Here we consider a disordered system of interacting quantum dots—nanostructures with applicability in systems ranging from quantum computing to next-generation displays. Quantum dots facilitate absorptive and emissive processes at frequencies over timescales independent of those in the incident radiation; by treating the system semiclassically we maintain the discrete dynamics inherent to quantum objects without resorting to second quantization to describe electromagnetic fields. Our solution proceeds via determination of source wavefunctions through evolution of the differential Liouville equations and evaluation of radiation patterns through integral equation techniques. We employ a highly-tuned predictor-corrector integration scheme to advance the source wavefunctions in time; the polarizations that arise then serve as sources within the integral equations that we use to propagate the field. This coupled solution produces a description of both the quantum and electromagnetic dynamics at each timestep giving rise to lasing effects, non-linear propagation, coupled Rabi oscillations, and other optical phenomena.

We discuss a new electromagnetic particle-in-cell algorithm for the simulation of Maxwell-Vlasov equations on unstructured grids. The use of discrete exterior calculus and differential forms of various degrees enables numerical charge conservation from first principles, down to the numerical precision floor. In addition, energy conservation is obtained via a symplectic field update. The algorithm is illustrated for the modeling of high-power microwave devices based on Cerenkov radiation driven by relativistic plasma beams.

Wireless communications are expected to take place in increasingly complicated scenarios, such as dense urban, forest, tunnel and other significant cluttered environments. A key challenge emerging is to understand the physics and characteristics of wireless channels in complex environments, which are critical for the analysis, design, and application of future mobile and wireless communication systems. The objective of this work is to investigate high-resolution, high-performance computational algorithms for extreme-scale channel modeling in real-world environments. The system-level large scene analysis is enabled by the novel, ultra-parallel algorithms on the emerging exascale high-performance computing (HPC) platforms. The results lead to much greater channel model resolution than existing deterministic channel modeling technologies. All relevant propagation mechanisms are accounted for in first-principles. Such a modeling framework will be critical to gaining fundamental physics of wireless propagation channels in real-world scenarios.

A rigorous yet computationally efficient three-dimensional nu-merical method has been proposed based on modified alternat-ing-direction-implicit (ADI) finite difference time domain meth-ods (FDTD) and it has the capability of modeling the eccentric property of magnetic material being anisotropic, dispersive or nonlinear. The proposed algorithm solves Maxwell’s equations and LLG equations simultaneously, requiring only tridiagonal matrix inversion as in ADI FDTD. The accuracy of the modeling has been validated by the simulated dispersive permeability of a continuous ferrite film with a 1.5 um-thickness, using a time-step size 104 times larger than the Courant limit. The permeability agrees with the theoretical prediction and magneto-static spin wave modes are observed. Moreover, electric current sheet radia-tors close to perfect electrical conductors loaded with 2 um-thick ferrite films are simulated, which exhibit a radiation efficiency 20dB higher than conventional dipole antennas on the same scale.

Recently, keen interest has been shown in using microwaves as the heat source for materials manufacturing processes that rely on sintering. We present here a two-dimensional model of microwave sintering that accounts for the chain of physical phenomena that influence the process (i.e., electromagnetics, heat transfer and mechanical deformation), including the dependence of dielectric and thermal properties on the temperature and relative density of the sample. The model relies on finite difference methods for the electromagnetic and thermal models, and a Master Sintering Curve to construct the inverse function for density evolution, and is presented together with its computer implementation as a series of Python scripts, which runs quickly and whose accuracy is demonstrated via comparison to experimental results from literature.

This paper presents a detailed analysis of thermal coupling and self-heating effects in highly integrated wireless transmitters. A MIMO transmitter prototype consisting of two closely integrated power amplifiers was built and modelled through microwave and thermal characterizations. The thermal behavior was extracted using FEM software and modelled with an equivalent RC net-work. The PA model was obtained experimentally using a pulsed setup. An RF-thermal simulator was developed and used with the models to predict joint thermal and electrical behavior. Measurements with modulated communication signals were done and compared with the simulator to demonstrate its feasibility for analysis of thermal effects in highly integrated transmitter applications.

