Analytic Estimation of Two-Dimensional Electron Gas Density and Current-Voltage Characteristic in AlGaN/GaN HEMT’s

This paper is mainly dedicated to understand the phenomena governing the formation of two-dimensional electron gas (2DEG) confined in the quantum well which hold the role of the channel in the high electron density transistors (HEMT) based on AlGaN / GaN heterojunction. The theory takes into account: the crystal structure, the spontaneous and piezoelectric polarization concept, the formation mechanism of two-dimensional electron gas at the AlGaN / GaN interface, the approximate resolution of the Poisson and Schrödinger equations to determine the density of Two-dimensional electron gas after the analytical formula of the current-voltage characteristic is established. Our study is also concerned with the dependence of the two-dimensional electron gas density on the following technological parameters: Aluminum molare fraction, AlGaN layer thickness and AlGaN layer doping, In order to control the influence of these parameters on the device performance. Finally, the current-voltage characteristic which reflects the variation of the drain-source current as a function of the modulation of the gate voltage has been discussed

New investigation of an E-mode metal-insulator-semiconductor AlInN/AlN/GaN HEMT with an Au-T-gate

In a high electron mobility transistor (HEMT), the density of the two-dimensional electron gas (2DEG) channel is modulated by the application of a bias to a Schottky metal gate. These devices are depletion mode (D-mode), which means that a negative bias must be applied to the gate to deplete the electron channel and turn. The most challenging aspect in the present research activity on based-GaN devices is the development of a reliable way to achieve an enhancement-mode (E-mode) HEMT. Enhancement-mode GaN HEMTs would offer a simplified circuitry by eliminating the negative power supply. In this work, the aim is to investigate the different techniques which can influence the threshold voltage and shift it to a positive value. A novel E-mode metal-insulator-semiconductor (MIS) AlInN/GaN HEMT with an Au-T-gate has been investigated. The impacts of window-recess and deep-recess have been discussed, it was found that for dp=28 nm and wn=1.8 μm the threshold voltage achieves 0.7 V and the transconductance (Gm) peak value of 523 mS at Vgs=3.5 V. The drain current characteristic has been demonstrated

Approach for the Design of a Broadband Microwave Power Amplifier in Microstrip Technology for Mobile Communications Systems

This work presents a broadband power amplifier in S-band in microstrip technology. The proposed power amplifier is modeled with a single-stage architecture based on a field effect transistor ATF13786 of Agilent Technologies (hp)®. The used transistor has been polarized with transmission lines and it has been adapted with matching networks in the form of λ/4 transformers filters at the input and at the output. This amplifier has been studied and optimized using the Advanced Design System (ADS®) software. The simulation results of the output power and S parameters show excellent characteristics with a satisfactory gain greater than 10.9 dB, low reflections, a saturated output power of 16.4 dBm with a 1 dB compression point at an input power level of about 5 dBm, a maximum PAE of 25.3% and unconditional stability in the desired frequency band. The modeled amplifier can be integrated into mobile communications systems namely LTE mobile networks (2500 to 2690 MHz) and wireless networks using Wi-Fi protocol (2400 to 2485 MHz)

An ultra wideband antenna for Ku band applications

This paper presents a candidate ultra wideband antenna for Ku-band wireless communi- cations applications, analyzed and optimized by the finite element method (FEM). This three-dimensional modeling was realized and compared with published antennas for val- idate the performances of the proposed antenna. Its design is based on the insertion o fseveral symmetrical slots of different sizes on the ground plane of a mono-layer patch antenna to overcome the main limitation of the narrow bandwidth of patch antennas. The proposed antenna, made on an FR-4 epoxy mono-layer substrate with a defected ground plane (dielectric constant εr = 4,4, loss tangent tan δ = 0,02 and thickness hs = 1.6 mm). The simulated numerical results obtained are very satisfying; Bandwidth = 10.48 GHz from f1 = 9.34 GHz to f2 = 19.82 GHz, S11 = -34.17 dB, Voltage Stationary Wave Ratio VSWR = 1.04 , Gain = 6.27 dB

Reconfigurable ultra wideband to narrowband antenna for cognitive radio applications using PIN diode

