tuning the electrical properties in the low-frequency regime. The ferrite characteristics were tested for dielectric resonator antenna applications owing to their good inherent behavior than microstrip patch antenna. Measurement of the radiation efficiency, gain and bandwidth parameters of all the produced ceramics showed that the non-doped one (x = 0.0) exhibits the optimum values: 99.91%, 4.24, and 2.89 GHz, respectively, making the most valuable for antenna applications. [ABSTRACT FROM AUTHOR]

This paper designs a novel E-plane waveguide magic-T in 220 GHz and develops a high-power solid-state power amplifier (SSPA) operating at 210–230 GHz in combination with eight InP high electron mobility transistor terahertz monolithic integrated circuits (TMICs). The 8-way divider-combiner network is composed of low-loss WR-4 novel E-plane waveguide magic-T. The matching load of waveguide magic-T is the air outside the waveguide module, which is connected to the pyramidal horn antenna of WR-4 waveguide to WR-10 waveguide. A monolithically integrated dipole-to-waveguide transition eliminates the need for wirebonding and additional substrates. The low-loss corporate power combining and low-loss dipole-to-waveguide transition achieve high-power combining efficiency of SSPA. The hydroxyl-iron is placed in the upper cavity of TMIC to prevent the cavity from resonance. The SSPA module demonstrated small-signal gain ≥ 10 dB from 210 to 229 GHz. The saturated output power was > 100 mW from 215 to 227 GHz and peak output power of 110 mW with 83% power combining efficiency at 220 GHz. [ABSTRACT FROM AUTHOR]

A Novel Hybrid Choke High Gain Antenna (HCHGA) that operates at 15 GHz is presented in this article, HCHGA is a circularly polarized one that effectively mitigates the multipath effects. The proposed antenna has good impedance matching with S11 of −20.99 dB with a gain of 10.26 dB, and an axial ratio of 1.74 dB. The radiation patterns of the antenna are orthogonal to the antenna surface without any nulls. The proposed antenna is fabricated using RT Duroid 5880 substrate. Simulations are done on a basic patch antenna mounted on different types of ground planes including extended flat ground plane, concentric choke ring, and Hybrid choke ring. The effects of variation in the parameters of grooves thickness, grooves height, and grooves shape on antenna performance parameters are observed. The design of the hybrid chokes facilitated higher values of gain and front-to-back ratio development for mitigating the multipath. From the prototype of the proposed antenna, the measured and simulated results are in good agreement with each other and this proposed antenna is suitable for satellite communication applications. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a multibeam switching antenna based on a low-cost reconfigurable hybrid metasurface applied for beamforming systems. The antenna consists of two parts: a microstrip feed antenna and a transmission hybrid metasurface. The latter is composed of three types of units with different amplitude and phase responses to electromagnetic waves so as to control the beams of the feed antenna. Sixteen PIN diodes are arranged in the metasurface with a simple bias network. When two different direct-current voltages are applied to the PIN diodes, the antenna can dynamically switch between two beams and four beams. For demonstration, the proposed antenna is fabricated, and the measured results show that the antenna operates at 9.07–9.42 GHz (−10 dB bandwidth) with a total size of 1.80λ0 × 1.52λ0 × 0.22λ0 (λ0 corresponds to the wavelength of 9.28 GHz in free space). With the merits of a compact structure, low cost and good radiation performance, the proposed design is suitable for beamforming applications. [ABSTRACT FROM AUTHOR]

A novel compact-slotted four element multiple input multiple output (MIMO) planar monopole antenna is proposed for 5G mmWave N257/N258 and N262 band applications. The antenna, with dimensions of 12 mm × 11.6 mm × 0.508 mm ( 1.036 λ o   × 1.001 λ o × 0.043 λ o where λ o is computed at lowest cutoff frequency), is fabricated on a Rogers RT/duroid 5880 (tm) substrate with a relative permittivity of 2.2 and a dielectric loss tangent of 0.0009. The suggested antenna consists of four U-shaped radiating elements (patches) on top of the dielectric material and a slotted ground on the bottom. The radiating elements are fed by a 50-ohm microstrip line feed. To improve the impedance performance of the MIMO antenna, a rectangular strip of 1.3 mm × 0.2 mm and a couple of rectangular slots are added to each radiating element. The first operating band at 27.1 GHz, ranging from 25.9 GHz to 27.8 GHz, is achieved by using slotted U-shaped radiating elements. The second operating band at 48.7 GHz, ranging from 47.1 GHz to 49.9 GHz, is obtained by etching hexagonal slots on the ground. The antenna design achieves an isolation of >27 dB through the orthogonal positioning of radiating elements and slots on the ground. The designed antenna operates at 27 GHz (N257/N258) and 48.7 GHz (N262) bands, exhibiting stable radiation patterns, a peak gain of >5.95 dBi, radiation efficiency of >90%, an envelope correlation coefficient of <10−6, a total active reflection coefficient of ≤−10 dB, channel capacity losses of <0.03 bits/s/Hz, and a mean effective gain of ≤−3 dB. The simulated and measured results of the antenna show good agreement, making it well-suited for 5G mmWave communication applications. [ABSTRACT FROM AUTHOR]

