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Effect of Slot on Ground Plane in Enhancing
the Impedance Bandwidth of Modified Rectangular Microstrip Antenna and Its Array
-- S L Mallikarjun, P M Hadalgi, S K Satnoor and P V Hunagund
Compact broadband microstrip antennas have recently received much attention due to the increasing
demand for extremely small antennas covering a wide operation bandwidth for many radar and satellite
communication applications. This paper reports a method to enhance the impedance bandwidth of a rectangular
microstrip antenna by suitably modifying its geometry in the form of plus shape. The experimental results show that
there is an improvement of 12.27% impedance bandwidth, when compared to conventional microstrip
antenna. Further, after incorporating the optimum slot in the ground plane, the impedance bandwidth increases
to 29.4%. This impedance bandwidth becomes 39.5% when two-element array is constructed. This
enhancement is achieved at X-band frequency without much change in the radiation pattern. The wideband operation of
the proposed antennas may find applications in modern communication systems.
© 2009 IUP. All Rights Reserved.
Radiation from Tapered Nylon Rod Antennas:
A Computational Study
-- J Subramanyam and M V S Prasad
Extensive studies on the radiation patterns of Polystyrene, Perspex and Teflon dielectric rod antennas
are reported in the existing literature. In the present work, computational studies on radiation patterns of
tapered Nylon rod antennas are carried out with the objective of finding the optimum dimensions of the antennas.
The length of the Nylon rod is varied from
2l0 to 6l0. For each of these lengths, the radiation patterns of Nylon
rod antennas with different taper angles are computed. The variation of Half Power Beam Width (HPBW)
from Side Lobe Level (SLL), with length and taper angle, shows a
2.5° taper over a length of
6l0 as an optimum choice. The principal plane and 3D patterns are presented for this optimum choice of dimensions.
© 2009 IUP. All Rights Reserved.
Measurement of Dielectric Constant
and Loss Tangent of Fabric Materials
Suitable for Wearable Antennas
-- S Sankaralingam, Bhaskar Gupta and S Raghavan
An approach to the measurement of dielectric constant and loss tangent of fabric substrate materials, used
for the development of wearable antennas, is presented in this paper. This technique is based on the parallel
plate method of measuring capacitance, and focuses on the use of RF impedance/material analyzer. The
permittivity of the material under study is obtained by its relationship with the capacitance. The insertion loss is
measured by the material analyzer, and therefrom, the loss tangent is determined. The validity of the method is
demonstrated for a well-characterized substrate material such as Teflon. The technique is then applied to the insulating
fabric substrates.
© 2009 IUP. All Rights Reserved.
Space Vector PWM for a Six-Phase VSI Supplying a
Six-Phase and a Three-Phase Series-Connected Machine
-- Atif Iqbal, Mohd. Ayyub and M Arif Khan
A six-phase two-motor drive system with series connection of stator windings of a six-phase and a
three-phase machine and decoupled dynamic control, has been introduced recently. The electric power to the
two-motor drive system is supplied from a single six-phase Voltage Source Inverter (VSI) and controlled
using vector control scheme. If current control is to be implemented in the rotating reference frame, the Pulse
Width Modulation (PWM) method for the six-phase VSI is required to generate the required voltages. This
paper proposes a scheme to generate inverter output voltages using space vector PWM in such a way that
independent control of two series-connected machines is achieved with a minimum interaction between the two
machines. The method generates output voltages that contain only two low-frequency fundamentals at the
operating frequencies required by the two machines. The application area of the proposed configuration is
identified. The required six-phase inverter rating under steady state is obtained analytically and the concept is verified
by simulation.
© 2009 IUP. All Rights Reserved.
Fuzzy Logic-Based Controller
for Three Area Power System
-- H D Mathur, H V Manjunath and R C Bansal
The paper presents a fuzzy application to the area of Load Frequency Control (LFC) using fuzzy
logic-based integral controller. The study is designed for a three area interconnected power system with generation
rate constraint. Simulation results of the proposed fuzzy controller are presented. It is shown that the
proposed controller can generate good dynamic response, following a step load change. The robustness of the
proposed controller is achieved by analyzing the system response with varying system parameters.
© 2009 IUP. All Rights Reserved.
Load Flow Analysis for Unbalanced Radial
Distribution Systems: A Comparison of Different Practical Methods
-- Sivkumar Mishra and Debapriya Das
Power distribution systems fall in the category of ill-conditioned power systems due to their various
special features which make them different to analyze, when compared to transmission systems. Moreover,
distribution systems are inherently unbalanced. Special three-phase load flow methods, known as Unbalanced
Distribution System Load Flow (UDSLF) methods, are needed to exploit the special topological properties, as well as
to overcome the difficulties arising out of the ill-conditioned nature of the distribution systems. The
modeling aspect of the unbalanced distribution system has been discussed. Three established methods suitable
for UDSLF have been presented in this paper in some detail, with their respective algorithms developed.
The performances of these methods are compared, considering multiphase practical test distribution systems.
© 2009 IUP. All Rights Reserved.
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