Microwave Electronics Research Articles

Analysis of noise characteristics of a diode generator in a multi-circuit system

In modern microwave electronics, it is extremely important to evaluate the possibility of efficient generation of highly stable oscillation modes and the creation of low-noise generators with a millimeter wavelength range. The purpose of the research was to determine the type of wave for the most effective modes of oscillation and to ensure the operation of various modes in the mode of mutual synchronization, which becomes possible because the real design of generators can include a number of reactive elements that form a number of resonant frequencies in the microwave range. This paper shows how it is possible to provide conditions for generation at a particular frequency and simultaneously obtain high stability of vibrations. The main research methods were: analysis and generalization of literature data and results of our own research on the peculiarities of oscillation generation in a multi-circuit system of a Gann diode generator and conditions under which high frequency stability is established; experimental studies using microwave spectrum analyzers, microwave devices. In this paper, the possible generation frequencies are calculated, the operation modes of the diode generator are studied, and their phase noise is experimentally measured. It is shown that when the generation frequency approaches the cut-off frequency of the waveguide with the help of structural elements or by changing the supply voltage, a mode of mutual synchronization of vibrations at high harmonics occurs using the H102 wave type in a very narrow range of frequency (phase) noise. A generator with a multicircuit resonant system was experimentally studied and a small amount of phase noise was obtained for both types of H101 and H102 waves. At the same time, the best parameters and noise characteristics occurred at the lowest types of vibration types. These results have an experimental novelty, which allows us to hope for the development of constructive solutions that provide the creation of highly stable low-noise generators of millimeter wavelength range with the minimum mass dimensional parameters.

Ultrafast THz-driven electron emission from metal metasurfaces

Field-driven emission of electrons from metals is a technology that has had a large impact on science and society over the past century, for instance, in early and contemporary vacuum tube electronics, cathode ray displays, and high-power microwave and sub-millimeter electronics. In this Perspective article, we discuss the role of field-driven electron emission in the broader context of tunneling phenomena, and we discuss some aspects of the physics behind field emission. We focus on the use of ultrafast single-cycle transients of electromagnetic radiation in the terahertz (THz) frequency range to drive the electron emission process. With electric fields of such short duration, it becomes possible to generate electron bursts of sub-picosecond duration controllable on the sub-cycle time scale due to the large nonlinearity of the emission process. We review the recent literature on THz-driven field emission and then finally present selected experiments from our own laboratories to emphasize aspects such as design of the emitter structure with respect to optimal field enhancement properties, measurement of the electron bunch duration, visualization of the spatial emission pattern of emitted electrons, and material damage caused by the electrons.

Comprehensive study on structural, electrical, magnetic and photocatalytic degradation properties of Al3+ ions substituted nickel ferrites nanoparticles

A series of Al3+ substituted NiAlxFe2-xO4 (0.0 = x ≤ 0.5) nanoparticles was synthesized using the chemical co-precipitation route. The effect of Al3+ ions doping was investigated in terms of structural, degradation, magnetic and electrical properties of the nanoparticles (NPs). The XRD patterns confirmed the formation of the spinel cubic phase. FT-IR spectra revealedtwo consistent absorption bands indicating the intrinsic stretching vibrations of O2- Fe3+ around 591-615 cm−1 and 416-428 cm−1 bond lengths for tetrahedral and octahedral sites respectively. The magnetic properties decrease as the concentration of Al3+ increases. The decrease of magnetic parameters can be explained by the difference between magnetic moments of Al3+ and Fe3+ cations. Maxwell-Wagner model of space charge polarization was utilized to explain the dielectric properties with frequency. The increasing dielectric losses indicated the suitability of synthesized NPs for microwave absorption, telecommunication, electronics and other high frequency applications. The dependence of dielectric properties on grains and grain boundaries was further investigated via impedance spectroscopy and complex electric modulus. The study of photo-degradation efficiency of NPs was performed using organic methylene blue dye. The results showed satisfactory degradation with maximum degradation efficiency of 84.45% for NPs with composition NiAl0·5Fe1·5O4.

Optical sensitivity of HEMT-based devices and low-noise amplifiers

ABSTRACT The aim of this paper is to provide a complete and clear overview of the distinguishing dc and microwave features of HEMT performance under illumination. Devices based on different materials and technologies have been employed, thus making clear that the relevant findings can be considered of general validity. The analysis has been carried out in terms of dc, scattering and noise parameters, and supported with extensive measurements and in-depth modelling. Finally, the performance of X-band low-noise amplifiers with HEMTs exposed to laser radiation has been investigated. This study targets to contribute in the development of optically controlled transistors to perform various functions in microwave electronics circuits.