This paper designs a five-bit microelectromechanical system (MEMS) time delay consisting of a single-pole six-throw (SP6T) RF switch and a coplanar waveguide (CPW) microstrip line. The focus is on the switch upper electrode design, power divider design, transmission line corner compensation structure design, CPW loading U-shaped slit structure design, and system simulation. The switch adopts a triangular upper electrode structure to reduce the cantilever beam equivalent elastic coefficient and the closed contact area to achieve low drive voltage and high isolation. The SP6T RF MEMS switch uses a disc-type power divider to achieve consistent RF performance across the output ports. When designed by loading U-shaped slit on transmission lines and step-compensated tangents at corners, the system loss is reduced, and the delay amount is improved. In addition, the overall size of the device is 2.1 mm × 2.4 mm × 0.5 mm, simulation results show that the device has a delay amount of 0–60 ps in the frequency range of 26.5–40 GHz, the delay accuracy at the center frequency is better than 0.63 ps, the delay error in the whole frequency band is less than 22.2%, the maximum insertion loss is 3.69 dB, and the input–output return rejection is better than 21.54 dB. [ABSTRACT FROM AUTHOR]

In this paper, a wide bandwidth (20 GHz) and small sized (200 × 200 × 50 µm3) terahertz (THz) square graphene ribbon antenna using Photonic Band Gap (PBG) substrate are investigated in the 0.6–0.8 THz band. The proposed antenna consists of graphene as radiating patch mounted on four types of ground plane. The important aim of this work is to eliminate the second resonance frequency by utilize a several types of ground plane and keep a single frequency by improving the performance of the proposed antenna. The effect of change ground plane on the performance of antenna is compared, in terms of reflection coefficient, bandwidth, directivity and radiation pattern. The antenna has achieved good gain (7.62 dB) and good directivity (6.38 dB) in comparison to work reported in the literature. [ABSTRACT FROM AUTHOR]

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This study proposed a simple side-incident TE11 mode microwave probe for the rapid and long-range inspection of cracks in metallic pipes. The probe feeds the microwaves to a metallic pipe, which works as a waveguide; the reflection signal provoked by a defect is measured for detection and localization. The probe enables the detection of both circumferentially and axially oriented cracks, unlike those reported in earlier studies. To achieve better performance, numerical simulations were conducted to evaluate the conversion efficiency and optimize the insertion length of the coaxial cable and the exposed length of the cable core wire. The simulation results suggest that the optimized probe configuration is feasible for pipes with various diameters by proportionally changing the current probe configuration. Although injected microwaves propagated in two directions, the ratio of microwaves to one direction could be controlled by adjusting the inclination angle and the exposed length of the cable core wire. Subsequently, three TE11 probes fabricated according to the simulation results were used to detect circumferential and axial slits in a brass pipe. The results showed that circumferential slits in the vertical positions (parallel to the nontilted coaxial cable) and axial slits in the horizontal positions (perpendicular to the nontilted coaxial cable) caused large reflections, consistent with the electromagnetic field distribution of the TE11 mode microwaves in a circular waveguide. Further experiments verified the feasibility of the designed probe for pipes with different diameters and for directional pipe inspection. [ABSTRACT FROM AUTHOR]

3D holographic azimuthal electromagnetic resistivity logging-while-drilling (LWD) is a convenient and efficient technology to obtain information about formation. It has the advantages of being instant and accurate. It can be applied to fields of engineering such as evaluating anisotropy and detecting nearby geological interfaces. A 3D electromagnetic resistivity azimuthal LWD instrument consists of coaxial, coplanar, tilted and orthogonal antenna systems, being able to solve for all nine components. The explicit generic formulation is derived from presenting the response for a basic unit of one arbitrarily oriented transmitter and one arbitrarily oriented receiver. Combining the responses of basic units with different transmitter-receiver spacing and different components, an 'anisotropy signal' is defined with the phase difference |${M}_{px}$| and amplitude ratio |${M}_{ax}$|⁠. A 'boundary signal' is also defined with the phase difference |${M}_{pz}$| and amplitude ratio |${M}_{az}$|⁠. Forward simulation results show that the 2MHz |${M}_{px}$| can accurately identify geological anisotropy in highly deviated and horizontal wells. The |${M}_{az}$| can detect geological interfaces in highly deviated and horizontal wells. the 100 kHz |${\rm{\ }}{M}_{az}\ $| can detect geological boundaries in the range of 8–9 m. [ABSTRACT FROM AUTHOR]

