Abstract: In modern wireless communication systems and increasing of other wireless applications, wider bandwidth, multiband and low profile antennas are in great demand for both commercial and military applications. This has initiated antenna research in various directions; one of them is using fractal shaped antenna elements. Traditionally, each antenna operates at a single or dual frequency bands, where different antenna is needed for different applications. This will cause a limited space and place problem. In order to overcome this problem, multiband antenna can be used where a single antenna can operate at many frequency bands. One technique to construct a multiband antenna is by applying fractal shape into antenna geometry. This project presents the Sierpinski carpet patch antenna where this famous shape, the antenna behaviors are investigated. In addition to the theoretical design procedure, numerical simulation was performed using software (CST) to obtain design parameters such as size of patch and feeding location. The antennas have been analyzed and designed by using the software CST Microwave Studio Suite.

Abstract: In this paper, a new wideband antenna with meandered feed line is presented which can be used in radio frequency (RF) energy harvesting. The proposed antenna is designed on 36 by 56.5 mm² FR4 board with thickness of 1.6 mm and dielectric permittivity constant and tangent loss of 4.3 and 0.025, respectively. It consists of circular disc antenna, two ring patches and three rectangular slots on the ground plane as well as a meandered feed line. Although any RF signal could be useful from energy harvesting point of view, the proposed antenna shows a wideband frequency range from 1.59 to 6.62 GHz and 7.44 GHz to 8 GHz in reference to -10dB return loss or better for wideband applications.

Abstract: Modern communications systems will have to integrate multiple radio technologies to support a large number of wireless standards (WLAN, WPAN…). This system should operate with third generation (3G) air interface standards, where non constant envelope modulation formats (MQAM, OFDM…) are required. The amplification of a modulated signal with large variation of envelope introduces distortions when the input-output characteristic is nonlinear. These distortions are particularly important when the power amplifier (PA) has non-linear memory effects with a wideband signal. The technique proposed in this paper aims to fight against this phenomenon by optimizing the method developed in the laboratory for a real-time implementation. This technique is able to provide exactly the reverse characteristics of a PA modeled by a Hammerstein model in base band. Its principle is to find the largest real root of a polynomial related to the analytical model of the PA and to the input signal to be amplified to calculate a pre-distorted signal. To reduce significantly the computation time, an implementation by the LUT method is proposed. This method uses two pre-distortion principles and can be implemented on a FPGA board with table bases method known for simplicity including in the same way the correction of the memory effect.

Abstract: This paper studies a new signal transmission scheme founded on duty-cycle modulation. The proposed signal transmission system consists of a low cost duty-cycle modulation circuit, a transmission line model and a linear demodulator. The study of the signal transmission system is conducted using analytical developments and virtual simulation models. Then, the results obtained under a variety of modulating waveforms including standard signals and arbitrary waveforms, show the high quality of the proposed duty-cycle modulation scheme for signal transmission systems.

Abstract: The effect of elastic strain of moderate magnitude using high doped silicon substrate can change the conductivity of the substrate. The commonly used metal (strain) gage has a magnitude factor of between 2 ÷ 4 while high doped silicon (strain) gage factor magnitude is between 150 ÷ 200, thus improving the substrate sensitivity considerably. Using those physical attributes allow us to create a MOEMS sensor resolving accuracy issues and saving space in any future MOEMS device design. Those devices will be able to measure any mechanical movement connected to the high doped silicon substrate by converting the physical strain created from the movement stress to current/voltage change in the substrate device. The simplicity of the device is that the device could measure movement without any need to implement an outer sensor to it. By measuring the device's strain change it would "feel" the movement and convert it to an analog value, thus creating a strain gage built in the MOEMS device surface.

