Active Microwave Devices Research Articles

Equivalent Circuits Application of Pin-Diodes and MEMS-Keys in Electrodynamic Modeling Problems

This article studies the possibility of using circuit formats to describe radio components in electrodynamic modeling problems. The study was carried out on the example of a controlled metamaterial in the form of an electromagnetic crystal with SPICE-models of equivalent circuits of pin-diodes and MEMS-keys. Also, the possibility of using Touchstone files as an alternative format for describing radio-electronic components was considered. The obtained results are illustrated by scatter matrix plots, as well as equivalent circuits and SPICE code. Obtained results can be used for the design of structures that combine active nonlinear radio components and microwave devices.

Time-Efficient Adaptive Procedure for Identification of Multitone X-Parameters

A novel measurement procedure for the time-efficient identification of multitone <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -parameters of active microwave devices and circuits is introduced. Over a given bandwidth, the procedure allows for an adaptive selection of key spectral components necessary for determining the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -parameters characteristics with a minimum measurement effort. The sequential selection is based on the divide-and-conquer algorithm. It results in a huge reduction of the measurement time in comparison to the situation when model coefficients at all spectral components are identified. To validate the procedure, an off-the-shelf broadband power amplifier (PA) was characterized under wideband large-signal excitation conditions. Moreover, small-signal terms at all relevant frequencies were collected as a reference and compared with the results provided by a time-efficient adaptive procedure (TEAP). The proposed method resulted in twenty times reduction in the number of samples required to characterize the PA. As an application example, the small-signal coefficients identified with the TEAP are used to correct characterization results for the measurement instrument’s output mismatch. The mismatch-corrected output signal of the PA under test was represented accurately with the error-vector-magnitude of only 0.132%.

A Lightweight Position-Enhanced Anchor-Free Algorithm for SAR Ship Detection

As an active microwave device, synthetic aperture radar (SAR) uses the backscatter of objects for imaging. SAR image ship targets are characterized by unclear contour information, a complex background and strong scattering. Existing deep learning detection algorithms derived from anchor-based methods mostly rely on expert experience to set a series of hyperparameters, and it is difficult to characterize the unique characteristics of SAR image ship targets, which greatly limits detection accuracy and speed. Therefore, this paper proposes a new lightweight position-enhanced anchor-free SAR ship detection algorithm called LPEDet. First, to resolve unclear SAR target contours and multiscale performance problems, we used YOLOX as the benchmark framework and redesigned the lightweight multiscale backbone, called NLCNet, which balances detection speed and accuracy. Second, for the strong scattering characteristics of the SAR target, we designed a new position-enhanced attention strategy, which suppresses background clutter by adding position information to the channel attention that highlights the target information to more accurately identify and locate the target. The experimental results for two large-scale SAR target detection datasets, SSDD and HRSID, show that our method achieves a higher detection accuracy and a faster detection speed than state-of-the-art SAR target detection methods.

Design and Test of Innovative Three-Couplers-Based Bandpass Negative Group Delay Active Circuit

An innovative design method of bandpass (BP) negative group delay (NGD) active circuit is developed. The BP NGD topology consists originally of octopole and hexapole coupled line (CL) couplers. The NGD active circuit is validated by a prototype implemented in hybrid technology. The measured results are in good agreement with simulations. The CL-based passive circuit generates BP NGD performance with simulated and measured results showing NGD level of approximately -12 ns having 1.97 GHz center frequency with -11 dB transmission coefficient and -16 dB reflection coefficient. To compensate the loss, active circuit was fabricated by cascading the passive circuit with a microwave amplifier. Subsequently, the previous BP NGD performance is achieved with 0 dB gain. Moreover, a notable active microwave device characterization is performed with the NGD prototype via nonlinear measurements. It was found that the tested NGD prototype operates with 10-dB noise figure, 21 dBm P1dB compression, 29 dBm and 41 dBm OIP3.