A 128°YX-LiNbO3-based low-insertion-loss and high-frequency surface acoustic wave (SAW) filter was proposed using COMSOL Multiphysics. The spurious response was suppressed by changing the electrode thickness, reflector period, and reflector structure, after optimization. First, the thickness of the electrode was increased to concentrate the SAW energy on the surface of the piezoelectric material to reduce the propagation loss. Next, an interdigital transducer (IDT) reflector was designed to reduce the insertion loss caused by the spurious response and combined with the optimization of the reflector period. Finally, using this reflector structure when the thickness of the electrode was 0.4 μm, a SAW filter with a center frequency of 2520.5 MHz was designed. The results of the finite element method (FEM) revealed that the insertion loss at the center frequency was –0.1356 dB, the out-band suppression was greater than 30 dB, and the –3 dB bandwidth was greater than 97 MHz. [ABSTRACT FROM AUTHOR]

We report experimental and theoretical results on the extremely large Lamb shift in a multimode circuit quantum electrodynamics (QED) system in the deep-strong coupling (DSC) regime, where the qubit-resonator coupling strength is comparable to or larger than the qubit and resonator frequencies. The system comprises a superconducting flux qubit (FQ) and a quarter-wavelength coplanar waveguide resonator ( λ / 4 CPWR) that are coupled inductively through a shared edge that contains a Josephson junction to achieve the DSC regime. Spectroscopy is performed around the frequency of the fundamental mode of the CPWR, and the spectrum is fitted by the single-mode quantum Rabi Hamiltonian to obtain the system parameters. Since the qubit is also coupled to a large number of higher modes in the resonator, the single-mode fitting does not provide the bare qubit energy but a value that incorporates the renormalization from all the other modes. We derive theoretical formulas for the Lamb shift in the multimode resonator system. As shown in previous studies, there is a cut-off frequency ω cutoff for the coupling between the FQ and the modes in the CPWR, where the coupling grows as ω n for ω n / ω cutoff ≪ 1 and decreases as 1 / ω n for ω n / ω cutoff ≫ 1 . Here ω n is the frequency of the nth mode. The cut-off effect occurs because the qubit acts as an obstacle for the current in the resonator, which suppresses the current of the modes above ω cutoff at the location of the qubit and results in a reduced coupling strength. Using our observed spectrum and theoretical formulas, we estimate that the Lamb shift from the fundamental mode is 82.3% and the total Lamb shift from all the modes is 96.5%. This result illustrates that the coupling to the large number of modes in a CPWR yields an extremely large Lamb shift but does not suppress the qubit energy to zero, which would happen in the absence of a high-frequency cut-off. [ABSTRACT FROM AUTHOR]

We present the use of a set of airbridges to trim the frequency of microwave coplanar-waveguide (CPW) resonators post-fabrication. This method is compatible with the fabrication steps of conventional CPW airbridges and crossovers and increases device yield by allowing compensation of design and fabrication uncertainty with 100 MHz range and 10 MHz resolution. We showcase two applications in circuit QED. The first is the elimination of frequency collisions between resonators intended to readout different transmons by frequency-division multiplexing. The second is frequency matching of readout and Purcell-filter resonator pairs. Combining this matching with transmon frequency trimming by laser annealing reliably achieves fast and high-fidelity readout across 17-transmon quantum processors. [ABSTRACT FROM AUTHOR]

This paper reports the prototype fabrication and characterization of microstrip patch antenna using the sol-gel derived composite nanoparticles of vanadium pentoxide oxide (V2O5) and zinc aluminate (ZnAl2O4). The prepared composite nanoparticles were characterized using X-ray diffraction (XRD), which exhibited the dominant peaks of ZnAl2O4 and V2O5. The crystallite size of the nanoparticles was estimated to be 16 nm. The sample was also studied using the Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS) to examine the functional groups morphology and elemental composition present in the composite nanoparticles. Further, these nanoparticles were employed in fabricating the prototype microstrip patch antenna to evaluate its characteristics. The fabricated antenna showed its return loss of -17.13 dB at a resonant frequency of 4.64 GHz. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method to generate Vector Vortex Modes (VVM) inside a metallic cylindrical waveguide at microwave frequencies and demonstrate the experimental validation of the concept. Vector vortex modes of EM waves can carry both spin and orbital angular momentum as they propagate within a tubular medium. The existence of such waves in tubular media can be beneficial to wireless communication in such structures. These waves can carry different orbital angular momentum and spin angular momentum, and therefore, they feature the ability to carry multiple orthogonal modes at the same frequency due to spatial structure of the phase and polarization. In essence, high data rate channels can be developed using such waves. In free space, Orbital Angular Momentum carrying vortex waves have beam divergence issues and a central field-minima, which makes these waves unfavorable for free space communication. But vector vortex mode waves in guided structures do not suffer from these drawbacks. This prospect of enhancement of communication spectrum in waveguides provides the background for the study of vortex wave in circular waveguides. In this work, new feed structures and a radial array of monopoles are designed to generate the VVM carrying waves inside the waveguide. The experimental findings on the distribution of the amplitude and phase of the electromagnetic fields inside the waveguide are presented and the relationship between the waveguide fundamental modes and VVMs are discussed for the first time. The paper also presents methods for varying the cutoff frequency of the VVMs by introducing dielectric materials in the waveguide. [ABSTRACT FROM AUTHOR]