A new methodology for the prediction of the oscillator phase noise under the effect of an interference signal is presented. It is based on a semi-analytical formulation in the presence of the noisy interferer, using a realistic oscillator model, extracted from harmonic-balance simulations. The theoretical analysis of the phase process enables the derivation of key mathematical properties, used for an efficient calculation of the interfered-oscillator phase noise spectrum. The resulting quasi-periodic spectrum is predicted, as well as the impact of the interferer phase noise over each spectral component, in particular over the pulled oscillation frequency. It is demonstrated that, under some conditions, the phase noise at this component is pulled to that of the interference signal. Resonance effects at multiples of the beat frequency are also predicted. The analyses have been validated with experimental measurements, obtaining an excellent agreement.

Abstract— Distributed synchronization of sensor networks can be achieved by coupling the oscillator signals of the sensor nodes. Previous works describe the coupling effects in an idealized man-ner, with constant scalar coefficients. Here a realistic analysis of the coupled-system dynamics is presented for the first time to our knowledge, taking into account the antenna gains and propaga-tion effects on the amplitude and phase values of the equivalent current sources, injecting the oscillator elements. The new formu-lation provides the synchronized oscillation frequency and ampli-tude and phase distributions of the coupled system. Distinct oscillation modes, with different phase shifts between the oscilla-tor elements, are identified, associated with the system symmetry. The stability properties of these modes change with the distance between the oscillator elements. The possibility to impose in-phase operation by tuning of the oscillator elements is demon-strated. Good agreement is obtained between simulation and measurements.

We examine the problem of evaluating and optimizing the linearity of a FET device, with application to carbon- nanotube (CNT) FETs. We begin by noting that conventional linearity criteria, such as input and output intermodulation intercept points, are poor figures of merit for such devices. Instead, we propose dynamic range as the figure of merit and use a simple, unilateral FET equivalent circuit to develop insight into its optimization. To do this, we derive expressions for the dynamic range of a FET described by that equivalent circuit. This exercise identifies criteria for optimizing linearity and comparing the linearity of dissimilar devices. Measurements of inherent linearity are presented, and we show that CNT devices are significantly more linear than modern microwave FETs.

In this paper, a simulation methodology is presented that takes carrier dynamics into account, disallowing instantaneous changes in substrate carrier concentrations, and providing more accurate estimations of HD components. Using this method, harmonic distortion (HD) components introduced in CPW lines on Si-based substrates are simulated. The results are compared to measured HD components over a wide range of bias points and at three fundamental frequencies from 900 MHz to 4 GHz. It is shown that carrier relaxation times are of first importance for understanding the HD introduced by Si-substrates at RF frequencies and above. Furthermore, characteristic dips in the HD components, are evaluated and shown to be tightly linked to the position of the device’s DC bias voltage relative to the substrate’s flatband voltage. The new simulation tool is also capable of capturing these typical dips in the HD curves, and provides physical insight into the reasons behind their existence.

The self-heating and charge trapping effects are implemented in surface-potential (SP) based large signal model of AlGaN/GaN HEMTs in this paper. The self-heating effect (SHE) is incorporated into nonlinear current model by embedding temperature increment into free-carrier mobility model. Moreover, the dispersion due to trapping effect is modeled through an effective gate-source voltage based methods. The experimental results show that the proposed model can accurately predict the static (DC) and pulsed-gate-and-drain IV (PIV) characteristics of the device over a wide bias. And the small-signal and large-signal behavior is also verified with good accuracy.

This paper addresses a novel approach account for trapping effects in the large-signal description of GaN HEMTs. Instead of relying on an internal effective gate voltage, which is not very intuitive, it is investigate how the Chalmers (Angelov) model parameters are altered by trapping. It is verified that such an approach enables reliable load-pull prediction over a wide range of drain bias voltages. In addition, appropriately scaled parameters are shown to allow for a good estimation of large-signal performance even if the model itself misses a dedicated trapping description.

