Sunday, June 28, 2009

MY THESIS ABSTRACT

IN an age when access to information, communication and infotainment, any time, any place, anywhere has become a pre-requisite for modern life, it is not surprising that the wireless technology has been the focus of attention of technocrats and scientists.

The field of wireless communication has been undergoing a revolutionary growth for the last decade. This is attributed to the invention of portable mobile phones some fifteen years ago. The access of the second generation (2G) cellular communication services motivates the development of wideband third generation (3G) cellular phones and other wireless products and services, including wireless local area networks, home RF, bluetooth, wireless local loops, local multipoint distributed networks etc. The crucial component of a wireless network or device is the antenna. We can see our cities are flooded with antennas of different kinds and shapes. On the other hand for safety and portability reasons, low power, multi functional and multiband wireless devices are highly preferred. All these stringent requirements demand the development of highly efficient, low profile and small size antennas that can be embedded into wireless products.

In the last two decades, two classes of novel antennas have been investigated. They are the Microstrip Patch Antenna (MPA) and the Dielectric Resonator Antenna (DRA). Both are highly suitable for the development of modern wireless communications. The use of dielectric resonator antenna was first proposed by Prof. S. A. Long in the early nineteen eighties. DRA has negligible metallic loss, and hence it is highly efficient than its counterpart when operated in microwave and millimeter wave frequencies. Also low loss dielectric materials are now easily available commercially at very low cost, which attracts more system engineers to choose dielectric resonator antenna to design their wireless products.

Dual or multifrequency operation is highly attractive in current wireless communication systems. If a single DRA can support multiple frequencies, then there is no need for multiple single frequency antennas. Applications requiring different frequency bands can be addressed simultaneously with one radiating element. This reduces the circuit size and leads to compact systems. In addition, when multiple frequencies are located close to each other, the antenna may have a broad operating bandwidth. Many investigators have reported on DRA with dual frequency operation using various approaches. But in all these cases dual frequencies are achieved by using either dual feed lines or multiple radiating elements or hybrid radiating structure, which causes design complexity and large size.

In this thesis, the author proposes a new geometry of hexagonal shape DR to the DR antenna community - Hexagonal Dielectric Resonator Antenna (HDRA) for multi frequency operation with a single feed of excitation, which is the highlight of this work. These multiple frequency bands are suitable for Digital Cordless Telephones (DCT), Personal Communication Systems (PCS) and Wireless Local area Networks (WLAN) bands.

This thesis is organized into seven chapters which describe the problem addressed, methodology adopted, results obtained, comparison between measured and theoretical results, and conclusions arrived at.

First chapter explains the development of electromagnetism, microwaves and its application from the origin. Also describes the dielectric resonator antennas (DRAs), its features over conventional microstrip antennas, different coupling methods used for exciting the DRAs and different geometries of DRAs already developed. The last section of this chapter gives a comparative study of different numerical methods used for modeling the antenna.

Chapter II provides the review of dielectric resonator antennas from its beginning to the current development. It includes the different coupling mechanism used to excite the DRAs, various geometries of DRAs developed, different techniques for improving the bandwidth, gain and the sequential theoretical analysis of DRAs. The diverse methods for producing circular polarization, air gap effect on resonant frequency and bandwidth, variety of techniques for producing multi frequency operation are reviewed in chronological order.

Chapter III describes the research methodology opted for this work. The experimental setup used for measuring the return loss, radiation pattern, gain and polarization is explained. Moreover it describes the simulation software used for characterizing the hexagonal dielectric resonator antenna.

The step-by-step development of hexagonal dielectric resonator antenna from the basic material is explained in chapter IV. It includes weighing, mixing, sintering, pressing, shaping etc. The setup used for measuring the dielectric permittivity of the material is also explained.

In Chapter V, the first part introduces the new hexagonal shaped dielectric resonator antenna with coaxial feed as excitation. The optimizations of coaxial probe length, probe feed location and aspect ratio of HDRA are performed experimentally. Besides, it explains the radiation pattern, gain and polarization of the antenna for different bands using the coaxial feed excitation. The second part explains the HDRA characteristics using microstrip feed excitation. A comparison of experimental results with the simulated results, using Ansoft HFSS, is also included in this chapter.

The theoretical study using finite difference time domain (FDTD) method for modeling the microstrip fed and coaxial fed HDRA is explained in chapter VI. It describes the theoretical concepts of FDTD in electromagnetics and the perfect matched layer (PML) concepts for absorbing boundary condition (ABC). All the necessary equations for three-dimensional electric and magnetic field variables are derived from the fundamental Maxwell’s curl equations and are given in this chapter. It also uses Lubber’s feed techniques for reducing the number of time steps required for modeling the whole structure. The FDTD results are compared with the measured values.