Quantum hardware based on circuit quantum electrodynamics makes extensive use of airbridges to suppress unwanted modes of wave propagation in coplanar-waveguide transmission lines. Airbridges also provide an interconnect enabling transmission lines to cross. Traditional airbridge fabrication produces a curved profile by reflowing resist at elevated temperature prior to metallization. The elevated temperature can affect the coupling energy and even yield of pre-fabricated Josephson elements of superconducting qubits, tunable couplers, and resonators. We employ grayscale lithography to enable reflow and thereby reduce the peak temperature of our airbridge fabrication process from 200 to 150 °C and link this change to a substantial increase in the physical yield of transmon qubits with Josephson elements realized using Al-contacted InAs nanowires. [ABSTRACT FROM AUTHOR]

Nonreciprocal magnon propagation has recently become a highly potential approach of developing chip-embedded microwave isolators for advanced information processing. However, it is challenging to achieve large nonreciprocity in miniaturized magnetic thin-film devices because of the difficulty of distinguishing propagating surface spin waves along the opposite directions when the film thickness is small. In this work, we experimentally realize unidirectional microwave transduction with sub-micrometer-wavelength propagating magnons in a yttrium iron garnet (YIG) thin-film delay line. We achieve a non-decaying isolation of 30 dB with a broad field-tunable bandpass frequency range up to 14 GHz. The large isolation is due to the selection of chiral magnetostatic surface spin waves with the Oersted field generated from the coplanar waveguide antenna. Increasing the geometry ratio between the antenna width and YIG thickness drastically reduces the nonreciprocity and introduces additional magnon transmission bands. Our results pave the way for on-chip microwave isolation and tunable delay line with short-wavelength magnonic excitations. [ABSTRACT FROM AUTHOR]

In this paper, a capacitively-fed, ultra-wideband (UWB), and low-profile monocone antenna is proposed for vehicle-to-everything (V2X) applications. The proposed antenna consists of a monocone design with an inner set of vias. Additionally, an outer ring is added with a small gap from the monocone and shorted with six folded wires of different lengths to extend the operating band. The proposed antenna covers the frequency range from 0.75 GHz to 7.6 GHz and has a 164% fractional bandwidth, with a gain value varying between 2 and 10 dBi. The dimensions of the antenna are 0.37 λ L   × 0.37 λ L   × 0.067 λ L . The antenna was fabricated using a 3D printer with low-cost polylactic acid plastic (PLA) material and then sprayed with aerosol copper nanoparticles. The efficiency was approximately 90% throughout the frequency bands of interest. Finally, the proposed antenna was installed on a vehicle and tested with an OBU (onboard unit) and a RSU (roadside unit) in the field. The results show a longer wireless communication range for V2X applications. [ABSTRACT FROM AUTHOR]

Herein, a novel and simple design of all‐metal 3D anisotropic metamaterial (3DAMM) is proposed and investigated numerically, which can achieve a high‐efficient and wide‐angle ultrabroadband reflective linear–linear and dual‐band linear–circular polarization conversion in the terahertz (THz) region. The 3DAMM is composed of a periodic array of copper stand‐up split ring resonator (SRR) adhered on a copper film ground plane. Incident ultrabroadband linear polarization waves can be converted to its orthogonal counterpart after reflection due to the three neighboring plasmon resonances of the 3DAMM structure. The proposed design demonstrates a high conversion efficiency of over 90% within a relative bandwidth of 88.7% in the range of 0.62–1.61 THz, and its efficiency is validated for both transverse electric and transverse magnetic modes and a wide range of incident angles (0°–50°). This ultrabroadband and high‐efficient linear polarization conversion of the 3DAMM is attributed to multiple plasmon resonances within the operating frequency range. The surface current distributions on the unit cell show that the ultra‐broadband conversion behaviors result from the decomposed electric field components coupling with different resonance modes. Further simulation results suggest that the polarization conversion properties of the 3DAMM can be adjusted by changing the geometric parameters of the unit cell. The proposed 3DAMM‐based reflective linear polarization convertor can find potential applications in remote sensors, imaging systems, and reflector antennas at THz frequencies. [ABSTRACT FROM AUTHOR]