EXCITATION OF MAGNETOPLASMA OSCILLATIONS IN SEMICONDUCTOR STRUCTURES BY FLUXES OF CHARGED PARTICLES

The subject of the papers is the processes of analysis and physical model of excitation (amplification) of magnetoplasma oscillations (helicons) by fluxes of charged particles (electrons) in the presence of a constant magnetic field. This model is based on the Cherenkov mechanism for converting kinetic energy of particles into the energy of natural electromagnetic oscillations of solid-state (semiconductor) structures under resonance conditions when the particle velocities coincide with phase velocities of oscillations. The aim here is to justify the formulation of theoretical studies basing on the proposed physical model of generation (amplification) of electromagnetic oscillations (emergence of oscillation instabilities, i.e., exponential growth of their amplitude). We define parameters intervals for the external magnetic field, particle fluxes and types of semiconductor structures which this physical model is applied to. We perform theoretical study of the influence charged particle fluxes have on waveguide characteristics of semiconductor structures. The study justifies the possibility of generation and amplification of magnetoplasma oscillations in the submillimeter range. Our objectives are theoretical studies of the interaction of moving charges with electromagnetic oscillations of a semiconductor structure under conditions of Cherenkov radiation. The methods used are the method of successive approximations for solving the dispersion equations for a system of charged particle flux - semiconductor structure within the framework of hydrodynamic approach. The following results are obtained: Theoretical studies of the functioning of semiconductor components of electrical radio equipment in the presence of charged particle fluxes have been carried out. It is shown that the effect of the particle flux is characterized by the emergence of oscillation instabilities in the semiconductor structure. We have determined one of the mechanisms for the excitation of magnetoplasma oscillations based on the interaction of moving charges with the intrinsic fields of the structures that constitute a semiconductor unit. Such equipment failures occur under conditions of Cherenkov radiation. We have shown that this interaction leads to appearance of a mode of oscillation generation. The results of a comparative analysis of the data obtained in this work make it possible to use the proposed physical model to determine the criteria for the occurrence and development of instabilities of magnetoplasma oscillations. Conclusions. The results obtained in this work can be used in the development of active microwave range devices (amplifiers, generators and transducers of electromagnetic oscillations of the millimeter and submillimeter bands). The comparative analysis of quantitative estimates of the growth rates of oscillation instabilities, depending on the spatial configuration of the acting field (when induced current is parallel to the structure boundary), carried out in this work, provides a solution to the problem of optimizing the operating characteristics of active microwave devices.

EXTERNAL PARAMETERS OF THE CONNECTION OF A RECTANGULAR WAVEGUIDE PARTIALLY FILLED OF LINEAR DIELECTRIC WITH A RECTANGULAR WAVEGUIDE PARTIALLY FILLED OF NONLINEAR DIELECTRIC

. In the article, the external parameters of the connection of a rectangular waveguide partially filled of linear dielectric with a rectangular waveguide partially filled of a nonlinear dielectric are determined. Knowledge of the external parameters of such a connection ensures the design of devices with open nonlinear elements. Promising microwave paths of radio engineering systems based on rectangular waveguides partially filled of dielectric include a wide variety of active and passive microwave devices. The plane-transverse junction of these waveguides is considered for various geometric dimensions of dielectric plates and their relative permittivity. Such a junction is characterized by reactive conductivity, which is determined through the sum of the reactive conductivities of local fields. The transverse electric field at the junction is represented through the eigenvector function of the geometric surface, which coincides with the cross section of the waveguides. The scattering matrix of the plane-transverse junction is determined through the conductivity of the sections of the two waveguides and the conductivity of the plane-transverse junction. The dependences of the traveling wave coefficient and the modulus of the reflection coefficient on the geometric dimensions of the dielectric plate are plotted taking into account the local fields generated at the plane transverse junction. At the junction of two waveguides, not only changed the geometric dimensions of the dielectric plates along the wide and narrow walls of the waveguide, but also their relative permittivity. In one case, two higher types of waves were taken into account: quasi - H30 and quasi - H12, in the other case - four higher types of waves: quasi - H30, quasi - H12, quasi - E12, quasi - H50. Calculations show that an increase in the number of higher types of waves has practically no effect on the accuracy of calculations. The results obtained indicate the rapid internal convergence of the obtained solutions and the correct choice of the transverse electric eigenvector function of rectangular waveguides partially filled of dielectric as approximate the field on the junction of two waveguides.

