Darwish Abd el aziz Mohamed

• Professor Doctor
• Professor at Faculty of engineering / AAST

In this paper, a novel wide band monopole antenna is designed to operate at the millimetric wave (mmW) frequency band with impedance bandwidth of 26-70 GHz for 5G wireless communication applications. First of all a conventional antenna is designed on full ground then it designed on partial ground with size 5mm x 10mm but both designs didn't achieve...

Orthogonal frequency division multiplexing (OFDM) can be combined with antenna arrays to increase a system competence on time variant with the frequency selective channels which cause a multiple input multiple output (MIMO) composition. The main disadvantage of MIMO-OFDM is its high peak average power ratio (PAPR). In this paper, a hybrid technique...

This paper presents a new, efficient data detection for coherent signals in the uplink direction of Long Term Evolution (LTE) system for multiuser in multipath environment through adaptive processing of antenna arrays at the base station. The proposed algorithm at the receiver depends on a robust beamforming based Direction of Arrival (DOA) estimat...

This paper presents a new, efficient data detection for coherent signals in the uplink direction of Long Term Evolution (LTE) system for multiuser in multipath environment through adaptive processing of antenna arrays at the base station. The proposed algorithm at the receiver depends on a robust beamforming based Direction of Arrival (DOA) estimat...

In this article, the performance of compact planar wearable antenna 4.1 × 4.1 cm2 mounted on different phantoms and human body fed by microstrip line is designed to operate in ultra-wide band applications. The proposed antenna consists of a circular patch with notch-cut and U-shaped slot on the upper side of the substrate and finite ground plane wi...

A robust blind beamforming algorithm is proposed for Long Term Evolution (LTE) system in the uplink direction using a Uniform Linear Array (ULA) at the base station (eNodeB) in the multipath environment. There is no information about the incoming signals, so a robust estimation of the Direction of Arrival (DOA) of the received signals is performed...

In this paper, four–elements multiple-input– multiple-output (MIMO) antenna is presented for ultrawideband (UWB) applications. The proposed UWB MIMO array has dimensions of 40 × 40 mm2 is printed on FR4 epoxy substrate with the dielectric constant of 4.4 and a thickness of 1.5 mm. Simulation and Experimental results of verify the improved impedance...

Modern satellite, wireless communications, and radar systems often demand the wideband performance for multi-channel and multi-function operation. Recent technologies enable electronic and RF circuits in radar and communication devices to be miniaturized and become physically smaller in size. Antenna design has been one of the key limiting constrai...

In this paper adaptive BeamForming (BF) is considered for a smart antenna system in the Long Term Evolution (LTE) uplink receiver (4G mobile communication system) by using a Modified Robust Variable Step Size-Least Mean Square (MRVSS-LMS) algorithm with pilot channel estimation and equalizer in the receiver. The algorithm is presented for Single Ca...

Microstrip antennas have been developed for various applications such as broadband High speed wireless communication systems and automotive radar systems. They are more advantageous than other millimeter-wave antennas at the viewpoints of low profile and low cost. As the target radar cross section (RCS) continuously decreases, the need for high gai...

Control and manipulation of electromagnetic waves is at the heart of many industries from wireless communication, Internet and optical data storage to imaging and displays. Progress in these technologies places challenging demands on material properties and therefore structured electromagnetic materials. Metamaterials are a special class of structu...

Beamforming is a signal processing technique that has the ability to direct the main beam toward signal-of-interest and the null toward signal-of-not-interest without moving antenna array. This technique is achieved by using algorithms which change the amplitude and phase of array pattern continuously. This paper presents hybrid algorithm that is a...

Metamaterials represent a new paradigm in electromagnetic science and technology. They have already leaded to many unprecedented microwave applications, which may be classified in three categories: guided-wave, radiated-wave and refracted-wave applications. Radiated-wave applications cover several types of novel antennas and reflectors, which may b...

Time Adaptive Processing (STAP) applied on signal received from different configurations of real elements using D3LS (Direct Data Domain Least Squares). We will discuss the impact of each typical element-missing on the performance of this approach and the precision of the estimated strength of the SOI. We are interested in five different antenna co...

