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Multiple-in-multiple-out (MIMO) technique is one of the critical techniques for 5G and beyond. For supporting the beamforming configurations of 5G and beyond, millimeter-wave (mm-wave) phased arrays will be adopted, resulting in high requirements of the signal alignments among the arrays.

This article presents a full-wave method to characterize lossy conductors in an interconnect setting. To this end, a novel and accurate differential surface admittance operator for cuboids based on entire domain basis functions is formulated. By combining this new operator with the augmented electric field integral equation, a comprehensive broadband characterization is obtained. Compared with the

The solution of highly nonlinear inverse scattering problems is addressed. An innovative multiresolution microwave imaging technique, which leverages on the profitable integration of the contraction integral equation for inversion (CIE-I) and the iterative multiscaling approach (IMSA), is proposed. Thanks to the joint exploitation of the features of the CIE-I formulation and the IMSA, the arising IMSA-CIE-I

Advances in semiconductor devices have allowed researchers to explore temporal modulation as a means to achieve nonreciprocity. This is of practical importance, since nonreciprocity is often desired in electronic systems that are incompatible with the integration of magnetic materials. Recently, $N$ -path networks, a class of electronic systems, whose behavior was first introduced in the 1950s, have

To alleviate the nonuniform error distribution and slow convergence caused by the uncertainty of sample selection in the training process of artificial neural networks, a semisupervised radial basis function neural network (SS-RBFNN) model with a new sampling strategy is proposed for parametric modeling of microwave components in this article. After evaluating the current training performance, the

In this article, starting from full-wave partial differential equation (PDE)-based Maxwell’s equations where $\mathbf {E}$ and $\mathbf {H}$ are coupled, we derive a closed-form model of the inverse of Maxwell’s system of equations in the physical layout of an integrated circuit, package, and board. In this model, we decompose the inverse rigorously into $R$ , $C$ , $L$ , and full-wave components,

A compact and broadband circular TE 01 -mode oversized deformed waveguide bend for high-power transmission line is proposed in this article. In order to obtain a circular TE 01 mode with high purity output, a deformed waveguide structure, entitled quad-polar waveguide, which can destroy the degeneration between the TE 01 and TM 11 modes and weak mode conversion inside waveguide bend is introduced.

A novel reconfigurable negative group delay (NGD) circuit based on branch-line coupler is proposed in this article. It consists of two branch-line couplers that are connected by two varactors with different capacitance values. By simply adjusting the capacitance values, both the transmission gain/loss and group delay (GD) values of the proposed circuit can be independently adjusted as desired. Full

This article discusses on the measured third-order intermodulation (IMD3) products and third harmonics (H3) appearing in a set of six different solidly mounted resonators (SMR) and bulk acoustic-wave (BAW) resonators with different shapes and stack configurations. The discussion is supported by a comprehensive nonlinear distributed circuit model that considers the nonlinear effects potentially occurring

A microwave device able to detect differential-mode to common-mode conversion (or vice versa) in a four-port balanced circuit is proposed. For mode conversion detection, the balanced circuit should be fed by a differential-mode signal, generated by means of a rat-race balun from a single-ended signal. By connecting the pair of output ports of the balanced circuit under test to one of the two pairs

This article utilizes a topology optimization approach to design planar multilayer transitions between substrate integrated waveguides (SIWs) and rectangular waveguides (RWGs). The optimization problem is formulated based on the modal field analyses and Maxwell’s equations in the time domain solved by the finite-difference time-domain (FDTD) method. We present a time-domain boundary condition based

Resistive-wall impedance constitutes a significant percentage of the total beam-coupling impedance budget of an accelerator. A number of different reduction techniques have been proposed during the years depending on the specific applications, ranging from higher order modes damping to solutions entailing high electrical-conductivity coatings of the pipe. This article investigates the use of metamaterial-based

This article presents a method for analyzing the coupling between two adjacent substrate-integrated waveguides (SIWs) sharing a common row of metallic cylinders, which is based on the concept of equivalent circuit and wavenumber calculation. When the specific sizes of two adjacent SIWs are known, the scattering parameters of the shared common row of metallic cylinders can be derived, and the equivalent

A Ku / Ka -band oversized waveguide bend, transmitting the power of TE 01 mode at Ka -band and TE 11 mode at Ku -band, is designed for the high-power transmission line. To suppress the generation of parasitic modes, a waveguide bend based on the elliptical waveguide is used to minimize the coupling capacity between the operating modes and the undesired modes. The mode coupling rules inside the elliptical