Bandgap Control of Two-Dimensional Coaxial Bragg Structures With Helically Corrugated Conductors

The untunable bandgap is a difficult problem for Bragg structures constructed from corrugated metallic waveguides, and becomes a major barrier for applications. Based on the coupled-mode theory, this paper presents the principle as well as a corresponding theoretical model of bandgap control of two-dimensional coaxial Bragg structures under the condition of a fixed ripple shape. It is shown that such control can be achieved by varying the angular deviation between the outer and inner corrugations, which can be done by rotating one of the conductors relative to the other. The effects of the proposed method on transmission bandgap control of two example structures were investigated by theoretical analysis and electromagnetic simulation. The results confirmed the validity of the proposal, and showed that such a control method can be used to manipulate the number and location of the working bands under multiple bandgap operation. These peculiarities provide potential applications of two-dimensional coaxial Bragg structures in constructing tunable passive and active high-power microwave devices.

An Experimental Study of a Regenerative Secondary Source of Microwave Energy

To create systems for remote metering of electric energy consumption, it is necessary to design new types of active microwave devices based on secondary signal sources that implement control of the electromagnetic field intensity. Current advances in the theory of electronic wave circuits let us to simulate correctly nonlinear and wave processes in circuits. At the same time, to use any components it is necessary to estimate the potential for technical implementation of the required electrical and geometric parameters, combining and embedding possibilities for proposed design solutions in the modern electronic equipment. Therefore, such an engineering approach requires experimental verification for the original calculations obtained analytically. The article presents the results for experimental modeling of a secondary microwave signal source, which allows to study the phenomenon of electrical energy regeneration by a negatron, a bipolar element with negative resistance. The experiments was carried out on the basis of the P2-67 meter, which allows to identify clearly the type of amplitude-frequency characteristics of the verification model in the three-centimeter wave range. The obtained information on its operating in the reflective and pass-through mode substantiate the choice of the active element and the microstrip realization for the resonant tuning system, which simultaneously functioning as a supply circuit. The possibility for constructive synthesis of a test model using a serial 2A706 avalanche-span diode is shown. Such a secondary source provides effective and controlled variation of the intensity of the re-emitted signal by recuperating and amplifying microwave power in practice.

Neural network electrothermal modeling approach for microwave active devices

This article presents an artificial neural network (ANN) approaches for small- and large-signal modeling of active devices. The small-signal characteristics were modeled by S-parameters based feedforward NN models. The models have been implemented to simulate the bias, frequency and temperature dependence of measured S-parameters. Feedback NN based large-signal model was developed and implemented to simulate the drain current and its inherent thermal effect due to self-heating and ambient temperature. Both small- and large-signal models have been validated by measurements for 100-μm and 1-mm GaN high electron mobility transistors and very good agreement was obtained.

Твердотельные СВЧ-модули для радиотехнической аппаратуры и систем миллиметрового диапазона длин волн

The paper presents scientific, technological and production potential of Research Institute «Orion» in the field of creation of wide range of high performance active and passive solid-state microwave devices, modules and components as well as multifunctional devices on their basis. These products taken as a whole form a component base for promising equipment and systems working in the frequency range from 1.0 to 200 GHz.

JOINT OFFSHORE WIND FIELD MONITORING WITH SPACEBORNE SAR AND PLATFORM-BASED DOPPLER LIDAR MEASUREMENTS

Abstract. The increasing demand for renewable energy resources has promoted the construction of offshore wind farms e.g. in the North Sea. While the wind farm layout consists of an array of large turbines, the interrelation of wind turbine wakes with the remaining array is of substantial interest. The downstream spatial evolution of turbulent wind turbine wakes is very complex and depends on manifold parameters such as wind speed, wind direction and ambient atmospheric stability conditions. To complement and validate existing numerical models, corresponding observations are needed. While in-situ measurements with e.g. anemometers provide a time-series at the given location, the merits of ground-based and space- or airborne remote sensing techniques are indisputable in terms of spatial coverage. Active microwave devices, such as Scatterometer and Synthetic Aperture Radar (SAR), have proven their capabilities of providing sea surface wind measurements and particularly SAR images reveal wind variations at a high spatial resolution while retaining the large coverage area. Platform-based Doppler LiDAR can resolve wind fields with a high spatial coverage and repetition rates of seconds to minutes. In order to study the capabilities of both methods for the investigation of small scale wind field structures, we present a direct comparison of observations obtained by high resolution TerraSAR-X (TS-X) X-band SAR data and platform-based LiDAR devices at the North Sea wind farm alpha ventus. We furthermore compare the results with meteorological data from the COSMO-DE model run by the German Weather Service DWD. Our study indicates that the overall agreement between SAR and LiDAR wind fields is good and that under appropriate conditions small scale wind field variations compare significantly well.

