High Gain Factor Research Articles

A configuration to double the gain of pyramidal horn antenna using single layer frequency selective surface

AbstractA gain enhancement technique in pyramidal horn antenna using a slot type band pass frequency selective surface (FSS) is presented. The horn antenna without FSS has achieved a measured gain of 10.5 dBi at 10 GHz, while the antenna with the single layer slotted FSS yields an enhanced measured gain of 14.2 dBi (an improvement of 3.7 dB or 134%). Conventionally, such a gain enhancement would 5 times increase in its dimensions (flaring). However, the authors achieve the same with only 2 times increase in dimensions. Another interesting value addition of the proposed idea is that an FSS sheet can be added to the existing horn antenna to increase its gain without altering the antenna itself. Such a scheme is highly beneficial in strategic applications. The proposed gain enhanced horn antenna can be recommended to be utilised in several X‐band applications, such as radar systems (weather, surveillance, traffic control and military), satellite communications and point–point microwave links that require high gain and small form factor.

Gain and lasing from CdSe/CdS nanoplatelet stripe waveguides

Colloidal semiconducting nanocrystals are efficient, stable and spectrally tunable emitters, but achievable optical gain is often limited by fast nonradiative processes. These processes are strongly suppressed in slab-shaped nanocrystals (nanoplatelets), due to relaxed exciton Coulomb interaction. Here, we show that CdSe/CdS nanoplatelets can be engineered into (sub)microscopic stripe waveguides that achieve lasing without further components for feedback, i.e., just relying on the stripe end reflection. We find a remarkably high gain factor for the CdSe/CdS nanoplatelets of 1630 cm −1 . In addition, by comparison with numerical simulations we assign a distinct emission peak broadening above laser threshold to emission pulse shortening. Our results illustrate the feasibility of geometrically simple monolithic microscale nanoplatelet lasers as an attractive option for a variety of photonic applications. • Colloidal nanoplatelets are engineered into simple monolithic stripe waveguides that show lasing. • We find a remarkably high gain of about 1630 cm −1 , as measured for the stripe waveguides. • The waveguide lasers show an emission peak broadening above laser threshold due to pulse shortening.

The Blade Edge-Shaped Microstrip Antenna for X Band Applications

In this paper, a simple design of a microstrip patch antenna with a blade edge shape is proposed. It is based on annular rings with blade-shaped edges. The antenna has a wide range of applications in the X band such as terrestrial, radar, satellite communication,wave-guide probing and etc. The model antenna has a compact structure with a size of 25 × 20 mm2 and is etched over the FR-4 ( = 4.54). The design is simulated in Computer Simulation Technology, CST software-Microwave Studio. The proposed antenna offers a stable radiation pattern, a high gain factor, and a reduced lobe level. Sharp edges of antenna elements increase the antenna activity scale in the X band.

A novel signal conditioning system for SODAR

The sonic detection and ranging (SODAR) instrument is widely used for measuring the atmospheric boundary layer (ABL). SODAR operates on an acoustic principle and creates an ABL structure using air-backscattered signals. These signals have extremely low amplitude and are highly susceptible to environmental noise. In this paper, a novel signal conditioning circuit with high gain, low noise, and high quality factor (Q) has been designed for the preamplifier of SODAR. This signal conditioning circuit is comprised of an ultra-low noise amplifier and a dual-amplifier band-pass filter. The designed preamplifier circuit is implemented with SODAR at the CSIR-National Physical Laboratory in New Delhi. The electrical characteristics of the proposed system are compared to the existing design of a single low-noise amplifier and state variable filter. The gain and signal-to-noise ratio performance of the designed preamplifier circuit are significantly improved in comparison to the existing one.