Due to the growing scarcity of spectrum resources in the low-frequency band, the requirement of beam-reconfigurable antennas in the millimeter wave band is urgent. In this paper, a W-band graphene-based metasurface working in a broad bandwidth is proposed with reflective amplitude coding. Here, graphene sheets play a dual role in radiating and regulating electromagnetic waves. By adjusting the Fermi levels of graphene, the reflective amplitude and phase of the metasurface can be modulated simultaneously, enabling multi-beam switching and beam deflection in far-field. The proposed metasurface achieves amplitude-phase modulation within a significantly wide bandwidth which covers 75–91.5 GHz and 99.3–115 GHz. By optimizing the coding patterns, the proposed graphene-based metasurfaces are able to not only realize 2-D beam steering, but also achieve beam switching from single beam to four beams at 87 GHz. The proposed design provides a novel solution for the flexible manipulation of millimeter waves, which can be applied to various fields such as vehicle radar, satellite communication, 6G wireless communication, and beyond. [ABSTRACT FROM AUTHOR]

A novel transition between rectangular waveguide (RWG) and balanced transmission line with magnetic closed loops has been developed. A conventional RWG directly mounts on a printed circuit board that actualizes energy transition. Using a pair of centrosymmetric magnetic closed loop, the TE10 mode converts to TEM mode, and balanced ports are obtained. Based on the structural characteristics investigation, the transition is fabricated and measured. The center frequency of the operation is 32.5 GHz, and the bandwidth is wider than 27% for insertion loss no more than 0.6 dB and return loss more than 15 dB. Between the two balanced ports, the magnitude imbalance is less than 0.4 dB, and the phase difference is less than 3°. Integration within the balanced ports makes the transition a promising candidate for miniaturized system in antenna. [ABSTRACT FROM AUTHOR]

A miniaturized ultra‐wideband (UWB) bandpass filter (BPF) based on broadside coupled technology with multiple passband notches is reported. The basic geometry of BPF has microstrip lines on the top plane coupled to the modified short‐circuited coplanar waveguide in the bottom plane. This broadside alignment leads to the development of a UWB response with good frequency characteristics due to the presence of two transmission zeros at lower/upper passband edges. Later, multiple circular resonators and one complimentary folded split ring resonator are embedded into the basic architecture to develop triple passband notches at our frequencies of interest. Eventually, a prototype is fabricated and tested to validate the simulated data. The proposed BPF occupies a minimal physical area of 14 × 11.4 mm2. [ABSTRACT FROM AUTHOR]

A wideband patch array operating at D‐band for antenna‐in‐package applications is presented in this paper. The array consists of two symmetrically positioned subarray elements and a grounded coplane waveguide feed line. Four E‐shaped patches are loaded in the array to enhance bandwidth. All geometry of the array is manufactured on a single‐layer quartz substrate without via hole, so that the difficulty and cost of fabrication are relieved greatly. Good agreements of reflection coefficient, pattern, and gain between measured and simulated results are achieved. Measurement shows that the array exhibits a −10 dB bandwidth of 19 GHz from 138 to 157 GHz and a 3‐dB gain bandwidth covering 140–159 GHz with a peak gain of 11.8 dBi at 147 GHz. Properties of wideband, moderate gain, low cost, and easy manufacture are achieved in this array. [ABSTRACT FROM AUTHOR]

In our previous work, we proposed an algorithm to transform the metric of an isolated matter source in the multipolar post-Minkowskian approximation in harmonic (de Donder) gauge to the Newman-Unti gauge. We then applied this algorithm at linear order and for specific quadratic interactions known as quadratic tail terms. In the present work, we extend this analysis to quadratic interactions associated with the coupling of two mass quadrupole moments, including both instantaneous and hereditary terms. Our main result is the derivation of the metric in Newman-Unti and Bondi gauges with complete quadrupole-quadrupole interactions. We rederive the displacement memory effect and provide expressions for all Bondi aspects and dressed Bondi aspects relevant to the study of leading and subleading memory effects. Then we obtain the Newman-Penrose charges, the BMS charges as well as the second and third order celestial charges defined from the known second order and novel third order dressed Bondi aspects for mass monopole-quadrupole and quadrupole-quadrupole interactions. [ABSTRACT FROM AUTHOR]

