Antenna Shape Prediction by Feedforward Neural Network

COPLANAR WAVEGUIDE-FED MONOPOLELIKE SLOT ANTENNA FOR ULTRA WIDEBAND APPLICATIONSBy Manoj Kumar Shrivastava

Under the guidance ofDr. Amit Kumar Singh

Department of Electronics EngineeringIT BHU, Varanasi

Institute of Technology Banaras Hindu University1Seminar on Dissertation ContentsIntroductionUltra Wideband TechnologyTypes of Feeding TechniquesUltra wideband monopole antennaApplications of UWB AntennaDesign of The Proposed AntennaSimulated and Measured ResultsParametric studySimulated and Measured ResultsConclusionReferencesInstitute of Technology Banaras Hindu University22In the ancient age, spark-gap technology was in the main root of ultra wideband antenna. Arguably, the first experiment on UWB was conducted by Hertz1 in 1893

After Hertz, Oliver lodge2 gave prominent contribution in the field of UWB antenna. In 1898

After four decades, in 1939, Carter3, who improved upon Lodges original design by incorporating a tapered feed

Institute of Technology Banaras Hindu University3Introductionwho was among the first to take the key step of incorporating a broadband transition between a feed line and radiating elements.

Deschamps4 first proposed the concept of the Microstrip antenna (MSA) in 1953. However, practical antennas were developed by Munson and Howell in the 1970s.

Finally5, it was in November 2002 when the interest for UWB systems was greatly magnified by the decision of the United States frequency regulating body, the Federal Communications Commission (FCC)Institute of Technology Banaras Hindu University4After, 2002 UWB antenna got new direction and wide amplitude of uses. Innovative research and design are taking place day by day.Institute of Technology Banaras Hindu University5Ultra Wideband Technology5Federal Communications commissions(FCC)Bandwidth ranging from 3.1GHz to 10.6GHz Low Emission power (-41.3dBm/MHz)Radiation pattern should be omni-directional.

Institute of Technology Banaras Hindu University6Types of Feeding Technique4Coaxial feedMicrostrip line feedAperture couplingProximity-coupled feedCoplanar waveguide feed

Institute of Technology Banaras Hindu University7Coplanar waveguide feed6

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Advantages of CPW fed are low radiation loss, less dispersion, easy integrated circuits wider bandwidth, better impedance matching, and easy integration with active devices or monolithic microwave integrated circuits(MMIC) and simple configuration with single metallic layer, and no via holes required. Institute of Technology Banaras Hindu University9Ultra wideband monopole antenna

There are three typical printed UWB antenna designs which has been widely suited and used in UWB systems as shown in figure

Institute of Technology Banaras Hindu University10Figure: Three typical printed UWB antennas: (a)A microstrip-fed monopole antenna; (b) a CPW fed wide slot antenna; (c) a CPW fed monopole-like slot antenna.

The antenna7 used in portable devices do not have a large ground plane but a small floating system ground plane which is used as a zero potential reference for systems. The system ground plane actually act as the other radiating element of the antenna, therefore the overall size should include both the antenna and the system ground plane.

Institute of Technology Banaras Hindu University11 Unbalanced dipoles

Figure printed UWB monopole antennas acting as asymmetrical unbalanced dipoles

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12Applications of UWB Antenna

(1) Ground penetration radar (GPR)(2) Sensing and Imaging [biomedical and military applictions](3) Testing the systems

Institute of Technology Banaras Hindu University13Design of The Proposed Antenna

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Figure: Structure of CPW-fed monopole-like slot antenna for UWB applications

Table : Optimized parameter of designed antenna

Parameters bcdefgqrstDimensions(mm)9.32.611.510.58.5615.50.91Institute of Technology Banaras Hindu University15The geometry of CPW-fed monopole-like slot antenna for UWB applications is shown in figure. The parameter of antenna is given in the table below.

The dielectric material of the antenna is FR4 ( r=4.4) and dielectric loss tangent is 0.02. The thickness of the dielectric material is 1.6mm and the dimension of patch is 25x25mm.

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Figure : prototype of proposed antenna (a) Top view (b) Back view

(a)(b)Simulated and Measured ResultsInstitute of Technology Banaras Hindu University17Figure Simulated Return loss of the proposed antennaMeasured Return lossInstitute of Technology Banaras Hindu University18Figure Measured Return loss of the proposed antenna

Comparision between measured and simulated resultReturn LossLower cut off frequency[GHz]Upper cutoff frequency[GHz]Band width[GHz]% BandwidthMeasured4.9610.395.4370.75simulated3.114.5511.45129.74Institute of Technology Banaras Hindu University19Figure Simulated H-plane radiation pattern at different frequenciesInstitute of Technology Banaras Hindu University20Figure Simulated H-plane radiation patter at different frequencies

Institute of Technology Banaras Hindu University21Gain of the antennaInstitute of Technology Banaras Hindu University22Figure Simulated gain of the designed antenna

11.6 dB gain can be achieved at frequency at

3.1GHz , which is maximum value in the pass band wher as and0.5 dB is minimum value in pas band at 12.7GHz Measured imaginary part of input impedance

Institute of Technology Banaras Hindu University23Measured real part of input impedance

Institute of Technology Banaras Hindu University24Simulated imaginary and real part of the input impedanceInstitute of Technology Banaras Hindu University25Figure Simulated imaginary and real part of the input impedance

Parametric study

varying the gap between CPW feeding stub and ground planes

Institute of Technology Banaras Hindu University26Figure Return loss for varying the gap between CPW feeding stub and ground planes

varying the patch radius of the antenna

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Figure Return losses for varying the patch radius of the antennaVarying the gap between lower ground plane and circular patch.

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Figure Return losses for varying the gap between lower ground plane and circular patch. Varying pint p

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Figure Return loss for varying the ground plane along the vertical axis CONCLUSION AND FUTURE WORKA comprehensive study of UWB antennas including design, simulation, testing and characterization is presented.

From UWB antenna design it is found that the measured impedance bandwidth is 70.75% where as simulated impedance bandwidth is 129.74%Institute of Technology Banaras Hindu University30Future scopeThis proposed antenna can be modified to be usefull in band notched UWB antennaThis can be used as directional antenna with some physical modification.Institute of Technology Banaras Hindu University31References [1] http://www.intechopen.com/books/ultra-wideband/uwb-antennas-design-and-modeling[2] O. Lodge, Electric Telegraphy, U.S. Patent 609154, August 1898[3] P.S. Carter, Short Wave Antenna, U.S. Patent2175252, October 1939[4] Girish Kumar and K. P. Ray, Broadband Microstrip Antennas (Artech House Boston London 2003 edition)[5]International Journal of Antennas and PropagationUltra-Wideband AntennasGuest Editors: James Beck er, D ejan Filipovic,Hans Schantz, and S eong-Youp Suh.2002[6]Leena Varshney, Vibha Rani Gupta, Harish kumar, Priyadarshi Suraj, CPW-Fed Broadband Microstrip Patch Antenna Published in International Journal of Advanced Engineering & Application, Jan 2011 Issue

[7] DEBATOSH GUHA AND YAHIA M.M.ANTAR; Microstrip and Printed Antennas New, Trends, Techniques and pplications.(A John Wiley and Sons, Ltd, publication, 2011)Institute of Technology Banaras Hindu University32

THANK YOUInstitute of Technology Banaras Hindu University33Institute of Technology Banaras Hindu University34