Optical signal denoising through temporal passive amplification

Mitigating the stochastic noise introduced during the generation, transmission, and detection of temporal optical waveforms remains a significant challenge across many applications, including radio-frequency photonics, light-based telecommunications, spectroscopy, etc. The problem is particularly difficult for the weak-intensity signals often found in practice. Active amplification worsens the signal-to-noise ratio, whereas noise mitigation based on optical bandpass filtering attenuates further the waveform of interest. Additionally, current optical filtering approaches are not optimal for signal bandwidths narrower than just a few GHz. We propose a versatile concept for simultaneous amplification and noise mitigation of temporal waveforms, here successfully demonstrated on optical signals with bandwidths spanning several orders of magnitude, from the kHz to GHz scale. The concept is based on lossless temporal sampling of the incoming coherent waveform through Talbot processing. By reaching high gain factors (>100), we show the recovery of ultra-weak optical signals, with power levels below the detector threshold, additionally buried under a much stronger noise background. The method is inherently self-tracking, a capability demonstrated by simultaneously denoising four data signals in a dense wavelength division multiplexing scheme.

Ion‐Accumulation‐Induced Charge Tunneling for High Gain Factor in P–I–N‐Structured Perovskite CH3NH3PbI3 X‐Ray Detector

AbstractLead halide perovskite‐based X‐ray detectors show very promising sensitivity and low detection limit, which can be used for next‐generation, room‐temperature radiation detections. It is interesting to find that the diode‐structured X‐ray detector shows very high photocurrent gain under small reversed bias voltage, which is unusual and should be investigated and understood for better device design. In this regard, a lead halide perovskite‐based X‐ray detector with the p–i–n structure is fabricated and studied. The p–i–n structured device shows abnormal and excellent photoconductor properties with high photocurrent gain factor under reverse bias. Further device simulation reveals that the ion migration and accumulation in the perovskite material are responsible for the large band‐bending at the interface, which may induce charge tunneling to reduce the contact resistance and causes the reverse‐biased device to work as a photoconductor rather than a photodiode. This finding provides a new approach to the understanding and design of high‐performance X‐ray detectors utilizing ionic semiconductors like lead halide perovskites.

Синхронизация генераторов на ЛПД импульсного и непрерывного действия в мм-диапазоне длин волн. Часть 1. Конструкции генераторов и обобщенная модель их синхронизации внешним сигналом

Advances in the development of ultrahigh-frequency semiconductor electronics open wide opportunities for developing optimal schemes and designs of microwave power sources in the millimeter wavelength range providing high stability of the frequency and electromagnetic oscillation phase. Synchronized diode generators used in transmit/receive module for active phased array antennas, coherent low-power radar stations, etc. show great promise. The mode of external synchronization of semiconductor generators allows effectively implementing the task of creating output stages of the transmitters with high gain factor, low frequency noise and an output power level corresponding to the maximum power mode. This article presents the first of two parts of the study, which summarizes the results achieved so far in the development of synchronized oscillators based on impact ionization avalanche transit-time (IMPATT) diodes. The first part presents the electrodynamic designs of the oscillators, which are synchronized with an external source of microwave oscillations and contain a resonant oscillating system with a silicon IMPATT diode. The silicon two-drift IMPATT diode was chosen as an active element due to the fact that its use allows reaching significant levels of pulsed microwave power – an order of magnitude higher than those of the most well-known HEMT and pHEMT transistors in the millimeter wavelength range. It is shown that to reduce losses, the oscillating system should be made in the form of a radial resonator with a diode casing, which has distributed parameters. This eliminates the use of additional reactive inhomogeneities in the initial cross-section of the waveguide section of the generator. Due to the low quality factor of the resonant casing of the diode, the generalized quality factor of the microwave circuit takes the minimum value required to implement a stable generator synchronization process in the millimeter wavelength range. The second part of the work will be devoted to synchronized pulse generators with an output power of 20–150 W.