In this article, a new elliptical slotted arrowhead defected ground structure (DGS) is proposed for designing a multilayer low pass filter (LPF) with wide rejection band and low insertion loss in the stop-band. The prototype LPF consists of three elliptical slotted arrowhead DGS cells etched in the ground plane with a compensated capacitor on the t...

In this article, a new compact defected ground structure (DGS) low pass filter (LPF) with wide rejection band, low insertion loss in the stopband, and sharp transition from passband to stopband is proposed. The prototype LPF is composed of three repetitive DGS elements with open stubs to act as a compensated capacitance. Each single DGS element con...

Space Time Adaptive Processing (STAP) applied on signals received from different configurations of real elements using D 3 LS (Direct Data Domain Least Squares) in order to estimate the direction of each incoming signal. The algorithm deals with the actual desired signals as interferences and we can easily detect their directions. We use a preproce...

In this paper, Space Time Adaptive Processing (STAP) applied on wideband signals from uniformly spaced real elements using Direct Data Domain Least Squares (D 3 LS). Two antenna configurations are used: an array of dipole antenna (narrowband antenna) and an array of patch antenna (wideband antenna). A frequency transformation technique is used only...

In this paper, STAP applied on signals from planar array of real elements using D³LS. The estimation of complex amplitude of Signal of Interest (SOI) will be difficult due to the strong mutual coupling between real elements. We have to eliminate the mutual coupling that exists between the antenna elements by using the transformation matr...

A Direct Data Domain Least Squares (D3LS) approach is developed for multiple target detection in Space Time Adaptive Processing (STAP) and is applied on signal received from different configurations of real elements. We are interested in three different kinds of antenna configuration which are non-uniformly spaced linear array, semicircular array a...

This paper presents a Bow-Tie slot antenna for wrist applications used in the long and short range tracking systems. The slot introduced into the patch as well as using the proximity-coupling technique; enhance the antenna bandwidth and thus overcome the limitation of the basic microstrip antenna while still maintaining the compactness of the anten...

In this paper, STAP applied on signal from uniformly spaced real elements using D³LS. The mutual coupling between real elements will affect on the estimation of complex amplitude of Signal of Interest (SOI). It is necessary to use a transformation matrix to compensate for the strong mutual coupling that exists between the antenna element...

In this paper, Space Time Adaptive Processing (STAP) applied on signal received from different configurations of real elements using D³LS. We are interested in three different kinds of antenna configuration which are non-uniformly spaced linear array, semicircular array and sinusoidal spaced array. The mutual coupling between real elemen...

In the literature, the bounds of the peak to average power ratio (PAPR) are generalized to both complex-valued and real-valued orthogonal frequency division multiplexing (OFDM) signals. In fact, these bounds are accurately bounding the PAPR distribution of complex-valued OFDM signals only. In this paper, we derive accurate PAPR bounds of real-value...

In this paper, an investigation of the performance of the wavelet transform and wavelet packet based multicarrier CDMA communications in Rayleigh fading channel is presented for different wavelet families. Replacing the Fourier based complex exponential carriers of MC-CDMA with orthonormal wavelets packets in the application of discrete wavelet pac...

A major drawback of orthogonal frequency-division multiplexing (OFDM) signals is their high peak-to-average power ratio (PAPR), which causes serious degradation in performance when a nonlinear power amplifier (PA) is used. Companding transform (CT) is a well-known method to reduce PAPR without restrictions on system parameters such as number of sub...

A major drawback of orthogonal frequency-division multiplexing (OFDM) signals is their high peak-to-average power ratio (PAPR), which causes serious degradation in performance when a nonlinear power amplifier (PA) is used. Companding transform is a well-known method to reduce PAPR without restrictions on system parameters such as number of subcarri...

In this paper several configurations of circular microstrip antenna fed by coaxial lines are designed to achieve wide bandwidth. An extra dielectric substrate added on top of a conventional circular patch and an air gap added are also designed. A large bandwidth was achieved by all those designs. The analysis was carried out by using the ready made...

The linearly constrained minimum variance (LCMV) algorithm fails to capture the signal if coherent copies (multipath signals) impinge on the array at the same time with the signal. The constant modulus algorithm (CMA) and the multi-modulus algorithm (MMA) techniques solved this problem with the disadvantage of more complicated behavior and the viol...