Strain-induced room-temperature ferroelectricity in SrTiO3 membranes

Advances in complex oxide heteroepitaxy have highlighted the enormous potential of utilizing strain engineering via lattice mismatch to control ferroelectricity in thin-film heterostructures. This approach, however, lacks the ability to produce large and continuously variable strain states, thus limiting the potential for designing and tuning the desired properties of ferroelectric films. Here, we observe and explore dynamic strain-induced ferroelectricity in SrTiO3 by laminating freestanding oxide films onto a stretchable polymer substrate. Using a combination of scanning probe microscopy, optical second harmonic generation measurements, and atomistic modeling, we demonstrate robust room-temperature ferroelectricity in SrTiO3 with 2.0% uniaxial tensile strain, corroborated by the notable features of 180° ferroelectric domains and an extrapolated transition temperature of 400 K. Our work reveals the enormous potential of employing oxide membranes to create and enhance ferroelectricity in environmentally benign lead-free oxides, which hold great promise for applications ranging from non-volatile memories and microwave electronics.

Heterogeneously integrated flexible microwave amplifiers on a cellulose nanofibril substrate

Low-cost flexible microwave circuits with compact size and light weight are highly desirable for flexible wireless communication and other miniaturized microwave systems. However, the prevalent studies on flexible microwave electronics have only focused on individual flexible microwave elements such as transistors, inductors, capacitors, and transmission lines. Thinning down supporting substrate of rigid chip-based monolithic microwave integrated circuits has been the only approach toward flexible microwave integrated circuits. Here, we report a flexible microwave integrated circuit strategy integrating membrane AlGaN/GaN high electron mobility transistor with passive impedance matching networks on cellulose nanofibril paper. The strategy enables a heterogeneously integrated and, to our knowledge, the first flexible microwave amplifier that can output 10 mW power beyond 5 GHz and can also be easily disposed of due to the use of cellulose nanofibril paper as the circuit substrate. The demonstration represents a critical step forward in realizing flexible wireless communication devices.

Frequency Tuning of the Elementary Base of Microwave Electronics Using Structured Htsc Films

Abstract—A study of the current–voltage characteristics of structured high-temperature superconducting (HTSC) films based on YBa2Cu3O7 – x–YBa2Cu3O7 – x showed that the critical current of the film structure with an area of 10.0 × 10.0 mm2 can be reduced from 10 A up to 100 mA. By the example of an HTSC resonator, it is shown that in the millimeter wavelength range, with a resonance response width of 2∆f = 20–30 MHz at a level of 0.5 of its amplitude, a structured film used as an “grounded” plane permits tuning of the resonator in a band of at least 300 MHz.

Эффект трансформации электрического поля в анизотропных диэлектрических средах

The authors consider the aspects of the electric field distribution in an anisotropic medium and establish how its longitudinal and transverse components depend on the geometric factors. A rectangular plate of dimensions a×b×c is studied, its selected crystallographic axes located in the plane of the side face (a×b), while one of the axes is oriented at a certain angle α to the edge a. It is shown that applying a certain potential difference to the upper and lower faces electrically polarizes the volume of the plate and causes the appearance of the longitudinal and transverse components of the internal electric field. The authors investigate the possibility of transforming the magnitude of the electric field and methods for its optimization. The transformation coefficient of such a device is determined by the anisotropy of the dielectric permeability of the plate material and its shape coefficient k = a/b. The paper considers one of the design options for an anisotropic dielectric transformer and proposes its equivalent electrical circuit. Structural elements based on anisotropic dielectric transformers may be widely used both in power supplies of various electronic devices and for coordination of radar transceiver systems with antenna arrays of centimeter, millimeter and submillimeter wavelength ranges. The possibility of simultaneous transformation of constant and alternating electric fields allows them to be used in devices of simultaneous comparison, enabling to determine the current values of voltage, as well as the power of electromagnetic radiation in a wide range of wavelengths. The vortex nature of the electric field in the plate’s volume caused by the coefficient anisotropy of the dielectric permeability also creates the preconditions for the emergence of new principles for generating high-power electromagnetic radiation in a wide spectral range. The generation frequency of such devices is determined by the geometric dimensions of the anisotropic plate. The use of the described transformation effect will significantly expand the possibilities of practical application of the considered electrostatic phenomena, which will lead to the emergence of a new generation of devices for microwave technology, electronics and electric power.