Mushroom-type electromagnetic bandgap (EBG) structures are known to operate as high-impedance surfaces at low-frequency bands. They are broadly used in the microwave regime. However, one of the main drawbacks of mushroom-type EBG structures is their narrow bandwidth. In this article, we propose a mushroom-type EBG structure with glide-symmetric edge vias to increase the operational bandwidth. This

In this article, a novel and efficient ultra-wideband power-combining method over K (18–26 GHz) and Ka (26–40 GHz) band is presented. Ridge waveguide power combiners and contactless transition between ridge waveguide and double microstrip lines will be used in this method. By using this method, a 16-way power combiner system is designed to work in the bandwidth of 18–40 GHz through 3-D electromagnetic

High-performance microwave and millimeter-wave filters’ design is a challenging task because the filter characteristic is rather sensitive to the variation of geometric dimensions and electrical sizes. A common practice in filter design is to optimize the design variables starting from a set of initial values. However, if the initial values are not sufficiently close to the optimal solution, the optimization

We propose an impedance-matching technique for metasurfaces generating evanescent fields with complex free-space impedance for subwavelength focusing. The proposed technique is mandatory for the subwavelength focusing far beyond the diffraction limit. First, we theoretically show the fact that the wave impedance becomes a complex number due to the generated evanescent fields and give an explicit form

A new, frequency-domain, behavioral modeling methodology for radio frequency (RF) power transistors, based on canonical section-wise piecewise linear (CSWPL) functions, is presented in this article. The basic theory of the proposed model for fundamental, harmonic, and dc responses is provided within. Compared with the existing nonlinear behavioral models, which require tables of coefficients to account

In this article, a class of improved Schiffman phase shifters with two C-section coupled lines separately operating in the first and second phase periods is presented and analyzed. Theoretical model and closed-form synthesis formulae are utilized to analyze the phase performances of the proposed phase shifters, which reveals significant differences compared to the phase shifters solely operating in

In this article, a novel topology is proposed to design a class of power dividers with the simultaneous realization of wideband power division and port-to-port isolation. On the one hand, in order to achieve a wideband power dividing response, two wideband filtering branches, including multimode resonators and parallel-coupled lines, are formed to replace the quarter-wavelength impedance transformers

An analytic broadband design method for four-port N-branch branch-line couplers with outputs terminated by arbitrary impedances is given. An alternative, more practical design method has also been included, which avoids impedance discontinuities in the branches and retrieves the outputs-in-quadrature property lost in the asymmetrization. The doubly asymmetrical couplers so obtained are then used in

This article presents a type of bandpass filter (BPF)-integrated single-pole double-throw (SPDT) switch using the frequency selective star-junction matching circuit and the switched magnetic coupling (SMC) technique, i.e., the lowpass phase shifter (LP-PS) and the quasi-elliptic lowpass filter (QE-LPF) with specified phase shift. Firstly, a high selectivity third-order BPF-integrated single-pole single-throw

In this article, we present the first demonstration of distributed and symmetrical all-band quasi-absorptive filters that can be designed to arbitrarily high orders. The proposed quasi-absorptive filter consists of a bandpass section (reflective-type coupled-line filter) and absorptive sections (a matched resistor in series with a shorted quarter-wavelength transmission line). Through a detailed analysis

Techniques of common-mode (CM) noise absorption have been developed in recent years, but very few of them can achieve CM bidirectional absorption. This article proposed a novel circuit architecture that can provide bidirectional CM noise absorption theoretically, meaning that the circuit can absorb CM noises from both sides of differential channels. The essential concept is to design the even–even

In order to compensate for amplitude inconsistencies of components and circuits, the equalizer has been proposed and introduced. In the previous reports, the theory of equalizer is mainly based on the resonant circuit. In this article, the substrate integrated waveguide (SIW) equalizer fabricated on a ceramic substrate with surface resistance, operating in a millimeter- wave band, is presented first

In this article, for the first time, a novel four-port coupler with reconfigurable multifunctions of filtering rat-race coupler (FRC), filtering branch-line coupler (FBC), and conventional single-ended two-port multipole bandpass filter (BPF) is proposed. It simply consists of four varactor-loaded stepped-impedance resonators that are arranged symmetrically. Through appropriate coupling-type (electrical

