Rashid Saleem

EMPIRICAL MINIATURIZATION ANALYSIS OF INVERSE PARABOLIC STEP SEQUENCE BASED UWB ANTENNAS

In this paper we develop an empirical approach to the design of Ultra Wideband (UWB) antennas employing the Inverse Parabolic Step Sequence (IPSS). The relationships developed can be used to miniaturize the antenna and achieve a good impedance match over the UWB bandwidth. The overall aim of this process is to give a good starting point for detailed numerical optimizations. We will illustrate the use of these formulae in three difierent designs of IPSS- based antennas. A low loss duroid substrate of loss tangent, tan-, 0.0009, low relative permittivity 2.2 and thickness 1.575mm is used to simulate these planar monopole antennas in Ansoft High Frequency Structure Simulator (HFSS).

Channel Estimation Based in Comb-Type Pilots Arrangement for OFDM System over Time Varying Channel

Orthogonal Frequency Division Multiplexing (OFDM) has been recently applied widely in wireless communication systems, due to its high data rate, transmission capability with high bandwidth, efficiency and its robustness to multipath delay .Channel estimation is an essential problem in OFDM system. Pilot-aided channel estimation has been used; a good choice of the pilot pattern should match the channel behavior both in time and frequency domains. We explored comb pilot arrangements. The advantage for comb type pilots arrangement in channel estimation is the ability to track the variation of the channel caused by doppler frequency, it is observed that the doppler effect can be reduced, and so this will increase the system mobility. Kalman and Least Square (LS) estimators have been proposed to estimate the Channel Frequency Response (CFR) at the pilots location, then CFR at data sub channels are obtained by mean of interpolation between estimates at pilot locations. Different types of interpolations have been used such as; low pass interpolation; spline cubic interpolation and linear interpolation. Kalman estimation has better performance than LS estimation. The estimators perform about the same for SNR lower than 10 dB. The performances of all schemes have been compared by finding Bit Error Rate (BER), where BPSK modulation scheme was used.

A Miniaturized Flexible Frequency Selective Surface for X-Band Applications

In this paper, a novel and miniaturized band-stop frequency selective surface (FSS) is presented. This FSS provides effective shielding in X-band, with attenuation of at least 56 dB. The proposed FSS provides 3-dB fractional bandwidth of 48% which is necessary to cover X-band. Moreover, the proposed design is polarization independent as it provides a stable frequency response at normal and oblique angles of incidences for both perpendicular TE and parallel TM wave modes. The copolarized and cross-polarized scattering parameter S21 is analyzed at the selected band-stop/notch frequencies. More importantly, the proposed FSS is suitable for conformal applications and hence finds wider employability. A prototype of the proposed FSS is fabricated and tested. The measured results are in good agreement with the simulated results.

Kalman filter channel estimation based on Comb-type pilots for OFDM system in time and frequency -selective fading environments

Kalman-filter method have been used for the estimation of time-frequency-selective fading channels in OFDM systems, the estimation is based on Comb-type pilot frequencies arrangement, the channel coefficients that belong to the pilot subcarriers are estimated. Then these estimates are interpolated using different types of interpolations like; Low pass interpolation, Spline cubic interpolation or Linear interpolation. The performances of all schemes have been compared by finding Bit Error Rate where BPSK modulation scheme was used.

Using Reduced Interference Distribution to Analyze Abnormal Cardiac Signal

Using Reduced Interference Distribution to Analyze Abnormal Cardiac Signal Due to the non-stationary, multicomponent nature of biomedical signals, the use of time-frequency analysis can be inevitable for these signals. The choice and selection of the proper Time-Frequency Distribution (TFD) that can reveal the exact multicomponent structure of biological signals is vital in many applications, including the diagnosis of medical abnormalities. In this paper, the instantaneous frequency techniques using two distribution functions are applied for analysis of biological signals. These distributions are the Wigner-Ville Distribution and the Bessel Distribution. The simulation performed on normaland abnormal cardiac signals show that the Bessel Distribution can clearly detect the QRS complexes. However, Wigner-Ville Distribution was able to detect the QRS complexes in the normal signa, but fails to detect these complexes in the abnormal cardiac signal.

Inverse parabolic step sequence ultra wideband antenna

A novel ultra wideband (UWB) monopole antenna is proposed in this paper with 3–16 GHz bandwidth and a voltage standing wave ratio VSWR of £ 1.83. It is designed on a planar Duroid substrate of relative permittivity er = 2.2 and area of 27 × 29mm2. Fed by a rectangular Coplanar Waveguide (CPW), it has a non-rectangular sequence of steps formed by an alternate combination of inverse parabolic functions. The antenna is simulated using Ansoft HFSSTM and the results show that it has good performance with respect to bandwidth and radiation pattern.

A KINETIC STUDY OF RUBAZOIC ACID FORMATION DERIVED FROM 4-AMINO-1(4-SULPHOPHENYL) 3-METHYL-2-PYRAZOLIN-5-ONE.

Ghulam Hussain 1 , Shakeel Ahmad Khan 2* , Waqar Ahmad 2 , Makshoof Athar 1 and Rashid Saleem 3 . 1. Institute of Chemistry, University of the Punjab, Lahore 54590, Pakistan. 2. Department of Chemistry, University of Management and Technology Lahore-54000, Pakistan. 3. Department of Chemistry, GC University, Kachehry Road, Lahore 54000, Pakistan. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

An FSS-Based Nonplanar Quad-Element UWB-MIMO Antenna System

In this letter, a low-profile, miniaturized four-element ultrawideband (UWB) antenna for four-port multiple-input–multiple-output (MIMO) configuration is proposed. The MIMO antenna elements are organized in a cuboidal geometry around a polystyrene block. An inverted L-shaped structure provides decoupling among the antenna elements. This structure is frequency-selective-surface-based and has slotted Y-shapes etched in it. In addition to that, a square spiral parasitic structure improves input impedance matching over the desired frequency band. Antenna elements are realized on low-profile FR-4 substrate having compact dimensions of 32 × 36 × 1.5 mm

Impact of Collection Efficiency on the Optical Responsivity of Lattice Matched InP/InGaAs Heterojunction Phototransistors

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Miniature inverse parabolic step sequence damped sinusoid antenna for DS-UWB

. The proposed three-dimensional (3-D) UWB-MIMO system achieves good impedance matching and an effective isolation of 20 dB among antenna elements in most of the band. The reported configuration is suitable for nonplanar/3-D system-in-package applications where a planar arrangement of four elements is not possible due to size limitations.