Chapter VII provides the conclusions and highlights drawn from this work. Advantages of new geometry hexagonal DRA and its possible applications in wireless communication are specified. Furthermore, it gives the future scope of the work in this area.

There are two Appendices included.

In Appendix – A, a metal-coated cylindrical dielectric resonator antenna for producing multiple resonances is given. Coaxial probe is used for exciting the cylindrical DRA. All the characteristics of the antenna are explained in this section.

In Appendix – B, the development of a novel coupling media and phantom material constituent for microwave medical imaging applications using sodium meta silicate gel is explained. Dielectric parameters, heating and absorption coefficient of this material are studied and discussed. Comparative studies of the suitability of gel with various biological tissues are also given in the last part.

In view of the fact that, microwave medical tomography is promising a novel non- hazardous method of imaging for the detection of tumors in soft tissues. The tomographic set up consists of antennas, coupling media and the object to be imaged. The antenna must be operated at ISM frequency. The purpose of coupling media is to enhance the coupling of electromagnetic energy between the antenna and the object to be imaged. The object is placed at the center of the imaging set up from where the scattered microwave data is collected and analyzed at the various locations of the receiver and the orientation of the object. As the HDRA developed in the core work of the thesis operates at 2.4 GHz-ISM frequency can as well be used in tomographic set up.

RECIEVING GOLD MEDAL FROM CUSAT VC [1999]

SCHOLARLY WORK AND SERVICES & PROJECTS HANDLED

o Reviewer, International Journal Progress in Electromagnetic Research and Electromagnetic Waves and Application (PIER & JEMWA – since 2006).

o Chairman, board of Studies, Electronics, University of Calicut, Kerala, India (2005-2006)

o Member, board of Studies, Electronics, University of Calicut, Kerala, India (Since 2007)

o Subject expert for appointing lecturers in colleges, University of Calicut, India (2004-2007).

o National Service Scheme programme officer, W.M.O College, University of Calicut, India (2001-2003)

o National Service Scheme Programme co-ordinator, National integration camp, University of Calicut, India (2003)

Projects handled

· Microwave Imaging of Biological Objects for Medical Applications using Free Space Complex Permittivity measurements 2004-2005

· Development of millimeter wave antennas at 60GHz 2008-2009

MY PROGRAMMING SKILLS

  • High-level languages: C, C++, FORTRAN, BASIC, VHDL.
  • Operating systems: Dos, Windows 2000/Xp, Vista.
  • Design automation tools: Xilinx FPGA.
  • Algorithm development environments: MATLAB

§ Assembly language: 8085

§ General Applications: MS office

MY TECHNICAL SKILLS

  • Experience in doing measurements using free space method from 2 GHz to 110GHz

· Experience in Microwave and Millimeter wave Antennas design using Ansoft HFSS, Ansoft Designer, CST Microwave studio.

· Proficient in Finite Difference Time Domain (FDTD) electromagnetic modeling

· Experienced in using PNA 8362B Network Analyzer, Vector Network Analyzer HP 8510C and 8714ET.

  • Experience in carrying out antenna measurements in Anechoic Chambers
  • Hands-on experience in building of antenna prototypes using photolithography and antenna experimental work.

INTERNATIONAL VISITS

* Visited Queen’s University, Belfast, Northern Ireland, UK to present a paper on wearable antennas, during 3rd April 2007 to 7th April 2007 .

* Postdoc Research Associate at the Electrical Engineering Department, University of Arkansas, USA

* Postdoc at Institute of Electronics and Telecommunication of Rennes , University of Rennes1, France

* Visited European Space Agency Centre-ESTEC, Noorwidjik, Amsterdam, Netherland,May 2009 for Research Paper presentation.

MY EXPERIENCES

Ø PostDoc, Microwave and Antennas Group/Millimeter antennas team, Institute of Electronics and Telecommunication of Rennes (IETR), University of Rennes1, France, (September 2008 - 2009). (Millimeter wave antenna development ( 60GHz) for indoor communication)

Ø Postdoctoral Research Associate at the Electrical Engineering Department, University Arkansas, USA (2008) (Microwave and millimeter wave material characterization for imaging, imaging of Radome samples from US Airforce and Metamaterial Research)

Ø Senior Research Fellow at Department of Electronics, Cochin University of Science and Technology, India (2005-2007). (Microwave dielectric resonator antennas research)

Ø Lecturer Department of Electronics, WMO college, University of Calicut, India (1999 - 2005 ). ( Teaching and Research - Electromagnetics)

Ø 5 years of teaching experience at graduate level (Electromagnetic theory, RF & Microwave theory, Control systems, Digital & analog systems, Digital signal processing, Microprocessors etc).