Compact Behavioral Models of Nonlinear Active Devices Using Response Surface Methodology

This paper presents the response surface methodology in modeling of nonlinear microwave devices. First, different combinations of sampling techniques and types of radial basis functions are evaluated in simulations of the drain current of a 0.15- μm GaAs HEMT transistor described by the Chalmers model. It allows to determine the best settings of the response surface methodology for the modeling of active microwave devices. It is shown that the best sampling strategy is a combination of space-exploration (Voronoi), problem-exploitation (LOLA), and model-error-driven sample rankers. From the various radial basis function models, the fastest convergence is achieved with exponential functions. This knowledge is then used in behavioral modeling of a low-power amplifier AG303 measured in the load-pull setup. It is shown that the response surface methodology outperforms commonly used factorial design of experiments. Moreover, it gives accurate models within just a few tens of samples. However, attention has to be paid at the noisy regions, which might be oversampled by the sampling techniques.

A Microwave Modeling Oxymoron?: Low-Frequency Measurements for Microwave Device Modeling

For a number of decades, the modeling of microwave transistors relied on specific well-known characterization methods. Those methods include S-parameters measurement through vector network analyzers (VNAs) ranging from the lower end of the RF spectrum to the millimeter-wave (mm-wave) region and load pull measurements of transistors used for the design of power amplifiers (PAs). Later, the availability of more powerful computer-aided design (CAD) software enabled the need for models of active microwave devices, thus driving a huge amount of research activity on microwave transistor modeling. Simultaneously, new transistor technologies were invented, combining working concepts such as heterojunction bipolar transistors (HBTs), metal semiconductor field effect transistors (MESFETs) or high electron mobility transistors (HEMTs) and new materials such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), and silicon germanium (SiGe), to cite only the main ones.

Considerations on the $ {{ 4 {{NT}}_{\rm o} }/{ {T}_{\rm m}}}$ Ratio and the Noise Correlation Matrix of Active and Passive Two-Port Networks

The constraint on the Wiatr–Pospieszalski (WP) parameter <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}= {{ 4 {NT}_{\rm o} }/{ {T}_{\rm m}}}\leqslant 2$</tex></formula> , where <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$ {\hbox{N}}$</tex></formula> is the Lange invariant and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ {T}_{\rm m}$</tex></formula> the minimum equivalent noise temperature and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ {T}_{\rm o}={\hbox{290}}~ \left ( {\hbox{K}} \right )$</tex> </formula> , has been suggested as a validation tool for the characterization of active microwave devices, despite its acknowledged limitations. This paper provides a solid theoretical background on <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$ \Theta _{\rm W\!P}$</tex></formula> that is used to investigate noisy linear two-port networks. In particular, parallel feedback is discussed thoroughly in order to understand its effect on the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}$</tex></formula> parameter and determine the conditions for which <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}$</tex></formula> is larger or smaller than 2. A suitable expression that explains the conditions for <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$ \Theta _{\rm W\!P}$</tex></formula> of on-chip devices to be less than 2 is obtained. The theoretical results are supported by a scalable GaN device model extracted from measurements providing further insight into the noise performance of microwave devices. Finally, the investigation is applied to passive two-port networks to highlight the singular properties of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}=2$</tex> </formula> . The broad result of this paper's investigation is that the constraint <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}\leqslant 2$</tex> </formula> is not a property of the noise parameter matrix as the constraint <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1\leqslant \Theta _{\rm W\!P} $</tex> </formula> is; yet, the threshold <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \Theta _{\rm W\!P}=2$</tex></formula> is demonstrated to have unique features for both active and passive two-port networks. Alternative and original demonstrations of the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1\leqslant \Theta _{\rm W\!P} $</tex></formula> constraint are also obtained as a byproduct of the investigation.

