Papers by Keyword: Gain

Abstract: This work investigates the radiation pattern of a 5 GHz antenna composed of a metal dipole antenna and surrounded by fluorescent tubes which act as reflectors (plasma medium). The study emphasizes the role of plasma reflectors in improving the antenna’s efficiency by controlling the radiation pattern. The electrical parameters of the plasma medium are modeled by Drude model in Comsol Multyphysics for different voltage discharges. Also, a CST software is used to simulate metallic dipole antenna reconfigurability. The results show that the plasma can be used as a good reflector when its permittivity is negative () and . Moreover, it is shown that with increasing the discharge voltage, the plasma reflectivity increases, this is because the gain increases and the directivity of the antenna considerably changes. Keywords: Reflector, Plasma, COMSOL, CST, Gain, Directivity.

Abstract: The manuscript investigates the leaf-shaped nanostrip-fed graphene plasmonic nanopatch on a silicon dioxide surface for optical near-field applications. The dispersion properties of graphene and silicon dioxide are demonstrated through Drude and Lorentz modeling to examine the suitability of the materials for the plasmonic nano-antenna design. The nano-antenna parameters T_SUB (substrate thickness), W (width of the nanostrip feed line) and R_L (nano-antenna size) are adjusted to modify the plasmonic resonance frequency from 7.9 THz to 40.9 THz. The proposed leaf-shaped nanostrip-fed graphene plasmonic nanopatch exhibits a reflection of -43.27 dB at 36 THz with a gain of 8.19 dB at T_SUB =125 nm, W = 40 nm and R_L = 50 nm.

Abstract: Wind power has many benefits over other energy sources, including a high power density and an outstanding return on investment. However, there are some drawbacks, such as intermittent output power and the need for periodic maintenance. As a result, its output is substantially variable, making it difficult to predict and potentially causing system instability. Therefore, to model such a source, it is necessary to model the dynamic behavior of the wind turbine generator as well as the characteristics of the wind speed to capture the fluctuations. Furthermore, the durability and efficiency of the wind energy conversion system (WECS) are wholly dependent on the quality of the control strategy employed. In this paper, we introduced a control scheme, which makes it possible to find an optimal solution to the control problem while at the same time operating within the constraint point. Therefore, we designed the Model Predictive Controller to control and smoothly transition the wind turbine in all its operating modes while complying with its constraints. The main objective of using this control technique is to maximize power production while keeping the control action as simple as possible. The WECS used in this study is the horizontal axis wind turbines (HAWT), which are easier to control as their dynamics are not so complicated to model and, at the same time, produce maximum output power. The controller works have to adapt in the same way as the control goals are different for different wind speeds. Gain and weight scheduling strategies are used to design a control system that allows smooth transitioning between control regions. The dynamics of the wind turbine system and the controller are designed and simulated by the MATLAB / Simulink environment.

Abstract: An ice crossing is a road constructed on an ice-covered river, organized in the absence of a bridge, as well as in view of the impossibility of a ferry crossing in winter due to the formation of ice cover on water bodies. For most of the regions of Russia, in the cold season, the establishment of negative temperatures is typical, as a result of which ice crossing is a common transport facility. So, in the country annually opens more than 500 crossings, about 20 of which are located in the Perm Krai. Their opening takes place in December - early January, and closing - in late March - early April. The easiest way to arrange crossings is on natural ice, as a result of which their carrying capacity increases as the natural thickness of the ice increases. Because of this, the passing of heavy vehicles is possible only in January – February, which is a significant drawback. Today, there are several ways to artificially increase the carrying capacity, which include reinforcing the ice sheet with geosynthetic material. This method is a new and rather promising direction in road construction due to the reusable use of geomeshs. The article discusses the dependence of changes in the characteristics of the ice cover on the applied geosynthetic material, as well as technological and economic comparison of reinforcement variants. To this end, materials were collected on organized crossings of the Perm Krai, possible types of geomeshs were examined, and calculations were carried out to determine the carrying capacity of the crossing. This reinforcement method contributes to the earlier passage of heavy vehicles at the crossing, and also improves the safety of traffic on it and prolongs its service life.