A simple procedure for extracting parameters of a bias-dependent trap model for GaN and GaAs is presented. The extraction is achieved based on a mapping of the steady-state trap-center potential for a representative range of the bias voltages. The circuit model of trapping is verified in the process. The time constant for emission is also extracted. It is demonstrated that the model is able to predict device response and time constants in both capture and emission states. Bias-dependence of trapping and associated time constants is successfully modeled.

This paper presents a temperature dependent empirical model for GaN HEMTs with the consideration of charge trapping and self-heating effects. A new 13-element drain current source (Ids) model is proposed. The current dispersion deduced by trapping and thermal effects is generally modeled by Taylor expansion, and for the first time, the dispersion related coefficients are rigorously derived to be the combination of analytical Ids functions. The Ids model is manifested by the accurate prediction of massive measured PIVs with various quiescent biases and power dissipation. The large signal model is implemented in Advanced Design System (ADS), and the simulations of both DC and RF characteristics well agree with the measurements

This paper presents a new compact electrothermal model for GaN high electron mobility transistors (HEMTs). An analytic and succinct expression for the drain current Ids is acquired by combining surface potential based method and channel division method. Self-heating effects are described in the model by intro-ducing an empirical expression for the critical electric field Ec as a function of temperature and gate voltage. The presented I-V model can accurately fit DC measurements. Furthermore, good agreement between RF simulations and measurements can be achieved by substituting the I-V model in this paper for the original Ids module in a compact large-signal model.

An artificial gradient-index lens for phase correction of a horn antenna in the Ka-band is presented. By introducing a gradient of the geometric features in the single layer fishnet unit cell, a phase variation between -180 and +180 degress can be obtained. The relation between the geometric dimensions, phase- and amplitude distribution is presented. Furthermore, phase-correction and resulting improved radiation pattern is demonstrated at 27.5 GHz and evaluated by nearfield measurements making the presented single layer fishnet a good candidate for artificial lenses with low weight and low fabrication costs.

In this paper, the distinction between Zenneck waves and surface plasmon polaritons is illustrated. The surface plasmon needs to be excited by an electron beam which can be effectively generated by a source of electrons or a quasiparticle like an evanescent wave which tunnels through the medium and thus excites the electrons. The surface plasmon propagates at the interface between a metal and a dielectric at petahertz frequencies when the conditions are right. For the Zenneck wave, the evanescent transverse field components do not change appreciably with frequency as the Brewster phenomenon is independent of frequency, whereas for a surface plasmon, with an increase of the frequency, the wave is more closely coupled to the surface. The Zenneck waves are produced at the zero of the reflection coefficient of an incident TM wave on an air-dielectric interface whereas the surface plasmons are produced when the reflection coefficient is infinite.

Discrete Dipole Approximation (DDA) is presented as a simulation tool for predicting the radiation properties of uniform and tapered Leaky Wave Antennas. A comparison between this method and full wave simulation demonstrates the accuracy of the presented technique. This technique is especially attractive since it allows us to simulate and design LWAs with unusual tapering to achieve desired beamwidth and sidelobe level while maintaining steering capabilities.

A 2D periodic leaky-wave antenna consisting of a periodic distribution of rectangular patches on a grounded dielectric substrate, excited by a narrow slot in the ground plane, is studied here. The TM0 surface wave that is normally supported by a grounded dielectric substrate is perturbed by the presence of the periodic patches to produce radially-propagating leaky waves. In addition to making a novel microwave antenna structure, this design is motivated by the phenomena of directive beaming and enhanced transmission observed in plasmonic structures in the optical regime.