Inkjet‐printed antennas, sensors and circuits on paper substrate

Inkjet-printing is a very promising technology for the development of microwave circuits and components. Inkjet-printing technology of conductive silver nanoparticles on an organic flexible paper substrate is introduced in this study. The paper substrate is characterised using the T-resonator method. A variety of microwave passive and active devices, as well as complete circuits inkjet-printed on paper substrates are introduced. This work includes inkjet-printed artificial magnetic conductor structures, a substrate integrated waveguide, solar-powered beacon oscillator for wireless power transfer and localisation, energy harvesting circuits and nanocarbon-based gas-sensing materials such as carbon nanotubes and graphene. This study presents an overview of recent advances of inkjet-printed electronics on paper substrate.

Microwave signal conditioning through non‐reciprocal phase shifting

Two non-reciprocal microwave signal conditioning circuits, a non-reciprocal phase shifter and a quasi-circulator, are proposed as based on the use of active microwave devices. Analytical expressions are derived to demonstrate the principles of operation and prototypes are presented both in hybrid and monolithic form. The hybrid structures operate in the L-band, whereas the monolithic ones are designed for X-band operation, and demonstrate the compactness and performance of the proposed topologies.

Straightforward modeling of dynamic I-V characteristics for microwave FETs

This work presents a straightforward approach aimed at modeling the dynamic I–V characteristics of microwave active solid-state devices. The drain-source current generator represents the most significant source of nonlinearity in a transistor and, therefore, its correct modeling is fundamental to predict accurately the current and voltage waveforms under large-signal operation. The proposed approach relies on using a small set of low-frequency time-domain waveform measurements combined with numerical optimization-based estimation of the nonlinear model parameters. The procedure is applied to a gallium nitride HEMT and silicon FinFET. The effectiveness of the modeling procedure in terms of prediction accuracy and generalization capability is demonstrated by validation of the extracted models under operating conditions different than the ones used for the parameters estimation. Good agreement between measurements and model simulations is achieved for both technologies and in both low- and high-frequency range. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:109–116, 2014.

Application of data mining methods to efficient microwave active device modeling

In this work, the signal and noise behaviors of a microwave transistor within its operation domain (voltage drain to source–VDS, current of drain to source—IDS, frequency—f) are modeled by data mining techniques (DMT) without using any information on the microwave circuit theory. The device is modeled by a black box whose small signal (S) and noise parameters are evaluated through data mining techniques, based on the fitting of both of these parameters for multiple bias and configuration. It has been shown that DMT have a high potential of faithful and efficient device modeling. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.

Modeling the Behavior of HTS Terahertz RSQUIDs

In previous work we looked in detail at simulations of our HTS Resistive DC SQUIDs (RSQUIDs) using a lumped-component model and neglecting step-edge junction capacitance. These can now be made with junctions that have a high product of critical current and normal resistance ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</sub> ) and so the Josephson frequency can be above 1 THz. This calls for a more refined model of the device, which we will present here. The RSQUID series resistor is represented as a distributed combination of resistance and inductance, rather than simply a resistor in series with its self inductance. We now include junction capacitance, as the Stewart-McCumber parameter can be close to unity. We treat the RSQUID loop as a co-planar stripline, rather than as an inductor. We report a range of simulations with these enhancements to the model and comment briefly on the results in relation to potential applications of RSQUIDs as active microwave devices.

Smart Modeling of Microwave Devices

Modeling and computer-aided design (CAD) techniques are essential for microwave design, especially with the drive towards first-pass design success. We have described neural networks for microwave modeling and design. Neural networks are suitable when modeling a required relationship for which analytical formulas are hard to derive, or for which the computational effort is too high. This relationship can be either of the IO relationship of the overall model (straight neural network model), the output-input relationship (inverse model), a relationship between existing model and desired data (neuro-SM), or relationship of a subpart of the overall model (knowledge based neural network). Neural networks are fast to evaluate, and the neural network formulas are easy to implement into microwave CAD. The simplicity of adding input neurons or hidden neurons makes neural network flexible in handling functions of different dimensions and of different degree of nonlinearity. We have also demonstrated that neural networks are helpful in developing parametric or scalable models for passive and active microwave devices.