Ø More than 5 years of research experience in Microwave and Millimeter wave antennas, Microwave communication, microwave imaging, FDTD mathematical modeling, HFSS, CST simulation software's, Metamaterial, etc.

AWARDS & ACHIEVEMENTS

v Received CNRS fellowship (France) for doing research at Institute Fresnel, France (2007).

v Included in the First edition of who’s who in Asia in the field of Engineering (2006-2007)

v Authored/co-authored 35 research papers in International Journals such as IEEE IEE Electronics Letters, Microwave and Optical Technology Letters etc. and in conference proceedings.

v Jury member in PhD defence committe at university of Marne la Vallée, Paris , france

v Awarded research fellowship through Faculty Improvement Programme (FIP) for undertaking doctoral research work by University Grants Commission (UGC), under the Ministry of Human resources development, Govt. of India, India.(2005-2007)

v Qualified UGC-NET test for lecturers conducted by University Grants Commission, Ministry of Human Recourses Development, Govt. of India. In India this test is mandatory for the post of Lecturer appointment in the Universities and Colleges (2001)

v First Rank Holder, M.Sc Electronics examination, Cochin University of Science and Technology ( CUSAT) Kochi, India (1999)

v Recipient of K.G Nair Endowment gold medal for securing first Rank in Masters in Electronics, which was one of the honorable award given to the most talented student of the Department of Electronics, CUSAT, India (1999)

v M.E.S Merit Scholarship for studying Master of Science (1996-1998).

v Topper in B.Sc Degree examination (90.8%) at M.E.S College, Under University of Calicut, Kerala, India (1996)