Frequency reconfigurable antennas are very attractive for many wireless applications.They offer many advantages such as simplicity and compactness. In this electronicpaper, we propose a reconfigurable antenna operating in the S and C bands. Theproposed antenna uses a BAP65-02 RF diode to switch between the ultra widebandfrom 2.92 to 6.19 GHz to the narrowband from 2.92 to 3.93 GHz. The ultra widebandis obtained by a partial rectangular ground plane with a symmetrical rectangular slotand the narrowband is obtained by adding a parasitic element electrically connectedto the ground plane by the PIN diode when it is positively biased. This patch antennaoperates in the Federal Communications Commission band (FCC) and can be used forbiomedical applications such as radiometry imaging. The numerical simulation resultsbased on the finite element method and the finite integral method show a very goodagreement between them

Effect of a Mixture of Plants Extracts on Genomic DNA, Insulin Receptor, and Insulin Receptor Substrate-1 Genes in Alloxan-Induced Diabetic Male Rats.

This study was designed to study the effects of methanol-watery extracts mixture of five selective medicinal plants on genomic DNA, insulin receptor, and insulin receptor substrate-1 genes in alloxan-induced diabetic male rats. The molecular assays used in this study was DNA fragmentation test and polymerase chain reaction of insulin receptor and insulin receptor substrate-1. Phytochemical assays (thin layer chromatography (TLC) and antioxidant activity by ?- carotene spray) were carried out for characterization of methanol-watery extracts of each plants used (Trigonella faenum-graecum (fenugreek) seeds, Nigella sativa (black cumin) seeds, Zingiber officinale (ginger) rhizomes, Olea europeae (olive) leaves, and Fraxinus ssp.(ash) seeds). The results indicate presence of number of antioxidant bands with different retardation factors (Rf).   Molecular study of DNA showed fragmentation in both DNA extracted from WBC and renal cortex in diabetic group while treatment with mixture  of plants extracts significantly reduced DNA fragmentation in both DNA extracted from WBC and renal cortex in all treatment groups except treatment for 45 days which still had lyses level 5000 bp of DNA extracted from renal cortex. On the other hand, insulin receptor gene of diabetic and diabetic-treated groups for different periods (45, 60, 75 days) showed precense of one band (200 bp) compared with normal control which had two bands while insulin receptor substrate-1 has normal band (320 bp) in normal and treated groups. Keywords: alloxan, insulin receptor, insulin receptor substrate -1, antioxidant, DNA fragmentatio

Protective Effect of Plants Extracts Mixture on Sperm Abnormalities, Testicular and Epididymal Tissues in Diabetic Male Rats

Background: Diabetes has been associated with reproductive impairment in both men and women. About 90% of diabetic patients have disturbances in sexual function, including a decrease in libido, impotence and infertility. Attention has been paid to the search of effective drugs in the field of traditional medicine. Objective: The aim of the present study was to investigate the effect of diabetes mellitus type 2(T2DM)  on the sperm abnormalities, testicular and epididymal tissues of male rats. Also to evaluate the efficiency of the mixture of methanol-watery extracts composed of five medicinal plants (Trigonella faenum-graecum seeds, Nigella sativa seeds, Zingiber officinale rhizomes, Olea europeae leaves and Fraxinus ssp.seeds) in reducing harmful effect of DM on the percentage of sperm abnormalities, testicular and epididymal tissues. Methods: Twenty-four mature male rats were used in six groups (n=4), the first group kept as a control. The second group received alloxan (120 mg/ kg body weight i.p.) for 3 days to induction of T2DM while the third, fourth, and fifth groups were diabetic rats received the plants extracts mixture orally for 45, 60, 75 days, respectively after induction of T2DM. The sixth group received the plants extracts mixture for 60 days. By the end of the experiment, animals were sacrificed and the testis and epididymis were excised and sperm was collected for morphological abnormalities of the sperm shape. Also histopathological examination of the testes and epididymis were examined. Results: The sperm shape abnormalities significantly increased (p<0.05) in alloxan – induced diabetic rats compared with normal control group. Histopathological examination showed degenerative changes of both testes and epididymis in diabetic rats which include significant decrease (p<0.05) in both diameter of seminiferous tubules and their germinal epithelium heights and non-significant decrease (p>0.05) in both diameters of cauda epididymal tubules and height of epithelium of cauda epididymal  tubules. On the other hand, atrophied seminiferous tubules, atrophied spermatogenic cells and the lumen of semineferous tubules free from sperm was detected. Furthermore, expansion of interstitial space between seminiferous tubules were seen . In contrast , oral administration of the plants extracts mixture to the diabetic rats at three period of study 45, 60, 75 days, respectively statistically decreased (p<0.05) most sperms abnormalities compared with diabetic group and caused non-significant differences compared with control group besides enhancing the histological changes of both testes and epididymis. Conclusion: DM has negative effect in male testis and epidydimis of alloxan-induced rats and may contribute in reduction of fertility while the plants extracts mixture used in this study can reduce most degerenative changes occurred in testes and epidydimis in diabetic groups treated with the mixture of plants extracts. Therefore, plants extracts mixture can be effectively used by DM patients for therapeutic purpose. Key words: Alloxan- induced diabetes, Sperm Abnormalities, Histopathological Changes of testis and epididymis, rats