Abstract: Wide bandgap semiconductors, such as 4H SiC, are suitable for power regulating devices, due to compatibility with conventional process integration, high breakdown voltage and thermal conductivity [1]. For RF applications, in order to achieve better switching speed, high cut off frequency, and low series resistance (Rdson), it is essential to choose the right gate metals [2]. Engineering of the gate metals not only improves the critical device parameters by adjustment of the metal workfunction, but also affects how the high aspect ratio trenches are filled for a next generation SIT device configuration [3] - [5].

Abstract: The 4H-SiC ultraviolet detector of the MESFET structure with gain is proposed and simulated in this paper. The Schottky gate of MESFET is transparent or semi-transparent to allow more of the incident UV light to be absorbed in the device. The effect of the doping and thickness of the channel layer on the photocurrent of the 4H-SiC MESFET UV detector is simulated and the effect mechanism is analyzed. The simulation results show that the 4H-SiC MESFET exhibits photocurrent below 380 nm. And only when the channel of the 4H-SiC MESFET is in the open state there will be a gain in the detector. Shorter gate length is beneficial to improve the responsivity and the gain of the 4H-SiC MESFET UV detector. When the gate length is set to 10 μm with the channel thickness of 0.3 μm and channel doping of 1×10¹⁷ cm^-3, the peak responsivity and the gain are calculated to be 12.9 A/W and 55.6 respectively.

Abstract: This paper investigate the radiation efficiency enhancement for a small square patch resonator with the integration of single layer circular split ring metasurface mirror (CSRMM) operating at 5.8 GHz using Transmission Line Matrix (TLM) method. The single layer CSRMM provide an appropriate reflection phase to act as a mirror and is able to enhance the resonator gain and efficiency. This work shows a linear phase response from 5.8 GHz to 5.9929 GHz that is sufficient for 50 Ω wireless communication system operation. A siginificant improvement of 0.391 to 0.741 dBi IEEE gain over the whole frequency range was demonstrated. The resonator has an initial radiation efficiency of 0.246 and incremented to 0.406 once CSRMM is inserted. The resonator small size configuration provides adequate space for mounting the mirror close to the resonator, making it more fitting for modern wireless devices.

Abstract: In this paper, the simulation and measurement results of a filter-antenna module for application in WLAN band are presented. The filter-antenna module is fabricated on microwave ceramic substrate. The filter-antenna module is consisted of a monopole antenna, two U-shaped microstrip half wavelength resonators, and a tapped open stub. The proposed filter-antenna module has good agreement between the measurement and the simulation results. At center frequency, electromagnetic coupling between two half-wavelength resonators and inverted-L shaped microstrip feed line occurs and contributes the radiation. At the harmonic frequency, the currents are mainly distributed around the tapped open stub. The proposed filter-antenna module has a 10 dB return loss with bandwidth 290 MHz (2,337 - 2,627 MHz), covering the WLAN band.

Abstract: Based on the magnetic materials (JV-5) substrate, Double L-shaped slot microstrip antenna is designed. The bandwidth is over 2 times that of the normal substrate and a 40% reduction in size happens.. On this basis, the microstrip antenna with magnetic substrate EBG structure is designed and the EBG structure uses the corrosive effects of joint floor, namely getting periodic H-shaped and circular structures by the floor corrosion, and performing a simulation with HFSS14.0. The results show that the EBG structure of magnetic material having a prominent advantage of the miniaturization and bandwidth-broaden compared to a microstrip antenna with non-magnetic materials substrate, resulting in more than 10% relative bandwidth and a slight gain loss. To some degree, introducing EBG structure can reduce the size of the antenna and increase its bandwidth, and it also improve the gain and radiation characteristics of the antenna.Key words: EBG structure; magnetic material;Double L-shaped slot microstrip antenna; gain

Abstract: The split ring resonators (SRR) is designed to work at X band and its equivalent medium parameters are estimated by using the equivalent analysis method. The high gain microstrip antenna, which is based on Photonic BandGap (PBG) structure, is also studied. To make the scattering wave deviates mirror direction and reduce the out-band Radar Cross Section (RCS) without affecting the performance of antenna, the designed SRR is used as the cover of PBG structure microstrip antenna. The results show that the forward gain of PBG structure antenna is 0.8 dB higher than the tradition antenna. After the SRR covers on the PBG structure antenna, the gain of antenna is unchanged and the RCS of the mirror direction decreases for all incident angles, and the most decrement is 21.05 dB.