A stacked microstrip antenna with C-type feed is designed in order to enhance the bandwidth. The effect of the various parameters, such as the rotation feed angle (thetas), the variations of relative permittivity of parasitic patch (epsiv_r2), the distance of the feed point from the center (r), and the separation between two stacked patch...

In this paper, we introduce the margin adaptation problem for both single and multiuser OFDM systems and illustrate its optimal solution. Due to the high complexity and long execution time of this solution, simple solutions of this problem have been studied by applying algorithms having lesser complexities and hence reduced the execution time of th...

Signal clipping and μ-law companding have been suggested as simple and effective peak-to- average power ratio (PAPR) reduction schemes for orthogonal frequency-division multiplexing (OFDM). This paper, addresses the problem of PAPR and the relation between it and the number of subcarriers, and analyzes clipped and companded M-ary phase-shift keying...

MC-CDMA inherits the interference rejection capability of CDMA, and the potential of mitigating multipath propagation effects of orthogonal frequency division multiplexing (OFDM). MC-CDMA with its frequency diversity is an attractive modulation scheme for multi-user high data rate wireless communication system. However on OFDM and MC- CDMA sub-chan...

Signal clipping and conventional μ-law companding have been suggested as simple and effective peak-to-average power ratio (PAPR) reduction schemes for orthogonal frequency division multiplexing (OFDM) that can be applied without restriction on the number of subcarriers, frame format, and constellation type. This paper, addresses the problem of PAPR...

In this paper a probe fed printed bow-tie antenna with different configurations are designed to achieve a wide impedance bandwidth. A double-sided printed triangular bow-tie antenna with a pair of slits is designed and a wide impedance bandwidth required for Ultra Wide Band (UWB) applications is achieved .The analysis was carried out by using the f...

In this paper, we address the antenna selection problem in spatially correlated Multiple-Input Multiple Output (MIMO) channels. To reduce the severe performance degradation of the traditional antenna selection scheme in correlated channels, we propose to embed Discrete Wavelet Transform (DWT) operations in the RF chains. The resulting system shows...

Summary form only given. This paper proposes a framework for the analysis of joint antenna selection (JAS) strategies at both link ends. Two selection criteria which exploit the exact and statistical channel knowledge are presented. We demonstrate through extensive simulations that joint antenna selection is a promising antenna selection strategy t...

This paper studies the performance of existing receive antenna selection algorithms in spatially correlated fading MIMO channels. The antenna subset is selected based on maximizing the channel capacity. First the most recently proposed algorithms, which are dedicated to i.i.d channel, are revisited and investigated. Then, we apply these algorithms...

In this paper an equilateral triangular slot antenna and microstrip antenna that were fed by coplanar waveguide (CPW) are designed to achieve wide impedance bandwidth. A probe fed triangular microstrip antenna with a pair of slits and a probe fed triangular microstrip antenna with four triangular parasitic elements are also designed and wide impeda...

The constant modulus array (CMARY) is a blind adaptive beamformer, which is capable of recovering a narrowband signal that is received along with other cochannel signals without using a pilot or training signal. It is based on the constant modulus algorithm (CMA) The CMARY typically captures the signal that has the greatest power among the cochanne...

Hallen's integral equation with continuous resistive loading is used to design a broadband monopole antenna. The resistive profile is different from that of the well known Wu-King profile and results in a higher efficiency compared to the latter. An optimization function for determining the optimal continuous resistive load of the monopole antenna...

The log - periodic normal mode helical antenna with ground reflector is investigated as a new type of antenna, which provides wide bandwidth, broad beam-width, and high gain. This antenna has smaller transverse dimensions than a log - periodic dipole antenna and a log - periodic loop antenna. Several geometries with different parameters are analyze...

In this paper, a printed elliptical slot antenna fed by different tapered microstrip line with U-shaped and Circular ring-shaped tuning stub is proposed for ultra-wideband (UWB) applications. The tapering aids in minimizing the reflection at the interface between the microstrip feed line and the tuning stub. Introduced is a new tapering profile tha...

The smart antenna systems combine antenna arrays with digital signal processing (DSP) algorithms. In a smart antenna system a specialized signal processor computes the direction of arrival (DOA) of a user and also adds the strength of the signals from each antenna element together to form a beam towards the direction as computed by DOA. If addition...