ACCORDANT: A domain specific-model and DevOps approach for big data analytics architectures

Big data analytics (BDA) applications use machine learning algorithms to extract valuable insights from large, fast, and heterogeneous data sources. New software engineering challenges for BDA applications include ensuring performance levels of data-driven algorithms even in the presence of large data volume, velocity, and variety (3Vs). BDA software complexity frequently leads to delayed deployments, longer development cycles, and challenging performance assessment. This paper proposes a Domain-Specific Model (DSM), and DevOps practices to design, deploy, and monitor performance metrics in BDA applications. Our proposal includes a design process, and a framework to define architectural inputs, software components, and deployment strategies through integrated high-level abstractions to enable QS monitoring. We evaluate our approach with four use cases from different domains to demonstrate a high level of generalization. Our results show a shorter deployment and monitoring times, and a higher gain factor per iteration compared to similar approaches.

3D printing of gaseous radiation detectors

Additive manufacturing techniques such as 3D printing offer unprecedented flexibility in realising intricate geometries. Fused-filament fabrication and high-precision inkjet 3D printing of metals and polymers was used to create functional composite structures, which were operated as radiation detectors. Electron avalanche multiplication in a 3D printed structure was achieved. We present an ionisation chamber and a coarse 2D readout anode with orthogonal strips, which were printed with PLA and graphite-loaded PLA . High-resolution inkjet 3D printing was used to create a Thick Gaseous Electron Multiplier (THGEM) . This represents the first realisation of a fully 3D printed structure achieving electron multiplication. Optical readout was used to quantify the gain factor of the structure and an image under X-ray irradiation was acquired. While the hole geometry of this prototype device inhibited high gain factors, it demonstrates that additive manufacturing is a viable approach for creating detector structures. The conventional manufacturing approach by photolithographic techniques will continue to dominate large size and volume production of MicroPattern Gaseous Detectors (MPGDs) but prototyping and results-driven detector optimisation may greatly benefit from the cost and time-effectiveness of 3D printing.

Hot-Pressed CsPbBr3 Quasi-Monocrystalline Film for Sensitive Direct X-ray Detection.

An X-ray detector with high sensitivity would be able to increase the generated signal and reduce the dose rate; thus, this type of detector is beneficial for applications such as medical imaging and product inspection. The inorganic lead halide perovskite CsPbBr3 possesses relatively larger density and a higher atomic number in contrast to its hybrid counterpart. Therefore, it is expected to provide high detection sensitivity for X-rays; however, it has rarely been studied as a direct X-ray detector. Here, a hot-pressing method is employed to fabricate thick quasi-monocrystalline CsPbBr3 films, and a record sensitivity of 55 684 µC Gyair -1 cm-2 is achieved, surpassing all other X-ray detectors (direct and indirect). The hot-pressing method is simple and produces thick quasi-monocrystalline CsPbBr3 films with uniform orientations. The high crystalline quality of the CsPbBr3 films and the formation of self-formed shallow bromide vacancy defects during the high-temperature process result in a large µτ product and, therefore, a high photoconductivity gain factor and high detection sensitivity. The detectors also exhibit relatively fast response speed, negligible baseline drift, and good stability, making a CsPbBr3 X-ray detector extremely competitive for high-contrast X-ray detections.

A Low-Profile Multilayer Cylindrical Segment Fractal Dielectric Resonator Antenna: Usage for wideband applications

Until the 1980s, shielded dielectric resonators (DRs) were used as high-quality factor energy storage devices for filter and oscillator applications [1]. Later, they gained status as effective radiators due to the efforts of Long, McAllister, and Chen [2]. Since then, enormous DR antenna (DRA) designs have been explored and different feeding techniques introduced to achieve optimum antenna characteristics like high gain and low quality factor (Q-factor), etc. Compared to microstrip antennas, DRAs offer attractive features such as low loss, high efficiency, and wide impedance bandwidth (BW). Low-profile design and BW enhancement are two important aspects of effective antenna synthesis. Various BW enhancement techniques-like the compact slot DRA [3], aperture feeding, perturbation, cavity-backed disk, ring-shaped DRA, and the stacking of two or more dielectric layers [4]-can be applied on DRAs for this purpose. The stacked DRA, dual-segment, hybrid DRA, and slots in ground-plane approaches were also well suited to improve the impedance BW of DRA [5]-[10]. Various multilayer cylindrical DRA (MCDRA) structures have been proposed and investigated for BW enhancement like the stacked cylinder approach [11], [12], slotted coaxial layered structure [13], etc. More recently, various fractal geometries have been introduced for antenna applications. The main objective of fractal applications is to reduce the size of the antenna for wideband characteristics, while maintaining other design parameters at an acceptable level. Several antenna configurations based on fractal geometries have been previously examined [14].