A new type of wideband single-ended-to-balanced (SETB) power divider (PD) is presented. The design achieves high level and extended frequency range of common-mode (CM) suppression. Slotline-to-microstrip transitions are essential parts of the design, for the CM signals will be terminated in the slotline and thus will be rejected. Slotline resonators are used to provide multiple resonances which form

This article presents a systematic procedure aimed to design continuous profile stopband filters assembled with empty substrate integrated coaxial lines. The coaxial filter is made of five low-cost substrate layers, where the central boards contain the filter profile. This structure exhibits unimodal TEM operation over a wide frequency band, it is not dispersive, it is shielded and cannot be interfered

This article presents a 9.9–12.45 GHz voltage-controlled oscillator (VCO) designed in 0.12 $\mu \text{m}$ SiGe BiCMOS with a focus on achieving the lowest possible phase noise using only a single core and maintaining the recommended Vdd of the technology. The oscillator consists of a cross-coupled design utilizing a transformer-coupled resonant tank, which takes advantage of tank parasitics to create

A novel trombone topology has been introduced for achieving controllable true time delay. The prominent aspect of the proposed topology is the ability to provide discrete variable delay with minimum insertion loss variation with delay settings. Furthermore, the effects of source impedance, output load, and line-terminating loads’ impedance mismatch on group delay variation are theoretically investigated

A high-precision delay chain circuit integrated in a 0.18- $\mu \text{m}$ CMOS technology working in the frequency bandwidth of 8–18 GHz has been designed and tested. The designed delay control integrated circuit with 5-bit delay control provides a maximum delay of 125 ps and has a delay resolution of 3.9 ps. Measured delay error of the fabricated chip is less than 9.3%, making it a considerably accurate

Spread-spectrum clocking (SSC) is an active solution to attenuate electromagnetic interference (EMI) in Gb/s serial communication systems by slightly modulating the phase-locked loop (PLL) output clock frequency. This article presents a phase-compensated spread-spectrum clock generator (SSCG) with the state-of-the-art EMI reduction and clock rms jitter performance. A 32-slice scaled resistor-based

This article presents a 3.25 GS/s fourth-order programmable analog finite impulse response (AFIR) filter for flexible discrete time analog signal processing (DT-ASP). For wide application of the proposed AFIR filter, it is designed for full bandwidth utilization up to the Nyquist rate, programmable via the multiplier coefficient set. In this implementation of the FIR function, split-capacitive DACs

This article presents a compact, narrowband and highly selective filter with flattened passband response using TM dual-mode cavities. Indispensable passband flatness as well as very high selectivity was achieved using TM dual-mode resonator filter and equalizer. The design of an eighth-order filter is presented with the experimental results at 10.97 GHz and to satisfy the passband flatness requirements

This article presents a technique based on a modified complementary split-ring resonator (CSRR) to detect angular displacement and direction of rotation with high resolution and sensitivity over a wide dynamic range. The proposed microwave planar sensor takes advantage of the asymmetry of the sensor geometry and measures the angle of rotation in terms of the change in the relative phase of the reflection

In this article, a new approach is proposed for the measurement of the uniaxial anisotropic dielectric constant of different planar samples by means of a single sensor. The sensor is based on a couple of straight-line coupled resonators in microstrip technology that can be excited in odd and even propagation modes. This sensor is designed on an isotropic substrate at the design frequency. Due to the

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This mini-special issue of the IEEE Transactions on Microwave Theory and Techniques includes seven expanded articles from the sixth IEEE MTT-S International Wireless Symposium (IEEE IWS 2019) held on May 19–22, 2019, in Guangzhou, China.

