Carbon nanotubes composite materials for dipole antennas at terahertz range

This paper aims to present two types of carbon nanotubes composite materials (CNTs-composite) for antenna applications within terahertz (THz) frequency band. These composite materials consist of CNTs coated by copper and silver, separately, to construct CNTs-copper and CNTs-silver composite materials, respectively. The comparisons between the dipole antennas of these structure materials with CNTs dipole antenna and copper dipole antenna are presented to exhibit performance evaluation of the presented new dipole antennas. The mathematical modeling of CNTs-composite material is presented in this paper. The results obtained from the comparisons CNTs-copper and CNTs-silver dipole antennas are presented based on S 11 parameters, gain and efficiency

Electromagnetic modelling of bundle of single-walled carbon nanotubes with circular geometry for antenna applications

This paper aims to present an effective electromagnetic (EM) modelling approach for circular bundle of single-walled carbon nanotubes (CBSWCNTs), based on the electrical conductivity, relative complex permittivity and linear distribution impedance by applying General Ohms law for this bundle. The equivalent single conductor material (ESCM) model for personification the CB-SWCNTs is presented in this paper. The main target of this modelling approach is to estimate and investigate the EM properties of CBSWCNTs using common EM engineering tool solver CST (MWS). For this purpose, the CB-SWCNTs and ESCM dipole antennas will be designed and implemented using CST (MWS). Mathematically, the equivalent conductivity model, relative complex permittivity and other parameters of the CB-SWCNTs will be derived in this paper and considered as equivalent material parameters for the ESCM. This modelling technique is expected to provide new avenues for designing different antenna structures

Reduction of cavity length dependence and improvement of characteristics of 1.55 µm quantum dot based LASER using Indium Nitride

This paper presents the improvement of certain important characteristics of 1.55 µm laser by reducing the dependence of cavity length using InN based quantum dot in the active layer of the device structure. The improvement of these characteristics has been investigated in terms of ultra low threshold current density, minimization of internal loss, enhancement of the modal gain, external differential efficiency and the photon lifetime. In this paper these characteristics have been investigated using InN based quantum dot in the active layer of the laser structure and compared with GaN and AlN based quantum dot laser. The comparison results reveal that InN based quantum dot provides lower threshold current density, reduced internal loss compared to GaN and AlN quantum dot based laser. Beside these enhanced modal gain, improved efficiency and higher photon lifetime have also been reported using InN based quantum dot in the active layer of the laser structure. In addition to these improvements obtained from the numerical results it is ascertained that InN based quantum dot in the active layer of the laser structure offers weaker dependence of cavity length on these characteristics. From the results it is revealed that InN can be a promising material to design high performance quantum dot based laser operating at 1.55 µm with reduced cavity length dependence in the very near future

A COMPARATIVE ANALYSIS OF THE EFFECT OF TEMPERATURE ON BAND-GAP ENERGY OF GALLIUM NITRIDE AND ITS STABILITY BEYOND ROOM TEMPERATURE USING BOSE–EINSTEIN MODEL AND VARSHNI’S MODEL

High temperature stability of band-gap energy of active layer material of a semiconductor device is one of the major challenges in the field of semiconductor optoelectronic device design. It is essential to ensure the stability in different band-gap energy dependent characteristics of the semiconductor material used to fabricate these devices either directly or indirectly. Different models have been widely used to analyze the band-gap energy dependent characteristics at different temperatures. The most commonly used methods to analyze the temperature dependence of band-gap energy of semiconductor materials are: Passler model, Bose–Einstein model and Varshni’s model. This paper is going to report the limitation of the Bose–Einstein model through a comparative analysis between Bose–Einstein model and Varshni’s model. The numerical analysis is carried out considering GaN as it is one of the most widely used semiconductor materials all over the world. From the numerical results it is ascertained that below the temperature of 95o K both the models show almost same characteristics. However beyond 95o K Varshni’s model shows weaker temperature dependence than that of Bose–Einstein model. Varshni’s model shows that the band-gap energy of GaN at 300o K is found to be 3.43eV, which establishes a good agreement with the theoretically calculated band-gap energy of GaN for operating at room temperature

Parameters extraction of unified power quality conditioner on the calculation of a membership function

The Unified Power Quality Conditioner (UPQC) has the capability of improving power quality in the industrial distribution systems. It is a combination of shunt and series active power filters, both joined together by a common Direct current (DC) bus. The major issue when utilizing the UPQC is the determination of the optimal parameters. The traditional method used to determine the optimal parameters of the UPQC is a daunting task, because the system requires greater computational and simulation efforts. This paper proposes a faster approach using the concept of a Membership Function (MF) in which a Weight Factor (WF) is utilized. In the proposed technique, a range of values is specified for each parameter of the filters. These values are used to design a membership function for each parameter, and the choice of the optimal parameter is extracted by the aid of a WF. In this study, the effectiveness of the UPQC was tested at various system conditions to verify the performance of the proposed technique. The presented results show that the obtained parameters of UPQC using the proposed technique can provide fast dynamic response