Instability has been a major problem in FDTD subgridding methods. Reciprocity has been proposed to overcome the problem but with limited success in producing a symmetric system without compromising accuracy. In this paper, we algebraically derive an FDTD subgridding operator that is theoretically symmetric positive semi-definite, independent of the grid ratio and whether the grid is 2- or 3-D. Such an operator has only nonnegative real eigenvalues, and hence the stability of the resulting explicit time marching is guaranteed. We also translate this operator from its matrix form to the original FDTD difference equations to show how the fields involved in the subgridding are generated to obtain a symmetric system without compromising accuracy. Numerical experiments have validated the accuracy and stability of the proposed subgridding method.

This paper introduces a novel and efficient technique for the computation of high-order, multi-parametric sensitivities, over a broad frequency range, with FDTD. Based on the multi-complex step derivative approximation, it is free of the well-known subtractive cancellation errors that are associated with finite-difference methods. It can be directly embedded in FDTD, running in parallel with its time-stepping loop, to calculate first and higher order partial derivatives of field components. For example, the full Hessian matrix of output functions of interest, such as scattering parameters, with respect to multiple design variables, can be computed in a single FDTD simulation.

A new method for high precision extraction of per-unit-length inductance and resistance in the multi-conductor transmission lines (MTLs) is presented. The approach is based on higher-order geometrical representation of the MTL cross-section followed by higher-order method of moment discretization of a novel surface single-source integral equation. Through comparison against the analytically available solutions the method is shown to achieve 6 digits of precision in the extracted MTL's resistance (R) and inductance (L) using moderate computational resources. The proposed approach paves a way for numerically inexpensive characterization of MTLs of arbitrary cross-sections with analytic-like quality.

This paper presents a domain decomposition based hybrid finite element boundary integral method for solving electromagnetic radiation and scattering problems. The method employs a second order Robin’s transmission condition to unite the finite element method and boundary element method at the truncation surface, leading to rapid convergence of domain decomposition iterations. Furthermore, the method provides a systematic approach to hybridize various electromagnetic solvers into one powerful hybrid solver. In this work, we have combined finite element method, method of moments, and asymptotic high frequency methods such as physical optics and shooting and bouncing rays. A one-way domain decomposition method will also be presented to provide an alternative fast and efficient solution.

In this work we present the Correlation Transverse Wave Formulation (CTWF) method for direct computation of the auto- and cross correlation functions (ACFs and CCFs) of stationary stochastic electromagnetic fields. The Transverse Wave Formulation (TWF), in performing a modal expansion of the Electromagnetic Fields in the homogeneous parts of the calculation domain and solving the near field continuity on both sides of the circuit surfaces, provides a direct derivation of the ACFs and CCFs without hypothesis on the structure of radiated fields.

Time reversal (TR) techniques have been introduced for many applications in acoustics, seismology, medical imaging, electro-magnetics, and so on. One of the applications is source locating in a time-invariant environment. By performing the TR process, temporal and spatial focusing occurs at the original source loca-tion and consequently the source locations are identified. In this paper, we propose a new TR method which allows the location identifications of narrow-band sources and moving sources which have not been considered. The proposed method is built on the conventional time-reversal method and therefore retains the simplicity and robustness of the conventional TR technique. Nu-merical examples are given to verify the effectiveness of the pro-posed method.

Look-up table behavioral models (i.e. X-parameters, Cardiff model), input drive |A11| referenced, extracted directly from measurement data, provide an accurate non-linear CAD modeling solution. Typically, formulated, like s-parameters, in the travelling wave (A-B) domain, since these waves can be directly measured and controlled in the high frequency domain. However, if formulated in the admittance (I-V) domain they would provide a more robust MMIC design modelling solution supporting the capability of width and frequency scaling. Presently, no technique has been presented that allows for the extraction of admittance behavioral models directly from load-pull measurements. Previous solutions have all involved complex indirect procedures based on using an extracted A-B domain behavioral model and CAD simulations using voltage sources. In this paper, a new extraction approach is presented which, by including the influence of variable V11, allows for direct extraction of admittance behavioral models. This approach has been validated on GaN devices.

