Volume 7, Issue 2, March 2011

Telepreneurship: The Art of Strategizing in the Telecommunication Industry [Full Text]

Izak Pierre Erasmus, Bradley Ryan Coyne and Assoc Prof. Jörgen Lindh

Abstract—
Recent research indicates innovation trends challenging corporate entrepreneurship formulation and its relation to a firm’s strat-egy. Acknowledging the significant research provided into strategy and entrepreneurship, this study aims to understand and further contribute in better aligning and strategically staging highly competitive telecommunication firms. With this, the authors propose a new adaptive frame-work coined the Teleprenuer framework which introduces a theoretical approach to help firms to exploit entrepreneurial practise in their inno-vation strategies, as well as strategic management into product portfolio management in relation to rapid technological innovation. Using grounded theory, the constructed Telepreneur framework serves both as an analytical as well as strategic tool used in the empirical data collection and analysis. Results from the empirical investigation into two leading South African telecommunication firms illustrates how the framework captures the strategic use of entrepreneurship in contextual and high rivalling industries and provides a new contribution to the science of entrepreneurship and strategic management enquiry.

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Characterization of Real Natural Modes Propagation on Mushroom-type High Impedance Surfaces
[Full Text]

Mohsen Fallah, Farrokh H. Kashani, Amir A. Heydari, Alireza mallahzade, and hosein M. Armaki

Abstract—
In this paper, propagation of real natural modes on sub-wavelength high impedance surfaces (HIS) composed of a dense grid (metallic patches or Jerusalem crosses) printed on a grounded dielectric slab with embedded vias (wired medium) are studied. Natural modes are composed of proper real forward and backward surface waves, improper real forward and backward waves, and proper and improper forward and backward complex leaky waves.This paper focused on analytical characterization of real type natural modes on above mentioned HISs. The stopbands of proper real surface modes for electromagnetic band-gap (EBG) applications of HIS are studied by dispersion and surface impedance diagrams. The EBG bands obtained by dispersion diagrams are verified by surface impedance diagrams. In dielectric slab with vias, the effects of spatial dispersion (SD) on homogenization model of the structure and additional boundary conditions (ABC) are included within the limits of homogenization. Moreover, the results that are obtained by analytical models are verified by numerical full wave HFSS simulations.

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A High performance Mode Coupler for Tracking Feed Antennas
[Full Text]

S. H. Mohseni Armaki, F. H. Kashani, J. Rashed Mohassel and M. Fallah

Abstract—
This paper describes a compact TE21 mode coupler that enhances the tracking performance and operating bandwidth of earth station antennas. The mode coupler is designed by a side-wall slot coupling mechanism which utilizes the overmoded circular waveguide that provide the sum and difference channels, respectively, to achive monopulse tracking. Optimum length of slot in the TE21 mode coupler improves the tracking mode coupling efficiency. A
prototype was simulated, manufactured and measured. The measured results demonstrate excellent agreement with simulated results. Based on simulated and measured data, 0.3dB transmission loss is achieved over a 13% bandwidth in a tracking mode of the feed system.

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Compact Microstrip Step Discontinuity Compensation Using Defected Microstrip Structure
[Full Text]

Omid Hoseini Izadi and Mohammad Khalaj-Amirhosseini

Abstract—
A novel compensation method for microstrip step-in-width discontinuity using Defected Micristrip Structure (DMS) is proposed. The presented method compensates for junction reactance in a much smaller length than conventional tapering technique. This capability is of great importance in MIC and MMIC technology. Heavy simulations are carried out to obtain useful closed-form expressions for DMS dimensions. In order to validate the obtained design expression and simulation results, a prototype circuit was designed and fabricated using the derived expression. The measurement results are in good agreement with simulation results.

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Matlab Based Teaching Tools for Microstrip Patch Antenna Design
[Full Text]

K.O Odeyemi, D.O Akande and E.O Ogunti

Abstract-
This paper provides details on how to investigate a new method of teaching microstrip patch antenna design for undergraduate students by
using MATLAB in-conjunction with one of the electromagnetic software packages called SONNET that can be called from MATLAB program. This is
achieved by designing a friendly graphical user interface (GUI) for microstrip patch antennas through which antenna parameters and radiation pattern can
be determined and also directly called Sonnet for electromagnetic simulation of the antenna.

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Optimization of Wideband Antenna Using Microstrip Patch: An impact on Wireless Communications
[Full Text]

Samiran Pramanik, Taniya Guha, Indrani Nath and Nirmalendu Bikas Sinha

Abstract—I
n this paper authors explore wideband antenna using microstrip patch having a 2:1 VSWR with impedance bandwidth of 34% covering the 5.2/5.8 GHz WLAN, HIPERLAN2, and HiSWANa communication bands. The large bandwidth is obtained by adding a mirror image of G shaped microstrip patch directly over the substrate. The antenna occupies an overall dimension of 20 mm × 40 mm × 1.055 mm, when printed on a substrate of dielectric
constant 4.4 F/m. It exhibits good characteristics and moderate gain in the entire operating band. Details of the design along with experimental and simulation results are presented and discussed. Finally this paper addresses the current question regarding the optimization of wideband antenna on wireless communication.

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MATLAB Implementation of Multiuser Code Division Multiple Access
[Full Text]

A. A. Patel and A. D. Patel

Abstract—
Some of the difficulties in the study of new generation wireless mobile systems are lack of practical implementation for various strategies like, multiuser code division multiple accesses, assigning radio resources using DSSS, use of orthogonal codes etc. In this paper we are going to discuss some of the above stated problems with their implementation issues. CDMA is a scheme by which multiple users are assigned radio resources using DS-SS
techniques. Although all users are transmitting in the same RF band, individual users are separated from each other via the use of orthogonal codes. Capacity is defined as the total number of simultaneous users the system can support, and quality is defined as the perceived condition of a radio link assigned to a particular user. We have use MATLAB as a simulation tool and result shows how multi-user CDMA performs under certain circumstances.

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Design of Modified Sierpinski Carpet Fractal Antenna [Full Text]

Rajneesh Chawhan, Dr. P. K. Singhal and Dr. C. Das. Gupta

Abstract
This paper describes the design and fabrication of modified Sierpinski carpet fractal antenna. The analysis took place between ranges of 0.5GHz to 3GHz. The fabricated modified Sierpinski carpet fractal antenna proves that it is capaple to create multiband frequencies. There are five resonant frequencies appeared at 0.89 GHz, 1.91 GHz, 2.17 GHz, 2.72 GHz and 3.0 GHz.