Thyroid Metabolic Hormones and its Correlation with BMI and Lipid Profile in Healthy People

Background:Thyroid hormone play an important role in basal lipid metabolism.It is well known that alteration in thyroid function can result in changes in the composition and in the transport of lipoprotein.This study aimed to study the effects of thyroid hormone on serum lipids and evaluted the correlation between thyroid hormone with Body Mass Index(BMI) and lipid profile of healthy people. Methods:Total of 56 healthy people(28 male:28 female) ,aged 30-60 years included in this study.About 5ml of fasting blood (8-12 h.) was collected from each individual.To determine serum Thyroid stimulating hormone (TSH), Triiodothyronine (T3) and Thyroxine (T4) and the quantitative sandwich enzyme immunoassay technique were used.Lipid profile were measured by an enzymatic colorimetric(GPO-POD) method. Results:The result of the present study showed that the levels of triglyceride was significantly higher (p< 0.05) in males than females ,while the levels of triiodothyronine was significantly higher(p< 0.05) in females than males of healthy people.Correlation analysis in healthy males showed positive correlation among BMI with lipid profile,while an inverse correlation between TSH and T4,also an inverse correlation between T3 and HDL .In healthy females there was positive correlation among T3 with BMI and WC,also between T4 and LDL ,while an inverse correlation between TSH and VLDL. Conclusions:Thyroid metabolic hormone especially T3 regulate the resting metabolic rate and the mild thyroid dysfunction was linked to significantly changes in body weight ,lipid profile and likely represents risk factor for healthy and obesity. Keywords:Thyroid metabolic hormone,lipid profile,BMI ,healthy peopl

Towards a full design of a super-wide band slotted antenna array using graphene material for future 6G applications

Sixth-generation (6G) wireless communication systems have been developed in response to the growing demand for higher data rates and ultra-high-speed communication. It is expected to emerge around the year 2030. In order to fulfill this need, the 6G wireless communication system will exploit the terahertz (THz) frequency spectrum (0.1–10 THz). In the same framework, the current study seeks to design and analyze various antenna and antenna array configurations across the whole THz range. Initially, by integrating graphene material into various patch and feedline combinations for a single antenna. The return loss, VSWR (Voltage Standing Wave Ratio), gain, and directivity of the antenna were the four key features that were analyzed. Furthermore, a parametric investigation of substrate thicknesses was carried out for three distinct materials: Rogers RT5880, silicon, and polymide. In order to increase the directivity and gain of the optimized graphene antenna, we used five different antenna array architectures (1*2, 1*4, 2*2, 2*4, and 4*2) in both serial and parallel configurations. Finally, a further enhancement of the structure—a sixteen-antenna array (2*8 array)—was implemented by doubling the arrays' structural dimensions to meet the requirements of the sixth generation of telecommunication systems in terms of gain and directivity

A New Frequency Reconfigurable Antenna Using Proximity Fed Technique for Wireless Applications

This electronic paper presents an innovative technology for efficient use of the radio spectrum. This new frequency reconfigurable rotatable antenna is intended for wireless applications such as WLAN, WiMAX and Bluetooth mobile applications. The working principle of this proposed work is to print square patches mounted on the same circular dielectric substrate feed by a proximity coupling to eliminate the noise signal transmission and problems related to interference. The three positions correspond to an operating frequency controlled by a bipolar step-by-step engine. An optimization of the structure using the FEM finite element method as well as a comparison with other structures recently realized are detailed in this paper. The final numerical simulation results are: WLAN 4.95-5.53 GHz (BW = 11%) Gain = 6.06 dBi, WiMAX 3.35-3.75 GHz (BW = 11.2%) Gain = 7.48 dBi and Bluetooth 2.3-2.51 GHz (BW = 8.7%) Gain = 17.78 dBi