This paper presents a novel behavioral model of RF transistors under periodic stimulus that is mathematically equivalent to frequency domain Poly-Harmonic Distortion (PHD) models but is defined instead in the time domain. Given a fixed fundamental frequency for a periodic stimulus, a time domain PHD (TD-PHD) model that describes this periodic behavior consists of two nonlinear functions, each describing the large-signal response at one of the two ports of the RF transistor. In this model, the response at each port at any given time is a nonlinear time-invariant function of the stimulus at both ports throughout its entire RF period. Using a two-port hybrid passive/active multi-harmonic load-pull measurement setup, a 10W GaN packaged transistor biased in class AB is measured with a Nonlinear Vector Network Analyzer (NVNA). The predictive performance of the extracted model is validated against a power amplifier design that uses this RF transistor.

Power Amplifiers can either be designed directly from load-pull data or using CAD software with embedded nonlinear models. Both approaches have advantages and disadvantages and their own range of applicability. Availability of reliable transistor mod-els is usually the main factor to decide which approach to be followed. This paper presents a double pulse S-parameter meas-urement system that enables the extraction of current and charge conservative models of GaN HEMT devices. The obtained charac-teristics were used to predict the transistor load-pull curves which finally led to a RF power amplifier design. The very good agree-ment obtained between the output power and efficiency load-pull predictions, and their corresponding PA measured values, attest the quality of the extracted current and charge data, using the developed system.

A knowledge-based neural network (KBNN) modeling and analysis method is presented for determining junction temperature, Tj, and thermal resistance, Rth, from simple electrical measurements of HBTs. The method retains sound physical principles of classical approaches but provides significant additional practical benefits for modeling and prediction based on the mathematical properties of neural networks when endowed with additional a priori “knowledge”. The method returns explicit, infinitely differentiable approximations for Tj and Rth as functions of ambient temperature, Tamb, and power dissipation, Pdiss. The method enables reliable predictions of Tj over a very wide range (e.g. 25C to 250C) by working with any complete set of experimental variables. The method also provides an automatically trained, measurement-based DC electro-thermal transistor model as a function of bias and temperature.

A measurement based Error-Vector-Magnitude (EVM) extraction and modeling is proposed to obtain a least squares estimate of the EVM for a class of modulted excitation signals sharing a common probability density function (pdf) and Power Spectral Density (PSD). The method splits the influence of the linear dynamic and the nonlinear distortion on the EVM. The dependence of the EVM on the input signal power is extracted and modeled. The inlfuence of the measurement noise on the measured EVM is compensated, reusltling in a clear improvement of the measured quantity. The results are validated on measurements obtained by a VSG-VSA measurement setup.

In this paper, large-signal operation of IQ-mixers is studied using a vector-corrected four-port measurement setup with wideband modulated signals as stimuli. The measurement setup presents unique characterization possibilities since it has two ports at low/baseband frequencies and two ports at RF, making it ideal for characterization of frequency-translating devices such as mixers. A commercial upconverting IQ-mixer is studied, with the I and Q input signals residing at incommensurate frequency grids, enabling separation of the nonlinear distortion generated in the I and Q branches. Frequency-domain and time-domain measurements reveal imbalances between the I and Q branches in terms of conversion gain and nonlinear distortion. It is also shown for the same mixer that operating the I and Q branches concurrently has limited influence on both conversion gain and nonlinear distortion, compared to non-concurrent operation.

A method for emulating antenna array coupling effects, based on active load-pull, to present time-varying impedances to power amplifiers (PA) is presented. An entire array, given identical elements, can be emulated using a single device-under-test (DUT). The method is demonstrated and verified by studying two scenarios, where the resulting adjacent channel power ratio (ACPR) and error-vector magnitude (EVM) are given as function of delay and coupling for a 6W GaN PA. Differences in ACPR and EVM can be attributed to time-variant load impedances.