MY PUBLICATIONS

  1. Hamsakutty Vettikalladi, Olivier Lafond, Mohamed Himdi , High-Gain Broad-band Superstrate Millimeter wave Antenna for 60GHz Indoor Communications, 5th ESA Workshop on Millimetre Wave Technology and Applications and 31st ESA Antenna Workshop , 18 - 20 May 2009, ESTEC, Noordwijk, The Netherlands.
  2. Hamsakutty Vettikalladi, Olivier Lafond, Mohamed Himdi , High Gain 60GHz Parasitic Patch Antenna With Superstrate, The 20th IEEE Personal, Indoor and Mobile Radio Communications Symposium 2009 (PIMRC09), sept 13-16. Tokyo, Japan.(Paper submitted)
  3. A.V. Praveen Kumar, V. Hamsakutty, Jaimon Yohannan and K. T. Mathew, "A Wideband Conical Beam Cylindrical Dielectric Resonator Antenna’s”, IEEE Antennas and Wireless Propagation Letters, vol.6, 2007, pp. 15-17.
  4. V. Hamsakutty, Jaimon Yohannan, K. T. Mathew, “Effect of Aspects ratio on the performance of Hexagonal dielectric resonator antenna”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI 2007, June, 2007, USA.
  5. V. Hamsakutty, A.V. Praveen Kumar, Jaimon Yohannan, K. T. Mathew, “ Hexagonal Dielectric Resonator Antenna for 2.4GHz WLAN Applications”, Microwave and Optical Technology Letters(USA), 20 Nov, 2006.
  6. A.V. Praveen Kumar, V. Hamsakutty, Jaimon Yohannan and K. T. Mathew, “A strip loaded dielectric resonator antenna for circular polarisation, Microwave and Optical Technology Letters(USA), Volume 48, Issue 7 , Pages 1354 – 1356, July 2006.
  7. A.V.Praveen Kumar, V. Hamsakutty, Jaimon Yohannan, K. T. Mathew Microstripline Fed Cylindrical Dielectric Rresonator Antenna With a Coplanar Parasitic Strip”, Progress in Electromagnetic Research (USA),60,143-152,2006.
  8. V. Hamsakutty, A.V. Praveen Kumar, Jaimon Yohannan,G. Bindu and K. T. Mathew, “Coaxial Fed Hexagonal Dielectric Resonator Antenna for multi- frequency operation”, Microwave and Optical Technology Letters(USA), Volume 48, Issue 5 , Pages 878 – 880, May 2006.
  9. A. V. Praveen Kumar, V. Hamsakutty, Jaimon Yohannan, K. T. Mathew*, “Microstripline fed Half-Cylindrical Dielectric Resonator Antenna for 2.4 GHz WLAN application”, Microwave and Optical Technology Letters(USA), Volume 48, Issue 4 , Pages 724 – 726, April 2006
  10. V. Hamsakutty, A.V. Praveen Kumar, Jaimon Yohannan, K. T. Mathew, “Coaxial Fed Hexagonal Dielectric Resonator Antenna for Circular Polarization”, Microwave and Optical Technology Letters (USA), Volume 48, Issue 3 , Pages 581 – 582, March 2006
  11. V. Hamsakkutty and K. T. Mathew, “ Dual frequency hexagonal dielectric resonator antenna for DCT and WLAN applications”, National Symposium on Antennas & Propagation December 14-16, 2006, Department of Electronics, Cochin University of Science and Technology, Kochi-682 022, Kerala, India.
  12. V. Hamsakkutty, A. V. Praveen Kumar, Jaimon Yohannan, K. T. Mathew, “Hexagonal dielectric resonator antenna for multifrequency operation”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI 2006, July, 2006, Alberque, 9-13,USA.
  13. Jaimon Yohannan,V. Hamsakkutty, A. V. Praveen Kumar, Vinu Thomas, G. Bindu and K. T. Mathew, “A rectangular dielectric resonator band stop filter”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI , 2006, July, 2006, Alberque, 9-13,USA.
  14. A. V. Praveen Kumar, V. Hamsakkutty, Jaimon Yohannan, K. T. Mathew,Half split cylindrical dielectric resonator antenna for 2.4GHz wireless application”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI, 2006, July, 2006, Alberque, 9-13,USA.
  15. A. Lonappan, V. Thomas, G. Bindu, V. Hamsakutty, and K. T. Mathew “Analysis Of Human Breast Milk At Microwave Frequencies”, Progress in Electromagnetic Research (USA), 2005
  16. V. Hamsakutty, A.V. Praveen Kumar, G. Bindu, Vinu Thomas, Anil Lonappan, Jaimon Yohannan, K. T. Mathew “A Multi- Frequency Coaxial Fed Metal Coated Dielectric Resonator Antenna”, Microwave and Optical Technology Letters(USA), Volume 47, Issue 6 , Pages 573 - 575 Dec- 2005.
  17. Vinu Thomas, C. Gopakumar, Jaimon Yohannan, Anil Lonappan, G. Bindu, A.V. Praveen Kumar, V. Hamsakutty, K. T. Mathew “A Novel Technique for Localizing the Scatterer in Inverse Profiling of Two Dimensional Circularly Symmetric Dielectric Scatterers Using Degree of Symmetry and Neural Networks” Journal of Electromagnetic Waves and Applications(USA), Vol. 19, No. 15, 2113–2121, 2005
  18. G.Bindu , Anil Lonappan, Vinu Thomas, A. V. Praveen Kumar, V Hamsakutty, C.K. Aanandan, K.T Mathew “ Two Dimensional Microwave Tomographic Imaging of Low Water Content Tissues” , Microwave and Optical Technology Letters (USA) Vol. 46, No.6, pp 599-601, 20th September 2005