High Gain Power Generation Based On Hybrid Renewable Energy for AC Load Application

This study presents the distributed energy source based current fed inverter has generated high voltage with less passive elements. The hybrid renewable energy generation such as solar and wind has used. The single stage power generation based switched inverter has combined characteristics of both impedance source inverter and switched boost inverter. In conventional voltage source inverter has less boost ability and high electromagnetic noise immunity to the modified current fed inverter circuit. The single diode photovoltaic model and wind-based energy generation have fed into current fed switched inverter for improving high gain and high power factor. The maximum power point tracking such as incremental conductance algorithm has fast-tracking of solar power and generates continuous power to the inverter circuit. 12V solar power and wind power is designed for dc power production, and the output of dc link capacitor is 118V using current fed switched inverter. The current fed switched inverter is designed and implemented in MATLAB/Simulink environment.

Harmonic background amplification in long asymmetrical high voltage cable systems

This paper presents an analysis of a harmonic problem encountered on the Danish island of Anholt and its mitigation. Time synchronized power quality measurements are presented at transmission and island nodes. Harmonic phase gain factors are calculated from the transmission system to the island and a simulation model is constructed and used to explain the reason for the very high gain factors encountered. A resonance problem is identified and a recommendation is made for the use of phase-domain modelling for long asymmetrical cable systems. At the end of the paper, a harmonic filter design process is presented.

A Solar-Blind UV Detector Based on Graphene-Microcrystalline Diamond Heterojunctions.

An ultraviolet detector is demonstrated through a whole-wafer, thin diamond film transfer process to realize the heterojunction between graphene and microcrystalline diamond (MCD). Conventional direct transfer processes fail to deposit graphene onto the top surface of the MCD film. However, it is found that the 2 µm thick MCD diamond film can be easily peeled off from the growth silicon substrate to expose its smooth backside for the graphene transfer process for high-quality graphene/MCD heterojunctions. A vertical graphene/MCD/metal structure is constructed as the photodiode device using graphene as the transparent top electrode for solar-blind ultraviolet sensing with high responsivity and gain factor. As such, this material system and device architecture could serve as the platform for next-generation optoelectronic systems.

Single-Stage Grid-Connected Flyback Microinverter Operating in DCM for Photovoltaic AC Modules

this paper, a single-stage grid-connected flyback microinverter is proposed. The proposed flyback microinverter has some advantages such as high voltage gain, high efficiency, low cost, small size, simple control and high power factor. The proposed system is used to connect the PV panel to the grid with achieving maximum Power Point Tracking (MPPT) control. The converter operates in DCM to inject a sinusoidal current into the grid with unity power factor. A complete system has been simulated using PSIM program. The simulation results are obtained to validate the system. Keywords-Stage, grid-connected, Microinverter, Flyback, DCM, MPPT.

Investigation of L10 FePt-based soft/hard composite bit-patterned media by micromagnetic simulation**Project supported by the National Natural Science Foundation of China (Grant Nos. 51171086 and 61272076) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61003041).

The soft/hard composite patterned media have potential to be the next generation of magnetic recording, but the composing modes of soft and hard materials have not been investigated systematically. L10 FePt-based soft/hard composite patterned media with an anisotropic constant distribution are studied by micromagnetic simulation. Square arrays and hexagonal arrays with various pitch sizes are simulated for two composing types: the soft layer that encloses the hard dots and the soft layer that covers the whole surface. It is found that the soft material can reduce the switching fields of bits effectively for all models. Compared with the first type, the second type of models possess low switching fields, narrow switching field distributions, and high gain factors due to the introduction of inter-bit exchange coupling. Furthermore, the readout waveforms of the second type are not deteriorated by the inter-bit soft layers. Since the recording density of hexagonal arrays are higher than that of square arrays with the same center-to-center distances, the readout waveforms of hexagonal arrays are a little worse, although other simulation results are similar for these two arrays.