This paper discusses the implementation of a solution to study over the air 5G Massive MIMO antenna transmitter arrays. The proposal is based on a multi-sine approach similar to what is being done to explore nonlinear devices. The approach followed is supported on a multi-sine waveform where each element on the array is excited by two tones, being one the common local oscillator, and the other a modulation with a single sinusoid (called a tickle tone). Since each element in the antenna is fed by a different modulated waveform, the overall structure can be evaluated remotely using a simple probe followed by a Vector Signal Analyser. By measuring each of the sines in the receiver stage, the change in amplitude and phase can give an initial approach to each of the transmitter element. The implementation of this solution will be discussed throughout this paper.

In this paper, microstrip bandpass filters using fragment-type coupling structure based on multi-objective optimization are proposed for the first time. The fragment-type coupling structure allows the design of bandpass filters with improved characteristics. In particular, it can implement filters with desirable upper stopband performance and reduced occupation area. The design of fragment-type coupling structure can be implemented automatically by multi-objective optimization searching with several design objectives characterizing bandpass filters. For demonstration, three filters are designed based on the proposed fragment-type coupling structure. Compared with the conventional parallel coupled-line filter, the upper stopband performance is improved due to the extra transmission zeros generated by fragment-type coupling structure, and the minimum efficient circuit area is reduced by 61.4%. The measurement results show good agreement with simulation.

A new method is introduced to construct models for systems composed of a cascade of transmission lines tapped by lumped elements including multiple reflections. This method does not limit the reflections in their magnitude or their position in the structure under study. A model suite of increasing model complexity and modeling power is used to provide accurate yet parsimonious models for system of increasing complexity. Accurate models are obtained from simulated and measured data over a wide bandwidth with a parsimonious number of model parameters.

A novel eigenmode-based neural network (NN) for a fully automated design of microstrip bandpass filter (BPF) is proposed in this paper. The NN is now useful for BPF designs because a part of design procedure is automated. However, even though the design time is reduced by the NN, an extra structural optimization is still needed as post processing, since a passband response is degraded by undesired but intrinsic cross couplings that are not considered in filter circuit synthesis. No fully automated BPF design techniques have not been developed yet. In the proposed method, the NN is constructed based on the coupling matrix of transversal array filter, which can evaluate all the couplings between resonators as eigenmodes appearing in BPFs. As a test example, a third-order parallel-coupled microstrip BPF is automatically designed by using the proposed NN. The effectiveness of the proposed approach is verified through numerical and experimental tests.

In this paper, we discuss multi-objective design optimization of planar inductors using surrogate modeling techniques. The goal is to identify the best possible trade-offs between the quality factor of the inductor and its size while maintaining a required value of the inductance at a given operating frequency. The design problem is formulated as a mixed-integer task involving geometry parameters as well as the number of inductor windings. The initial Pareto front is found by optimizing a data-driven surrogate of the structure at hand, further refined by means of response correction techniques. Our considerations are illustrated using a 3.5-nH spiral inductor implemented in 65-nm CMOS technology.

a fast post-fabrication tuning process based on space mapping technique is proposed for tuning 3D-printed air-filled waveguide filters with tolerance and insertion loss. Surrogate modeling and parameter extraction process for post-fabricated filter are discussed. The tuning algorithm is presented in detail.To validate the proposed method, it is applied to a metallic air filled X-band iris tunable waveguide filter fabricated using selective laser sintering (SLS) technology.The target filter is fabricated in an irregular process in which it is split into three sections with extra flanges for connection after fabrication.This process significantly reduces the time and cost to fabricate a 5 inch large filter for 3D printing. But it also results in extra alignment tolerance and return loss. By applying the tuning algorithm, we are able to significantly reduce the return loss in just one iteration and define the tuning range of the filter.

The physically derived micro-modeling circuit is an order-reduced RLC circuit of a PEEC circuit for a large-scale packaging problem. Unlike traditional model order reduction (MOR) methods, this method can reduce the order of the circuit by an order of magnitude without any matrix inversions and decompositions. As its dominant computation is outer products of a vector by itself, the scheme is highly suitable for parallel computation. This paper proposes an effective collaborative acceleration strategy for deriving a micro-modeling circuit using a GPU module. The strategy combines an efficient parallel computation of a vector outer products using GPU and an I/O optimization for data transfer between CPU and GPU. A numerical example shows that the proposed acceleration for deriving the micro-modeling circuit is achieved significantly. It is demonstrated that the micro-modeling scheme is highly suitable for a large-scale interconnection and packaging problem.