Трансформация электрического тока анизотропными электропроводными средами

The authors consider the aspects of electric current distribution in electrically conductive anisotropic medium and establish how geometrical factors affect its longitudinal and transverse components. In the case of an a×b×с rectangular plate, its selected crystallographic axes are located on the plane of the side face a×b, whereas one of these axes is oriented at an angle α to the edge a. Applying a certain potential difference to the upper and lower end faces of the plate causes the appearance of longitudinal and transverse components of the internal electric current. The paper demonstrates the possibility of transforming the magnitude of the electric current and a way to optimize this magnitude. The transformation coefficient of such a device is determined by the anisotropy of the electrical conductivity of the plate and the coefficient of its shape k = a/b. The authors consider a few versions of anisotropic dielectric transformer design and offer their equivalent electric circuits. Another suggested transformer design is spiral in shape, compact and is characterized by high transformation coefficient value n. For example, at external radius r1 = 12,5 mm, internal radius r2 = 2 mm, height b = 2 mm and plate thickness c = 2,0 mm, its transformation coefficient n = 103. The information is given on existing monocrystalline and artificial anisotropic materials that can be used for the proposed device. High-temperature superconducting materials characterized by a high value of residual resistance anisotropy hold special promise in this case. Using the described transformation effect will significantly expand the possibilities of practical application of the considered electroohmic phenomenon. This will lead to the emergence of a new generation of devices for microwave technology, electronics and power engineering.

Pulsed power technology based on semiconductor opening switches: A review.

This paper presents a systematized review of the research on the production of nanosecond high-power pulses using solid-state generators based on an inductive energy store and a semiconductor opening switch that have been performed in the past 25 years. This research has been underway since 1992-1993 when the nanosecond cutoff of ultrahigh-density currents in semiconductor diodes was discovered and named the SOS (Semiconductor Opening Switch) effect. The discovery of the SOS effect provided a breakthrough in the development of semiconductor generators, as their most important characteristics, such as pulse power and output voltage, were increased tens and hundreds of times compared with previously known semiconductor generators. In particular, in the nanosecond semiconductor technology, megavolt voltages combined with gigawatt peak powers have been achieved. This review considers the main physical processes that determine the mechanism of operation of a SOS based on the SOS effect. The principle of operation, design, and characteristics of SOS diodes and SOS generators is described, and prospects for their further development are discussed. Examples are given of using SOS generators in various pulsed power applications such as electron accelerators, X-ray pulse devices, high-power microwave electronics, pumping of gas lasers, and ignition of electrical discharges.

The Bragg element base of the microwave and terahertz electronics

A new approach to constructing the elemental base of electronics in the microwave and terahertz ranges associated with the development of functional elements of radio electronics based on Bragg structures have been proposed. The possibility of creating narrow-band rejection filters based on Bragg structures with a frequency-independent transmission coefficient close to unity outside the stop band has been demonstrated. The characteristics of small-sized matched loads for operation in the microwave and terahertz frequency ranges based on Bragg structures containing nanometer metal films have been described. The possibility of using microwave photonic crystals as a new types of electrodynamic systems for measuring the parameters of materials and structures by microwave methods has been considered. The coaxial photonic crystal was used for implementing the method for measuring the complex permittivity of dielectrics, based on the use of the transmission and reflection frequency dependences at the frequency of the defect mode in the band gap.

Suitable materials selection that act as a retardant agent against microwave radiation and electronics packaging to human life

Recently there is a high attempts to investigate the possibility of protecting human body from microwave radiation and electronics packaging. In this study an electromagnetic radiation shielding film by reflecting and/or absorbing the incident wave were prepared as a promising solution. Basically PVC and iron oxide nanoparticles were synthesized using solution casting method to make the protection film. Analysis via VNA has been conducted to understand the shielding behaviour during the exposure to the radiation. The prepared films exhibit ability of absorbing microwave radiation in the range of 8 GHz – 11 GHz, with a maximum value of -10 dB at 30 wt. % of iron oxide nanoparticle. Furthermore microwave absorption performance can be improved by putting two layers or more in order to increase the thickness of the shield. It is suggested that the results are mainly attributable to good effective properties of iron oxide and their homogeneous dispersion in the PVC matrix, also from the analysis it will propose the optimum solutions for this problem.