This article proposes a new method to realize a low-profile broadband absorber. The unit cell of the proposed absorber consists of two layers: a lossy layer with four rotationally symmetric bent metallic strips embedded with two chip-resistors, which is modified from a doubly fed dipole antenna, and a metallic ground separated from the lossy layer by an air spacer. Three resonant modes of the metallic

This article designs and analyzes LC injection-locked frequency dividers (ILFDs) using dual-resonance LC resonator. The ILFD consists of two single-resonance LC -tank capacitive cross-coupled sub-ILFDs operating at 3.7 and 5.1 GHz, respectively, and the two sub-ILFDs are coupled by the electric field through a pair of metal–insulator–metal (MIM) capacitors. The die area in the Taiwan Semiconductor

A high-isolation eight-way power combiner is proposed in this article that is constructed by cascading three stages of power combiners in series. Its high isolation and low return loss are realized by means of lumped isolators, an isolated side network, and a resistive septum. The eight-way power combiner is basically a 17-port mode network, consisting of eight input ports, eight matching ports, and

In this article, we propose a circuit model for designing the switchable filtering circuit with reconfigurable functions between a single-pole quad-throw (SPQT) filtering switch (State 1) and a four-way filtering power divider (State 2) without additional switchable impedance matching network (IMN). The proposed circuit model can be utilized as the feeding network of a switchable directive and omni-directional

A class of symmetrical multilayered reflectionless wideband bandpass filters (BPFs) with shunt/in-series resistively terminated microstrip lines are presented. Based on a wideband microstrip-to-microstrip vertical transition and two shunt resistively terminated multisection microstrip lines, wideband BPFs that feature broadband reflectionless behavior are first discussed. Subsequently, by increasing

This article presents and analyzes a wide-locking range divide-by-5 injection-locked frequency divider (ILFD) manufactured in the TSMC 0.18- $\mu \text{m}$ processes. The ILFD uses the balanced injection method and uses the pure harmonic mixing approach at low injection power, and it is designed with an RLC dual-resonance resonator. The harmonic mixer relies on the self-generated second harmonic, which

The state-of-the-art wireless positioning and wireless charging using magnetic coupling designed for wireless capsule endoscopy (WCE) require different magnetic field distributions and system structures. Due to the space and weight constraints of WCE, designing a system that achieves wireless positioning and wireless charging simultaneously becomes an emerging problem. A switched field structure based

Multiple-in–multiple-out (MIMO) technique is one of the critical techniques for 5G and beyond. For supporting the beamforming configurations of 5G and beyond, millimeter-wave phased arrays will be adopted, which results in high gain (directional beams) and improved link margin between the transmit and receive systems.

This article presents the analytical computation of full-wave partial elements modeling magnetic materials in the framework of the partial element equivalent circuit method. Assuming an orthogonal mesh, the free-space Green’s function is expanded in Taylor’s series. The resulting series expansion coefficients occurring in magnetic material modeling are computed analytically up to the second order.

This article presents the design and fabrication of low-loss, -weight, and -cost, modified Butler matrix in groove gap waveguide technology at W-band, implemented by additive manufacturing. The design, simulations, and measurements of each of the elements that conform to the modified Butler matrix are presented. The proposed modified Butler matrix is asymmetric and oriented to an easy assembly with

In this article, a novel tunable attenuator based on graphene is proposed. It consists of a coupled microstrip line (CMSL) and two graphene-covered gaps in MSLs. By utilizing a biased voltage, the surface impedance of graphene can be tuned, and then, the reflective coefficient at two ports of the coupler can be correspondingly adjusted; therefore, the performance of the attenuator can be modified.

A great challenge in power/RF electronics has been achieving integrated magnetic inductors with high quality factor ( $Q$ -factor) and high inductance density at gigahertz frequencies. In this article, integrated solenoid magnetoelectric inductors based on FeGaB/Al 2 O 3 multilayer as the magnetic core are designed to operate at high gigahertz frequencies, high $Q$ -factor, and inductance tunability

Ideally, the orthogonal port can be effective to eliminate the TE 102 /TE 201 spurious passband of a fundamental substrate integrated waveguide (SIW) filter using the orthogonality. However, it was not feasible in practical applications because the orthogonality of TE 102 /TE 201 is deteriorated by the orthogonal port. Here, we propose an approach to repair the orthogonality which makes the practical

A technique for the characterization of a class of coaxial-line-to-waveguide adaptors, which is based on the eigenvalues and eigenvectors of their scattering matrix, is presented. The adaptor comprises a number of coaxial-line ports symmetrically distributed on the surface of the waveguide. This allows for the independent excitation and measurement of different propagating modes in a multimodal operation

This article demonstrates the feasibility of a novel waveguide dual-mode two-way power divider that is based on an evolved junction having a dedicated T-shaped central matching element (scatterer). This scatterer, with matching sections facing all three ports, provides equal power division and routes the two TE 10 /TE 01 orthogonal modes of a square waveguide toward the corresponding output ports.