This paper presents a novel 3D inductor (solenoid) fabricated on a 50-μm thick AAO membrane using nanowire-vias. Several inductors were fabricated in this simple and low-cost technology with nanowires. They were measured up to 110 GHz and compared to the state-of-the-art results presented in the literature in different technologies: CMOS, glass, LCP and MEMS. The simulations are in good agreement with measurement, predicting the great potential of these inductors. The first 3D inductors using nanowire-vias presented inductances from 0.5 nH to 1.7 nH having a small area of 0.03 mm² to 0.08 mm².

On-chip copper (Cu) based S-RuM inductors are demonstrated for the first time. Compared to the gold (Au) based S-RuM inductor, device structures and fabrication processes are re-designed to realize CMOS compatibility by switching conduction metal to Cu and overcoming related processing challenges. Performance enhancements include ~44% reduction of conduc-tion layer resistivity, and a clear path to 100% fabrication yield are achieved. RF measurement shows as high as ~ 61nH/mm2 inductance density with just a 2-turn structure for these air-core S-RuM inductors. The achieved inductance is in the range from 0.3nH - 1nH. The best self-resonant-frequency (SRF) and quality factor (Q factor) of 1nH device is ~21GHz and ~2.3@5GHz, respectively. Much better performance can be readily obtained by rolling up more turns and integrating soft magnetic material film and core. Results show that Cu S-RuM inductor is very promising to re-place on-chip planar inductor with better performance as new industry standard.

In this paper we report a compact, zero-biased Graphene-based power detector circuit based on our in-house metal-insulator-Graphene (M I G) diode fabricated on glass substrate. The designed circuit is optimized for the frequency band 40 − 75 GHz. Measurements show dynamic range of more than 50 dB with down to −50 dBm sensitivity. The measured responsivity for the fabricated circuit on glass is 160 V/W at 5.5 GHz and it reaches 15 V/W at 60 GHz without calibration for substrate losses. Measurement results together with the introduced CVD Graphene process promote the proposed circuit and device for repeatable, statistically stable millimeter-wave and sub-millimeter wave circuits applications.

In this paper, the development of graphene research of the past decade is briefly reviewed, and its potential application of microstrip devices is discussed. Besides, some relational theories are mentioned and the employed fabrication processes are introduced as well. To verify the concept, an optically transparent (ultraviolet, visible light, infrared) graphene microstrip bandpass filter operates at the center frequency of 5.8 GHz is designed and fabricated. The center frequency and bandwidth can be freely adjusted. The measured frequency responses exhibit the same tendencies as the simulated results, which prove the effectiveness of this design.

The design, fabrication and experimental validation of a novel near-field scanning millimeter-wave microscope (NSMM) built inside a scanning electron microscope (SEM) is presented. The instrument developed can perform hybrid char-acterizations by providing simultaneously atomic force, complex microwave impedance and electron microscopy images of a sam-ple with nanometer spatial resolution. By combining the meas-ured data, the system offers unprecedentable capabilities for tackling the issue between spatial resolution and high frequency quantitative measurement.

We introduce an accurate analysis and characterization of the plasmonic onset and propagation in meso- and nano-structured metals. This method developes into three steps, i) the Kretschmann configuration technique, ii) the Fresnel's coefficients approach and iii) a full-wave multi-scale numerical simulation. The method is applied and tested to examples from the literature, dealing with noble metals as silver and gold. The theoretical results are in excellent agreement with the experimetal ones, thus confirming the versatility and efficiency of the method, that can be applied also to 2D materials like graphene. The final aim is the design and simulation of plasmonic nanodevices in both the optical (noble metals) and the THz range (2D-materials like graphene).

