In this paper, the resonance and radiation characteristics of rectangular microstrip patch printed on suspended and composite substrates are investigated theoretically. The analysis approach is based on the spectral-domain method of moments in conjunction with the stationary phase method. The complex resonant frequency of the microstrip antenna on suspended and composite substrates is studied with sinusoidal functions as basis functions, which show fast numerical convergence. Using a matrix representation of each layer, the far-field pattern of the suspended-composite configuration is efficiently determined by the (TM, TE) representation. The validity of the solution is tested by comparison of the computed results with experimental data. Finally, numerical results for the effects of suspended and composite substrates on the resonant frequency and half-power bandwidth are also presented.

This paper deals with robust direct power control of a grid-connected brushless doubly-fed induction generator(BDFIG). Using a nonlinear feedback linearization strategy, an attempt is made to improve the desired performances by controlling the generated stator active and reactive power in a linear and decoupled manner. Therefore, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability. Thus, an optimal operation of the BDFIG in sub-synchronous operation is obtained as well as the stator power flows with the possibility of keeping stator power factor at a unity. The proposed method is tested with the Matlab/Simulink software. Simulation results illustrate the performances and the feasibility of the designed control.

In this paper, an optimized ultra-low power phototransistor design based on gradual gate doping engineering is proposed. Using an analytical investigation and numerical simulation, an overall performance comparison of the proposed phototransistor design and conventional structure has been studied, in order to show the improved characteristics provided by the proposed design in terms of increased \(I_ON/I_OFF\) ratio and superior photoresponsivity capability. The results obtained from our analytical investigation are validated by comparison with the numerical simulations, thus establishing the accuracy of our analytical investigation. Moreover, the developed analytical models are used to optimize the proposed design using a genetic algorithm (GA) based-computation. The advantages offered by the proposed design suggest the possibility to overcome the most challenging problem with the power requirements of the optical interconnect: power consumption in the light emitter and in the receiver. In this context, the proposed phototransistor owing to the high responsivity requires less optical power from the light emitter to achieve an acceptable signal-to-noise ratio compared to the phototransistor with conventional design.

In this paper, the impact of the surface-textured front glass on the absorption of TiO 2 /glass thin-film ultraviolet (UV) photodetector is investigated, in order to achieve the dual role of increasing the scattering of UV-light as well as reducing the refracting UV-light in the glass. The efficient control of these phenomena may lead to more electric field confinement and UV-light trapping in TiO 2 absorber layer. Moreover, semianalytical modeling combined with particle swarm optimization is carried out for studying and enhancing the metal-semiconductor-metal photodetector optical and electrical performances. The results obtained from our semianalytical investigation are validated by comparison with the experimental data. It is found that the absorbance increases significantly by about 51% in optimized design over the planar structure, which is expected to improve the photodetector figures of merit. In this context, photodetector with optimized grooves texturization exhibits a 341% improvement, in terms of responsivity, in comparison with the planar structure and 275% improvement with respect to the textured device without optimization. The obtained results make the proposed design methodology a promising alternative for high-performance optoelectronic applications.