The Influence of Substitution with Aluminum on the Field of Effective Magnetic Anisotropy and the Degree of Magnetic Texture of Anisotropic Polycrystalline Hexagonal Ferrites of Barium and Strontium for Substrates of Microstrip Devices of Microwave Electronics

This article discusses the influence of substitution with Al3+ ions on the field of the effective magnetic anisotropy HAeff and the degree of magnetic texture f of anisotropic polycrystalline hexagonal ferrites of barium and strontium. Sample batches are produced by ceramic technology, the texture is formed by compaction in a magnetic field. The preparation of test objects is described in detail. Batches of barium hexaferrites with an ion concentration of Al3+ 0.9, 1.4, 2.5, and 2.6 f.u. and batches of strontium hexaferrites with a concentration of 0.1 f.u. are synthesized. It is demonstrated that the applied procedure makes it possible to obtain barium and strontium hexaferrites with HAeff = 19–35 kE and f = 80–83%. The mentioned values of HAeff and f are sufficient for the production of substrates for microstrip UHV devices of the millimeter wave band. For the first time, it is detected that the degree of the magnetic texture of polycrystalline barium hexaferrites increases with the concentration of Al3+ ions; in addition, a moderate magnetic texture (5.5–5.8%) is observed in isotropic strontium hexaferrites. The experimental results are discussed. The formation mechanism of the magnetic texture in the considered hexaferrites during synthesis is proposed.

Investigation of material properties for polymer-based microwave devices

This work demonstrates that the molding technique for polymer-based flexible microwave electronics with various polymers in order to evaluate acceptable boundaries for conductivity and tan loss. Performance evaluation has been done on the microstrip line and patch antennas with and without material improvements. We have demonstrated that improvements in conductivity after 106 S/m do not give significant benefits. The attenuation in microstrip lines has been reduced from 0.16dB/cm to 0.05dB/cm. However, reduction in the tan loss is able to boost antenna gain from 4.2dBi to 6.5dBi.

Numerical simulation of high-speed AIIIBV photodetectors within drift-diffusion approximation

This paper is focused on a fundamental scientific and technical problem of research and development of high-performance on-chip interconnections for next-generation integrated devices of micro-, nano- and microwave electronics. Previously we proposed an injection laser with functionally integrated optical modulator and double heterostructure, which can be used as an efficient source of light for on-chip optical interconnections. To detect short laser pulses generated by the laser-modulator, a high-speed and technologically compatible photodetector is required. In this paper we develop the non-stationary drift-diffusion model of transient processes in high-speed photodetectors, algorithms of its numerical implementation and applied software intended for one- and two-dimensional simulation of photosensitive optoelectronic devices with various structures. According to the obtained results of drift-diffusion numerical simulation, it is reasonable to research the methods of carrier lifetime reduction in the active regions of photodetectors for on-chip optical interconnections.

SAMEERDU—Digital Ionosonde: Brief System Description and Initial Results from a Low‐Latitude Location Dibrugarh

AbstractA digital ionosonde was designed and built by Society for Applied Microwave Electronics Engineering and Research (SAMEER), Mumbai in collaboration with Dibrugarh University to suit the needs of equatorial‐ and low‐latitude regions of India. The design objectives were to obtain good signal‐to‐noise ratio to mitigate the heavy noise due to interference, obtain short duration ionograms, estimate vertical drifts, reconstruct vertical electron density profile, and make antenna size smaller. Transmission of maximum 1 kW power using modified delta antenna is used with dual channel magnetic loop receiver antenna. Pulse compression by 8‐ and 16‐bit biphase codes are employed to increase noise immunity and the height resolution. The preliminary results of the ionogram mode only are presented in this work. The basic ionogram recorded by this system called SAMEER‐Dibrugarh University Ionospheric Radar is compared with colocated Canadian Advanced Digital Ionosonde ionogram which is in operation in Dibrugarh since 2010. A reasonably clear trace of E and F layers is obtained even without coherent pulse integration and pulse coding. The performance of the coding schemes is investigated with and without coherent integration. Some sample ionospheric experiments conducted with SAMEER‐Dibrugarh University Ionospheric Radar, and interesting results like the detection of travelling ionospheric disturbances, Es layer substructures, ionospheric irregularities, and the generation of bottom‐side vertical electron density profile are presented to highlight the potential and capabilities of the system.