As opposed to traditional approaches for extracting small-signal equivalent circuits of active devices, the use of extensive electro-magnetic (EM) simulations has been more recently demonstrated by several Authors. This contribution outlines the extraction of two kinds of EM-based models for a common-source and a common-gate device in a 250 nm GaN HEMT technology, namely a compact model (representing the intrinsic as a threeterminal network) and a multi-finger one (splitting the intrinsic region into elementary units). The latter representation, which is unique of the EM-based approach, is shown to accurately predict the stability properties of the actual common-gate device, whereas the compact model, notwithstanding the apparent similarity as to S-parameter modeling, misses the observed instability.

The nonlinear drain-source capacitance(Cds) of source field plated power RF GaN device has been modeled by an artificial neural network(ANN) for easy integration with a compact model. This hybrid modeling approach can be suitable for a quick, technology independent solution to a complex problem. In this study it is shown that the proposed hybrid model based on a modified EEHEMT model demonstrates improved large signal accuracy over wide drain bias ranging from 28V to 65V when compared to the fixed Cds used in the stand-alone compact model.

We propose a numerically efficient technique for the mixed-mode physics-based variability analysis of microwave circuits undergoing concurrent variations in the active device and in the external passive network, allowing for a direct link between the spread of nonlinear circuit performances and the variability of technological parameters. The new technique has been validated against repeated physical load-pull simulations of a class AB power amplifier with random variations of the active device gate length and of the external load, showing an excellent precision and a massive reduction of simulation time.

A simple expression for the conductance-voltage characteristics of resonant tunneling diodes (RTD) is presented, which takes the asymmetry of the measured characteristics into account. It allows for a simple and accurate analysis of RTD based oscillators to optimize them. The dynamic capacitance of a RTD oscillator is calculated in order to describe its oscillation frequency. The measured oscillation power and frequency accurately can be described using the presented model and analysis without the need of a circuit simulator.

Hybrid Substrate Integrated Non Radiative Dielectric Slab Waveguides are proposed as a new guiding structure suitable for mm-wave components. The proposed structure is a combination of two well-known guiding structures, each of which has its wide variety of applications but in different regimes of operation. The combination of the two guiding mechanisms in one physical structure gives unique characteristics to the resulting hybrid waveguide. A systematic analytical way is presented in this paper to characterize the new waveguide in terms of its dispersion relation, modes of operation, field solution, bandwidth of single mode operation, and power handling capability. Some possible applications and design recipes are discussed.

A new resonance phenomenon is discussed and demonstrated by experiment in a dual-polarization cavity. The resonance is formed by waves bouncing between two anisotropic metasur-faces placed at the cavity ends. The simple metasurfaces are designed to preserve the handedness of circularly polarized waves upon reflection. The standing waves resulting from such reflections do not have nodes and antinodes. A theoretical solution to the resonance condition is discussed, both for plane-waves and equivalent guided waves. The concept is then experimentally applied to dual-mode guided waves, demonstrating a very short cavity at X-band. This brings new possibilities for resonator design and can potentially be used in microwaves, mm-waves and beyond.

This study deals with the development of a unified model for the design of microwave absorbers. This tool unifies the modeling of electromagnetic properties of composite materials and the modeling of microwave absorbers made of these composites. It makes it possible to calculate thickness and formulation of the composite that allows minimizing reflectivity. It takes into account shape effects linked to microstructure and is valid for dielectric and magnetic materials. The design of a bilayer screen made of polymers loaded with ferromagnetic particles is given as an example. This tool can be used to help radar absorbing materials manufacturers in the formulation of materials dedicated to a specific band of frequencies.

A novel anti-reflection (AR) theory based on an anisotropic material is developed in this paper. The anisotropic AR layer can be designed to match to a high-index substrate at any incident angle, including extreme ones. The AR coating is realized by metamaterial structures that can be fabricated on standard PCBs. Perfect matching is achieved at 88 degrees in simulation and experimental results are presented for 60 degrees.