A CMOS transimpedance amplifier (TIA) with broad band and high gain based on negative Miller capacitance and capacitive degeneration has been proposed and designed. The theoretical analysis shows that by introducing negative Miller capacitance into the feedforward common gate (FCG) amplifier circuit, the bandwidth limitation caused by the internal parasitic capacitance can be reduced, and by cascading the capacitive degeneration-based common source (CS) amplifier as the gain stage, the amplifier gain can be improved simultaneously. The proposed TIA is designed and simulated in TSMC 65 nm CMOS process, The simulation results show that the −3 dB bandwidth of the amplifier circuit is 23.7 GHz, the transimpedance gain is 60.1 dBΩ, the average equivalent input noise current spectral density is less than 40.7 pA/√Hz, the power consumption is 4.8 mW, and the circuit layout area is 0.0027 mm2. In Comparison to the published TIA circuits, the bandwidth of the designed CMOS TIA is increased by 12.7 GHz, the gain is increased by 18.1 dBΩ and the circuit layout area becomes smaller. All the results demonstrate that the designed TIA can be used in the photoelectric detection circuit with broader bandwidth and higher gain. • A CMOS transimpedance amplifier (TIA) with broadband and high gain is presented. • Based on FCG-TIA, negative Miller capacitance and capacitive degeneration are combined to improve the performances. • The bandwidth and transresistance gain of the proposed TIA are 23.7 GHz and 60.1 dBΩ, respectively. • The layout area is small because of the inductorless structure of the proposed TIA. [ABSTRACT FROM AUTHOR]

In this paper, a simple coplanar waveguide fed compact electrically small antenna for dual-band operations without the use of via is presented. The resonances of the structure are obtained by spiraling one of the ground planes of an open-ended CPW transmission line with a short length center feed. The proposed antenna has a geometrical dimension of 0.079λ01× 0.079λ01 mm2 (λ01 is the free space wavelength of first resonant frequency) with a small electrical size (ka) of 0.35. The experimental studies on the fabricated prototype of the proposed antenna show a 2:1 VSWR bandwidth up to 2.53% and 4.12% for 2.3 and 5.3 GHz, respectively. The simulated antenna reflection and radiation characteristics are demonstrated with physical measurements. [ABSTRACT FROM AUTHOR]

This article investigates the possibilities of frequency tuning of a Self-diplexing antenna (SDA) using different liquid dielectrics. Tuning analysis is carried out using the fluidic pockets introduced into the substrate by drilling blind vias starting at the bottom layer. To examine the frequency tuning, the pockets can be filled with either air, olive oil, transformer oil, acetone, or distilled water and sealed with copper tape. The experimental results demonstrate that the proposed antenna can be configured to operate in the 3.25 to 3.52 GHz and 4.5 to 5.04 GHz bands. The proposed SDA is designed and fabricated on a substrate of 1.575 mm thick Rogers 5880 ( ϵ r = 2.2 and tan δ = 0.0009). It is observed that frequency shift is more when using higher permittivity fluids. The proposed antenna model has competitive features such as simple design, compact size ( 0.34 λ g 2 ), better isolation (>30 dB), and fine-tuning, which makes it suitable for modern multiband and multifunctional gadgets. The simulated and measured circuit responses are in good agreement. [ABSTRACT FROM AUTHOR]

As a proof of principle, operation of traveling-wave resonant-tunneling-diodes (RTDs) oscillators has been demonstrated experimentally in the frequency range 100-400 GHz. A theoretical model describing a realistic coupled system, consisting of a traveling-wave RTD and a patch antenna, has been developed. The model describes the eigen resonances and the eigen modes, which have a mixed character of both subsystems. The model and the experimental results are in agreement with each other. We also demonstrate that some oscillators were switching between different resonant modes of the system with the change of bias. The phenomenon could be used for an extended frequency control of the RTD oscillators. [ABSTRACT FROM AUTHOR]

An ultra-wideband and high-gain Vivaldi antenna with artificial electromagnetic material, suitable for ground-penetrating radar (GPR) systems, is proposed. Directors loaded inside the antenna gradient slot direct electromagnetic waves by inducing current to improve gain. The artificial electromagnetic material, also called metamaterial, is composed of multiple "H"-shaped units arranged in a certain regular pattern, loaded at the antenna aperture. The artificial electromagnetic units affect the antenna radiation waves by changing the refractive index to improve radiation directivity. The four Vivaldi units are arranged into a horn-shaped array, and each two units are orthogonally fed to realize dual polarization. Experimental results demonstrate that the antenna has good impedance matching of S 11 ≤ − 10 dB in 0.9–4 GHz, and the maximum realized gain can reach 15.2 dBi. [ABSTRACT FROM AUTHOR]