  19. Vinu Thomas, C. Gopakumar, A. V. Praveen Kumar, V. Hamsakutty, Anil Lonappan, G. Bindu, K. T. Mathew “A novel technique for reducing the imaging domain in microwave imaging of two dimensional circularly symmetric scatterers” , Microwave and Optical Technology Letters (USA) Vol. 44, No. 5, pp 423-427, 5th March 2005
  20. V. Hamsakutty, A.V.Praveen Kumar, Jaimon Yohannan, Kattakkal Thomas Mathew, “Coaxial Fed Hexagonal Dielectric Resonator Antenna”, Asia Pacific Microwave conference, Dec4-7 2005, china.
  21. Praveen Kumar A.V., Hamsakutty V, Jaimon Yohannan, Mathew K.T. “Microstripline Fed Cylindrical Sector Dielectric Resonator Antenna”, Asia Pacific Microwave conference, Dec4-7 2005, china.
  22. G.Bindu, Anil Lonappan, Vinu Thomas, Jaimon Yohannan, V. Hamsakutty, C.K.Aanandan and K.T.Mathew, “coplanar stripline fed wide band bowtie antenna for ground penetrating radar”, URSI, New Delhi 2005
  23. Jaimon Yohannan, A. V. Praveen Kumar, V. Hamsakkutty, Vinu Thomas and K. T. Mathew, “Synthesis of dielectric resonator for microwave filter designing”, Electromagnetic Research Symposium, PIERS 2005, August 22-26, 2005, Hangzhou, China.
  24. Vinu Thomas, C. Gopakumar, Jaimon Yohannan, Anil Lonappan, G. Bindu, A.V. Praveen Kumar, V. Hamsakutty, K. T. Mathew “A Novel Technique for Localizing the Scatterer in Inverse Profiling of Two Dimensional Circularly Symmetric Dielectric Scatterers Using Degree of Symmetry and Neural Networks” Electromagnetic Research Symposium, PIERS 2005, August 22-26, 2005, Hangzhou, China
  25. Jaimon Yohannan, Vinu Thomas, V. Hamsakkutty, Praveen Kumar and K. T. Mathew,” Microwave ceramic resonator antenna for communication applications”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI 2005, July 3-8, 2005, Washington DC, USA
  26. A. V. Praveen Kumar, Jaimon Yohannan, Anil Lonappan, G. Bindu, Vinu Thomas, V. Hamsakkutty, K. T. Mathew, “Microstripline Fed Circular Sector Dielectric Resonator Antenna”, IEEE AP-S International Symposium and USNC / URSI National Radio Science meeting, APS/URSI 2005, July 3-8, 2005, Washington DC, USA
  27. Jaimon Yohannan, A. V. Praveen Kumar, Vinu Thomas, V. Hamsakutty, Anil Lonappan, K. T. Mathew “Half- Split Cylindrical Dielectric Resonator Antenna” Fifth International Conference on Ferroelectrics, Ferroelectrics UK 2005, April 26- 27, 2005, University of Paisley, Scotland, UK
  28. G.Bindu , Anil Lonappan,V Hamsakutty, Vinu Thomas, C.K. Aanandan, K.T Mathew “ Microwave Characterisation of Breast Phantom Materials” , Microwave and Optical Technology Letters (USA) Vol. 43, No.6, pp 506-508, 20th December 2004
  29. Vinu Thomas, C. Gopakumar, Anil Lonappan, G.Bindu, V Hamsakutty, K.T Mathew “ Microwave Imaging of Two-Dimensional Dielectric Cylinders with a Multiscaled Frequency Hopping Approach” , Microwave and Optical Technology Letters (USA) Vol. 43, No. 4, pp 353-355, 20th November 2004
  30. Anil Lonappan, V Hamsakutty, G.Bindu, Joe Jacob, Vinu Thomas, K.T Mathew “ Dielectric properties of human urine at microwave frequencies” , Microwave and Optical Technology Letters (USA) Vol. 42, No.6, pp 500-503, 20th September 2004
  31. G.Bindu ,V Hamsakutty, Anil Lonappan, Joe Jacob, Vinu Thomas, C.K. Aanandan, K.T Mathew “ Wide Band Bowtie Antenna with Coplannnar Stripline Feed” , Microwave and Optical Technology Letters (USA) Vol. 42, No. 3, pp 222-224, 5th August 2004
  32. Vinu Thomas, C. Gopakumar, A.V. Praveen Kumar, V. Hamsakutty, Jaimon Yohannan, K. T. Mathew, “Imaging Domain Reduction in Microwave Imaging of Two Dimensional Circularly Symmetric Dielectric Scatters Using Degree Symmetry Vector” International Conference on Photonics, Optoelectronics and Fiber optics, SPIE 2004, December 9-11, 2004, Cochin, India
  33. V Hamsakutty, Anil Lonappan, Joe Jacob, G.Bindu , Vinu Thomas, A. V. Praveen Kumar, K.T Mathew “ Biomedical Applications of Sodium Meta Silicate Gel as Coupling medium for Microwave Medical Imaging” , IEEE AP-S International Symposium and USNC/URSI National Radio Science Meeting, APS/URSI 2004, June 20-26, 2004, Monterey, California, USA
  34. Jaimon Yohannan, Vinu Thomas, V. Hamsakkutty, Praveen Kumar , K. T. Mathew,”Sr(1-X/2)NaXNb2O6 ceramic dielectric resonator antennas”, National Symposium on Antennas & Propagation December 21-23, 2004, Department of Electronics, Cochin University of Science and Technology, Kochi-682 022, Kerala, India.
  35. V Hamsakutty, Anil Lonappan, Joe Jacob, Jaimon Yohannan, Vinu Thomas, G.Bindu, K.T Mathew “ A Novel Coupling medium for Microwave Medical Imaging” , IEE Electronic Letters (UK), Vol. 39, No. 21, pp 1498-1499, 16th October 2003