Zero dynamics and funnel control for linear electrical circuits

We consider electrical circuits containing linear resistances, capacitances and inductances. The circuits can be described by differential-algebraic input–output systems, where the input consists of voltages of voltage sources and currents of current sources and the output consists of currents of voltage sources and voltages of current sources. We generalize a characterization of asymptotic stability of the circuit and give sufficient topological criteria for its invariant zeros being located in the open left half-plane. We show that asymptotic stability of the zero dynamics can be characterized by means of the interconnectivity of the circuit and that it implies that the circuit is high-gain stabilizable with any positive high-gain factor. Thereafter we consider the output regulation problem for electrical circuits by funnel control. We show that for circuits with asymptotically stable zero dynamics, the funnel controller achieves tracking of a class of reference signals within a pre-specified funnel; this means in particular that the transient behavior of the output error can be prescribed and the funnel controller does neither incorporate any internal model for the reference signals nor any identification mechanism, it is simple in its design. The results are illustrated by a simulation of a discretized transmission line.

Beef Marbling Image Segmentation Based on Homomorphic Filtering

In order to reduce the influence of uneven illumination and reflect light for beef accurate segmentation, a beef marbling segmentation method based on homomorphic filtering was introduced. Aiming at the beef rib-eye region images in the frequency domain, homomorphic filter was used for enhancing gray, R, G and B 4 chroma images. Then the impact of high frequency /low frequency gain factors on the accuracy of beef marbling segmentation was investigated. Appropriate values of gain factors were determined by the error rate of beef marbling segmentation, and the results of error rate were analyzed comparing to the results without homomorphic filtering. The experimental results show that the error rates of beef marbling segmentation was remarkably reduced with low frequency gain factor of 0.6 and high frequency gain factor of 1.425; Compared with other chroma images, the average error rate (5.38%) of marbling segmentation in G chroma image was lowest; Compared to the result without homomorphic filtering, the average error rate in G chroma image has decreased by 3.73%.

Two-channel pulse synthesis to overcome gain narrowing in femtosecond fiber amplifiers

We demonstrate spectral coherent beam combining of two femtosecond fiber chirped-pulse amplifiers seeded by a common oscillator. Using active phase stabilization based on an electro-optic phase modulator, an average power of 10 W before compression and a high gain factor of 30 dB are obtained. At this gain value, 130 fs pulses with a spectral width of 19 nm can be generated, highlighting the strong potential of pulse synthesis for the reduction of the minimum duration of ultrashort pulses in fiber chirped-pulse amplifiers.

Apodization of chirped quasi-phasematching devices

Chirped quasi-phasematching (QPM) optical devices offer the potential for ultrawide bandwidths, high conversion efficiencies, and high amplification factors across the transparency range of QPM media. In order to properly take advantage of these devices, apodization schemes are required. We study apodization in detail for many regimes of interest, including low-gain difference frequency generation (DFG), high-gain optical parametric amplification (OPA), and high-efficiency adiabatic frequency conversion (AFC). Our analysis is also applicable to second-harmonic generation, sum frequency generation, and optical rectification. In each case, a systematic and optimized approach to grating construction is provided, and different apodization techniques are compared where appropriate. We find that nonlinear chirp apodization, where the poling period is varied smoothly, monotonically, and rapidly at the edges of the device, offers the best performance. We consider the full spatial structure of the QPM gratings in our simulations, but utilize the first order QPM approximation to obtain analytical and semi-analytical results. One application of our results is optical parametric chirped pulse amplification; we show that special care must be taken in this case to obtain high gain factors while maintaining a flat gain spectrum.