Bandwidth enhancement at microstrip patch antenna using modified EC-SRR structures

The research explores the effect of modified Edge Couple Split Ring Resonator (EC-SRR) on the wideband microstrip patch antenna. Firstly, there are three different size of the EC-SRR, namely larger EC-SRR, normal EC-SRR and smaller EC-SRR had been structured first before located into the patch antenna. After that, a simple microstrip patch antenna of Design A had been simulated using the CST Microwave Studio software. Then, the addition of different number of modified EC-SRR on the side and above side of the patch. Beside the basic design of Design A, three different stages of addition of SRR are considered in this research. Design B, Design C and Design D consist of SRR addition at the edges, sides and above of patch. The wideband antenna resonates between 2.08 GHz to 3.45 GHz of frequency with-24.271 dB of return loss at resonant frequency of 3.11 GHz. At 2.4 GHz of WLAN application, the return loss is-15.154 dB. Design D shows the increment of the bandwidth compare all designs with 1.372 GHz (from 2.077 GHz 3.449 GHz) compare with Design A with only 0.645 GHz (from 2.307 GHz to 2.952 GHz)

Improvement of temperature dependence of carrier characteristics of quantum dot solar cell using InN quantum dot

Improvements of temperature dependence of certain characteristics of quantum dot solar cell using InN as active material of the device structure has been reported in this paper. A numerical analysis of temperature dependence of different parametric characteristics related to carriers within a quantum dot solar cell has been carried out in this research work. Numerical analysis of these solar cell features have been performed using Group-III Nitride trios namely GaN, AlN and InN quantum dot as active layer material of solar cell structure. Among different parameters of quantum dot solar cell drift length and the diffusion length have been analyzed along with the power loss of the carriers to complete the whole process. In this present research work effect of temperature on the characteristics of these parameters has been analyzed using mathematical approach. Numerical results obtained are compared for preferential outcomes. It is revealed from the comparison results that only the drift length of the carrier has been increased but the diffusion length and the power loss of the carriers have been minimized using InN quantum dot in the active layer of solar cell. Hence InN is the auspicious material to fabricate solar cell in upcoming decades

Quadruple band MIMO dielectric resonator antenna for 5G SUB-6 GHz applications

A quadruple band with L-slotted multiple-input-multiple-output (MIMO) square dielectric resonator antenna (SDRA) for fifth generation (5G) applications at the sub-6 GHz band is presented, which can cover 5G new radio band N77 (3.3–4.2) GHz and N79 (4.4–5) GHz. The proposed structure consists of a single SDRA mounted on a substrate excited by an aperture slot underneath dielectric resonators (DR)s. The performance of SDRA is improved by introducing L-shaped slot on the central part of DRA. Results show that the MIMO SDRA antenna achieves S11\u3c-10 dB and S21\u3c=-15 dB for all resonant frequencies at 3.5 GHz, 4 GHz, 4.6 GHz, and 5 GHz, indicating good performance of the antenna at the desired frequencies. The maximum realized gain is 5.61 dB and 5.01 dB at port 1, 4 GHz and port 2, 4.6 GHz, respectively. The radiation efficiencies are acceptable for all resonant frequencies. Moreover, the proposed antenna design achieved good envelop correlation coefficient (ECC) and diversity gain (DG) at the desired frequencies. Thus, the antenna can be used for 5G sub-6 GHz applications

Design of multiple-layer microwave absorbing structure based on rice husk and carbon nanotubes

This paper presents a multiple-layered microwave absorber using rice husk and carbon nanotube composite. The dielectric properties of each layer composite were measured and analysed. The different layer of microwave absorber enables to control the microwave absorption performance. The microwave absorption performances are demonstrated through measurements of reflectivity over the frequency range 2¿18 GHz. An improvement of microwave absorption \u3c¿20 dB is observed with respect to a high lossy composite placed at bottom layer of multiple layers. Reflectivity evaluations indicate that the composites display a great potential application as wideband electromagnetic wave absorbers

Improvement of temperature dependence of carrier characteristics of quantum dot solar cell using InN quantum dot

Improvements of temperature dependence of certain characteristics of quantum dot solar cell using InN as active material of the device structure has been reported in this paper. A numerical analysis of temperature dependence of different parametric characteristics related to carriers within a quantum dot solar cell has been carried out in this research work. Numerical analysis of these solar cell features have been performed using Group-III Nitride trios namely GaN, AlN and InN quantum dot as active layer material of solar cell structure. Among different parameters of quantum dot solar cell: drift length and the diffusion length have been analyzed along with the power loss of the carriers to complete the whole process. In this present research work effect of temperature on the characteristics of these parameters has been analyzed using mathematical approach. Numerical results obtained are compared for preferential outcomes. It is revealed from the comparison results that only the drift length of the carrier has been increased but the diffusion length and the power loss of the carriers have been minimized using InN quantum dot in the active layer of solar cell. Hence InN is the auspicious material to fabricate solar cell in upcoming decades