In this paper, a planar 0‐dB crossover using printed ridge gap waveguide (PRGW) technology is proposed and designed for millimeter‐wave applications. PRGW as a quasi‐TE mode is considered as the modern guiding technology at high frequencies and for the 5G and other upcoming communications. A prototype of the proposed PRGW crossover working around 30 GHz is fabricated and measured to validate the simulated results. Comparing simulated with measured results, a good agreement is observed. The measured results demonstrate that the designed crossover offers an insertion loss of better than 0.5 dB over the whole operating frequency bandwidth from 29 to 31 GHz where the return loss level is better than 15 dB and the isolation level is less than −13 dB. Compared with the other reported crossover structures, the designed PRGW crossover features a wider bandwidth with a smaller and planar configuration. Key Points: A design of planar printed ridge gap waveguide 0‐dB crossover at 30 GHz [ABSTRACT FROM AUTHOR]

This article presents a historical overview of research focused on dielectric resonator antennas (DRAs) over the past few decades. The dielectric resonators (DR) provide the most attractive features as antenna elements, including high radiation efficiency, large bandwidth, small size, most accessible coupling schemes, etc. The essential characteristics of DRAs are described in detail by reviewing the most potent methods for antenna feeding and size reduction. Moreover, recent design solutions for improving the realized gain of particular DRAs are analyzed. Numerous application-oriented DRAs are discussed in this article which helps to make the survey more effective. The DR antenna was utilized in various applications because of the low cost, enlarged design flexibility, and reduced loss. The requirement of 5G communication is fulfilled by using the appropriate antenna with enhanced bandwidth. For 5G communications, a microstrip patch antenna (MSA) is considered a better choice. Also, a low profile wide band hybrid stacked DRA can be utilized for Ku and K band applications. In millimetre wave application, the reduction of ohmic losses is considered the primary goal. Thus, the millimetre wave applications select the DRAs with minimum ohmic losses. Also, the gain enhancement of DRA through different shapes, feed coupling schemes, and various modes are discussed. Finally, the simulation results of several existing approaches are analyzed in terms of gain, radiation pattern, reflection coefficient, radiation efficiency, and return loss. [ABSTRACT FROM AUTHOR]

In this work, a dual-polarized broadband metasurface antenna is proposed. The antenna consists of a new Metasurface patch which is formed from different cross shapes to achieve wide bandwidth and expedite dual polarization features. The radiating metasurface patch is fed by a novel coplanar waveguide fed structure to facilitate achieving dual polarization. The proposed antenna has a wide bandwidth of 2.82 GHz over an operating frequency range between 3.36–6.2 GHz with 10 dBi maximum realized gain. The proposed antenna has been fabricated and the simulated results have been validated experimentally. It is believed that the proposed antenna is a good candidate for sub 6 GHz of 5G application. [ABSTRACT FROM AUTHOR]

Most applications which measure physical quantities, especially in harsh environments, rely on surface acoustic wave resonators (SAWRs). Measuring the variation of the resonance frequency is a fundamental step in such cases. This article presents a comparison between three techniques for best determining the resonance frequency in one shot from the point of accuracy and uncertainty: fast Fourier transform (FFT), discrete wavelet transform (DWT) and empirical mode decomposition (EMD). After proposing a model for the generation of synthetic SAW signals, the question of wavelet choice is answered. The three techniques are applied to synthetic signals with different central frequencies and signal-to-noise ratios (SNRs). They are also tested on experimental signals with different sampling rates, number of samples and SNRs. Results are discussed in terms of the accuracy of the estimated frequency and measurement uncertainty. This study is successfully extended to SAWR temperature sensors. [ABSTRACT FROM AUTHOR]

Electrical and calorimetrical measurements were performed to obtain insight into the energy transformation from input power to the power available for the plasma treatment of substrates in a diffuse coplanar surface barrier discharge used as plasma source and operated in air, N 2 , O 2 , and CO 2 at input power of up to 380 W. Overall input power and applied electrical power were measured, and a conversion of 90% was determined with a constant loss of 30 W for the operation of the control unit. Measurements of the temperature gradient were performed for the electrode oil cooling to identify the power loss due to cooling. With roughly 50% of the applied electrical power, it turned out to be the largest loss term. A ceramic passive thermal probe was used to determine the energy flux from the plasma to a substrate. Highest energy flux values were found to be about 500 mW / cm 2 using air as working gas. Conversion efficiencies from the available electrical power via discharge to the power used for substrate treatment of 50%–35% depending on the working gas (highest for air, lowest for CO 2) were determined. Investigation on the spatial expansion of the surface discharge showed a dependence of the energy flux from the distance above the electrode. The energy flux maximum shifts to larger distances if no oxygen is present in the working gas. [ABSTRACT FROM AUTHOR]