Thermal management of microwave electronics in the radar system

This work aims at improving the state of the art cooling technique for Transmit Receiver Modules (TRMs) by employing the micro channel heat sink technology. The key objectives of this study are to (1) optimize process parameters (Channel width, Channel Height, and Fin width) of heat sink for minimal thermal resistance, (2) conduct numerical simulation of heat sink with optimized parameters, and (3) design and fabricate micro channel heat sink to cool TRMs with heat flux of 100 W/cm2. Taguchi L9 orthogonal array is formulated to optimize the parameters. CFD simulation method is employed to obtain the optimum combination of factors. The optimum combination of factors (Channel height-4 mm, Channel width-0.3 mm and Fin width-0.3 mm) for minimum thermal resistance is found. A heat sink is fabricated with the optimized parameters. Through experimental investigation, the thermal resistance of the fabricated heat sink is determined as 0.0636 °C/W which is found to be capable of cooling TRMs with 100 W/cm2.

Analysis of Metrological Provision Problems of a Test Stand for Testing Radio-Electronic Products for Resistance to Irradiation with High-Energy Heavy Ions

The problems of the metrological certification of beams of high-energy heavy charged particles (HCPs) and protons that will be used in the study—as well as testing for radiation resistance—of promising products of semiconductor micro- and nanoelectronics, solid-state microwave electronics, and micromechanical systems are considered. One of the main requirements for such beams is ensuring the desired range of linear energy transfer (LET). Two methods for changing the LET are considered, one of which is based on using the ions of various types (16O, 22Ne, 40Ar, 56Fe, 84Kr, 136Xe, 209Bi), and the other is based on using ion of the same type (197Au), but with different energies. The advantages of using both methods are considered and the problems arising when using the second method are analyzed.

Spin-wave confinement and coupling in organic-based magnetic nanostructures

Vanadium tetracyanoethylene (V[TCNE]x) is an organic-based ferrimagnet that exhibits robust magnetic ordering (TC of over 600 K), high quality-factor (high-Q) microwave resonance (Q up to 3500), and compatibility with a wide variety of substrates and encapsulation technologies. Here, we substantially expand the potential scope and impact of this emerging material by demonstrating the ability to produce engineered nanostructures with tailored magnetic anisotropy that serve as a platform for the exploration of cavity magnonics, revealing strongly coupled quantum confined standing wave modes that can be tuned into and out of resonance with an applied magnetic field. Specifically, time-domain micromagnetic simulations of these nanostructures faithfully reproduce the experimentally measured spectra, including the quasiuniform mode and higher-order spin-wave (magnon) modes. Finally, when the two dominant magnon modes present in the spectra are brought into resonance by varying the orientation of the in-plane magnetic field, we observe anticrossing behavior, indicating strong coherent coupling between these two magnon modes at room temperature. These results position V[TCNE]x as a leading candidate for the development of coherent magnonics, with potential applications ranging from microwave electronics to quantum information.

Influence of aluminum substitution on the fi eld of effective magnetic anisotropy and the degree of magnetic texture of anisotropic polycrystalline hexagonal ferrites of barium and strontium for substrates of microstrip devices of microwave electronics

Abstract. In this paper, the effect of Al3+ ions substitutions on the value of the effective magnetic anisotropy field НАeff and the degree of magnetic texture f of the anisotropic polycrystalline hexagonal barium and strontium ferrites were studied. The samples were obtained by the ceramic technology method and the texture was formed by pressing in a magnetic field. The sample preparation technology presented in detail. The batches of barium hexaferrites were synthesized with the concentration of Al3+ ions: 0.9; 1.4; 2.5 and 2.6 formula units while strontium hexaferrites had Al3+ concentration of 0.1 formula units. It has been shown that by this technology barium and strontium hexaferrites with high value of (in range of 19—35 kOe) and with f = 80—83% could be obtained. The achieved values of НАeff and f could be sufficient for the production of substrates for microstrip microwave devices in millimeter−wave region.For the first time a raise in the degree of magnetic texture of polycrystalline barium hexaferrites with an increase of concentration of Al3+ ions were detected; a slight (5.5—5.8%) magnetic texture of isotropic strontium hexaferrites was also detected. The achieved results discussed in detail. For studied hexaferrites the mechanism of magnetic texture formation during the process of synthesis is proposed.