Abstract: The demand of mobile user is ever increasing in this world of digital systems. Consumers demand more from their technology. Whether it is a television, cellular phone, Washing machine or refrigerator, the latest technology purchase must have new features. With the advent of the Internet, the most-wanted feature is better, faster access to information. The time not far away when access to all necessary information and the power of a personal computer, sits in the palm of one’s hand. To support such a powerful system, we need pervasive, high-speed wireless connectivity. The drawbacks of the current mobile communication technology have led the researchers to come up with more advanced and efficient technologies. 4G mobile technology is the outcome in this direction. 4G is the next generation of wireless networks that will totally replace existing 3G networks. It is supposed to provide its customers with better speed and all IP based multimedia services. In the present scenario existing technologies are capable of performing functions like broadband data access, supporting voice traffic using voice over IP (VoIP), in mobile environment etc., but there is a great requirement of integrating all such technologies into a single combined system. 4G promises a solution to this problem by seamlessly integrating the terminals, networks and applications. This paper presents an overall study of the 4G systems, architecture, standard, benefits, challenges in implementation, design for the LTE and WiMAX technologies, Security issues and future scope of 4G technologies.

Abstract: A new multiplier-divider circuit using a single Current Differencing Buffered Amplifier (CDBA) and only six MOSFETs has been presented. The proposed circuit has the advantage of simultaneously realizing a multiplier and divider without changing the circuit topology. The basic functions of the proposed circuit have been verified through PSPICE simulations using a CMOS CDBA and NMOS transistors with process parameters of 0.35 µm CMOS technology and some application results of the proposed cell in various modes of operation have been included.

Abstract: Many small size enterprises, other organisms and rural people mostly in underdeveloped countries do not have an easy access to the grid, and are then in the need of a decentralised electric sources which appear as crucial in some cases specially when feeding rural hospitals, or serve for pumping drinkable or irrigation water. Electric Solar Generators Technologies could then efficiently come to rescue. This article focuses on the analysis of keys factors for a design, and an implementation of such a PV Solar Generator. We have in that aim proceeded to a study of the state of art in that domain of Solar Electric Generators, which offered keys parameters of each component of a safe easy maintainable feeding solar system, and lead us to the design notably owing to the software PVSyst, to the implementation of and the experiments of a domestic flat PV solar generator. Results are constituted by the designed schematics, tables and curves of simulated and experiments electric quantities like the maximum delivered powers, and the efficiencies. The article reported an example of a complete PV system installed, and instrumented for data logging. That system included a battery and an inverter to power real loads. The system design parameters comprised the size of the PV array, the battery size, and the power rating of the inverter, as well as the power delivered to the loads. The data logged have been used to evaluate the designed system and to make assessments on how the system design could be improved so that systems of this type could serve the local needs most economically.

Abstract: Temperature continues to be an issue in the reliability of high power laser diodes. Any effort, therefore, made to understand the dynamics of temperature on the performance of laser diodes is important. This is because it serves as a catalyst for the generation of nonradiative recombination centers, which ultimately kills laser diodes. In this paper, the convolution of simulation results was done to compare it with experimental results, which revealed more details that hitherto, could not have been captured by experiments alone. The inability of experiments to capture these details is due to the limited spatial resolution of the charged-coupled device (CCD) camera, which is approximately 30 μm much larger than the thickness of the quantum well active region used in the experiment. The convolution results showed a further smile-shaped profile within the four groups of array emitters, which in the experimental results, were considered as one emitter due to the limited spatial resolution of the CCD camera. The use of convolution to determine more details was investigated, due to the dominant effect of temperature found across the output power distribution of high power semiconductor laser diode bars.

Abstract: This work includes Zeta voltage converter controller design and implementation. The mathematical model of the zeta converter circuit operating in the continuous conduction mode in state-space form is presented. Fuzzy Logic controller and hybrid Fuzzy Logic controller/ particle swarm optimization techniques are used to designed controller. Analysis and comparison between simulation and practical responses of open loop, close loop fuzzy logic controller and hybrid fuzzy logic/particle swarm optimization controller results are performed for different, working conditions such as sudden changes in the load resistance and reference voltages. The results show that there are significant improvement in the results for the proposed hybrid FLC/PSO control technique.