The cyclo[18]carbon was synthesized experimentally for the first time in August 2019 [K. Kaiser et al., Science 365, 1299 (2019)]. The semiconductor property of the cyclo[18]carbon makes it possible to become an essential element of molecular electronic devices. In our work, the electron transport properties of zigzag graphene nanoribbon cyclo[18]carbon-zigzag graphene nanoribbon junction [(8-ZGNR)-C 18 -(8-ZGNR)] were studied, using the non-equilibrium Green's function approach based on the density functional theory. The coplanar and perpendicular configuration constitutes the current ON and OFF state, respectively, with the high ON/OFF ratio approaching to 10 4. A significant negative differential conductance (NDC) with a peak-to-valley ratio of 1.5 in the bias range of 0.3 V–0.4 V was found. The NDC arises due to the resonance of the edge state of ZGNRs and the frontier orbitals of C 18 within the bias window. Moreover, the high current ON/OFF ratio and NDC are robust against variations in the lead's width, length of short-carbon chain, and the bridging way of C 18 on leads. Specifically, the Ipeak/Ivalley of the coplanar configuration with the C 5 spacer can increase to 5.7 in the bias range of 0.4 V–0.5 V. Our computational studies may guide design of multi-functional molecular devices based on C 18. [ABSTRACT FROM AUTHOR]

To realize the multi-functional manipulation of the acoustic field with a simple artificial structure, a waveguide array based on resonant units was proposed in this work. Based on the transmission spectrum and zero-like refractive index of the waveguide unit, the amplitude of the transmitted wave can be manipulated. By changing the size of the waveguide unit flexibly, the phase of the transmitted wave can be manipulated. In addition, by extending the waveguide array to the sub-wavelength scale, an acoustic metasurface with both amplitude and phase modulation functions can be implemented, which provides new ways for the design of lightweight artificial periodic structures. [ABSTRACT FROM AUTHOR]

Combined microwave-optical pump-probe methods are emerging to study thequantum state of spin qubit centers and the charge dynamics in semiconductors.A major hindrance is the limited bandwidth of microwave irradiation/detectioncircuitry which could be overcome with the use of broadband coplanar waveguides(CPW). We present the development and performance characterization of twospectrometers: an optically detected magnetic resonance spectrometer (ODMR) anda microwave detected photoconductivity measurement. In the first method lightserves as detection and microwaves excite the investigated medium, while in thesecond the roles are interchanged. The performance is demonstrated by measuringODMR maps on the nitrogen-vacancy center in diamond and time resolvedphotoconductivity in p-doped silicon. The results demonstrate both an efficientcoupling of the microwave irradiation to the samples as well as an excellentsensitivity for minute changes in sample conductivity.

Titanium nitride (TiN) is a known superconducting material that is attractive for use as passive components in superconducting circuits for both conventional and quantum information devices. In contrast to conventional synthesis techniques, here, plasma-assisted molecular beam epitaxy is reported to produce high-quality TiN on bare silicon wafers. Using a rf-plasma source to crack the nitrogen molecules and a conventional high-temperature effusion cell for titanium, TiN growth is completed under nitrogen-rich conditions. The growth and nucleation is monitored in situ, while the structure and composition are characterized using x-ray diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and scanning transmission electron microscopy. The stoichiometric TiN (111) films sit on an amorphous nitride layer with low impurity concentrations. The films superconduct with T c = 5.4 K, and coplanar waveguide resonators are fabricated with a small center width of 6 μ m that demonstrate single-photon quality factors approaching 1M and high-power quality factors over 5M without observing saturation. [ABSTRACT FROM AUTHOR]

A silicon photonic crystal waveguide based design of a highly-compact transverse-magnetic pass polarization filter has been proposed in this paper. The device utilizes both the index guiding and bandgap property simultaneously to realize its operation as a polarizer. Optimizations of different device-parameters, such as the radius of the holes, width, thickness, and length of the waveguide, have been performed for attaining its paramount performance. A small waveguide length, in the order of 5 μ m, has shown a high extinction ratio, i.e., 45 dB, at the wavelength of 1550 nm. A uniform bandwidth of ≈ 120 nm is observed, beyond the extinction ratio of 40 dB, along with a remarkably low insertion loss, i.e., ≈ 0.6 dB. Investigations are also performed to evaluate performances of the polarizer under possible fabrication disorders, which depicts a sustained performance up to at least a random fabrication disorder of 30 nm. These merits make the polarizer suitable for applications in densely integrable photonic integrated circuits. [ABSTRACT FROM AUTHOR]