SIMULATION OF NEAR-FIELD GENERATED BY S-BAND RECTANGULAR HORN ANTENNA ARRAY FOR HYPERTHERMIA THERAPY APPLICATIONS USING 4NEC2 SOFTWARE Dwija Reddy Aloori B.Tech, J N T University, India, 2008 Sandhya Ramagiri B.Tech, J N T University, India, 2008 PROJECT Submitted in partial satisfaction of the requirements for the degrees of MASTER OF SCIENCE in COMPUTER ENGINEERING and ELECTRICAL AND ELECTRONIC ENGINEERING at CALIFORNIA STATE UNIVERSITY, SACRAMENTO FALL 2010 SIMULATION OF NEAR-FIELD GENERATED BY S-BAND RECTANGULAR HORN ANTENNA ARRAY FOR HYPERTHERMIA THERAPY APPLICATIONS USING 4NEC2 SOFTWARE A Project by Dwija Reddy Aloori Sandhya Ramagiri Approved by: __________________________________, Committee Chair Preetham B. Kumar, Ph.D. __________________________________, Second Reader Russell Tatro, M.S. ___________________________ Date ii Students: Dwija Reddy Aloori Sandhya Ramagiri I certify that these students have met the requirements for format contained in the University format manual, and that this project is suitable for shelving in the Library and credit is to be awarded for the Project. ___________________, Department Chair _________________ Suresh Vadhva, Ph.D. Date Department of Computer Engineering Department of Electrical and Electronic Engineering iii Abstract of SIMULATION OF NEAR-FIELD GENERATED BY S-BAND RECTANGULAR HORN ANTENNA ARRAY FOR HYPERTHERMIA THERAPY APPLICATIONS USING 4NEC2 SOFTWARE by Dwija Reddy Aloori Sandhya Ramagiri This project will focus on the application of advanced electromagnetic simulation software 4nec2, for the near-field characterization of a 3-element S-band array of horn antennas, operating at the ISM frequency of 2.4 GHz. Previous modeling efforts have shown a significant difference between simulated and measured data. The key effort in this project will be to minimize the difference between simulated and measured data using 4nec2 software. This study has useful application in the area of clinical hyperthermia, which is defined as the therapeutic treatment of tumors in the body by heating caused by focused RF or microwave radiation. The 3-element array consists of a central focusing element and two surrounding directing elements. The focusing element can be axially adjusted and surrounding elements are fixed to focus the beam of a required point, which is necessary in hyperthermia treatment. , Committee Chair Preetham B. Kumar, Ph.D ______________________ Date iv ACKNOWLEDGEMENT Man has made language to express his feelings. Yet, we find ourselves short of words when it comes to thanking all those who have rendered necessary help for the completion of this project. First and foremost we would like to express our gratitude and thanks to our advisor, committee chair and graduate coordinator Dr. Preetham Kumar, for his expert guidance and constant support throughout this project. His openness and enthusiasm have taught us correct way of working with new technologies and have improved our knowledge of the subject. We are extremely thankful to Mr. Russell Tatro our second reader, for reviewing this work and for his valuable suggestions in improving the same. It is our duty to recognize the efforts of Computer Engineering and Department and the management for creating an interactive atmosphere for learning. We would also like to take this opportunity to thank the considerate faculty and staff of Computer Engineering Department who have been encouraging us throughout our curriculum. At the end we would like to extend our thanks to our parents for their constant encouragement and to all those who have played a small but important role in this project but could not be individually named here. v TABLE OF CONTENTS Page Acknowledgement .............................................................................................................. v List of Tables ................................................................................................................... viii List of Figures .................................................................................................................... ix Chapter 1. INTRODUCTION ...........................................................................................................1 2. HYPERTHERMIA TREATMENT AND ITS APPLICATIONS .................................. 3 2.1 Introduction to Hyperthermia .....................................................................................3 2.2 Types of Hyperthermia ..............................................................................................4 2.3 Risks of Hyperthermia ...............................................................................................6 2.4 Effects of Hyperthermia .............................................................................................7 2.5 Future Scope of Hyperthermia ...................................................................................8 3. NUMERICAL ELECTRO MAGNETICS CODE(4NEC2) ........................................... 9 3.1 Introduction to 4NEC2 ...............................................................................................9 3.2 Additional Features of 4NEC2 .................................................................................10 3.3 4NEC2 Project Flow ................................................................................................10 3.4 Configuration ...........................................................................................................11 3.5 Steps for drawing a geometrical model ....................................................................11 4. DESIGN AND SETUP OF S-BAND RECTANGULAR HORN ARRAY ................. 17 4.1 Measurement of near field of single horn antenna along the axis of the antenna ....18 4.2 Measurement of Z-axis near field of three element horn antenna array ..................19 vi 5. SIMULATION RESULTS OF S-BAND RECTANGULAR HORN ARRAY ........... 24 5.1 4NEC2 Setup, simulation and array parameters ......................................................24 5.1.1 All array elements in the same line ...............................................................25 5.1.2 Center array element is 5.08cm behind the other two elements ...................30 5.1.3 Center array element is 10.16cm behind the other two elements .................35 5.2 Comparison of measured and simulated array performance ....................................40 6. CONCLUSION AND SCOPE FOR FUTURE WORK ................................................43 References ..........................................................................................................................45 vii LIST OF TABLES Page 1. Table 5.1 Comparison of Measured and Simulated data……………………………41 viii LIST OF FIGURES Page 1. Figure 3.1 Main window ............................................................................................. 12 2. Figure 3.2 Geometry edit window .............................................................................. 13 3. Figure 3.3 Geometry edit window showing voltage source at a point ........................ 13 4. Figure 3.4 Geometry edit window showing frequency/ground selection .................... 14 5. Figure 3.5 Geometry edit window showing conductivity and dielectric constant ...... 15 6. Figure 3.6 To calculate the NEC output data .............................................................. 15 7. Figure 3.7 Window showing selection of pattern ....................................................... 16 8. Figure 3.8 Window showing near field pattern and its equivalent values .................. 16 9. Figure 4.1 Photograph of 3-element horn array set up in Lab .................................... 17 10. Figure 4.2 Experimental set up for single element antenna ...................................... 18 11. Figure 4.3 Axial near-zone electric field of single horn antenna ............................. 19 12. Figure 4.4 Experimental setup for 3-element horn array with 3 elements in line ... 20 13. Figure 4.5 Experimental setup for 3-element horn array with central element 5.08 cm behind outer directing elements ............................................................. 21 14. Figure 4.6 Experimental setup for 3-element horn array with central element 10.16 cm behind outer directing elements .............................................. 22 15. Figure 4.7 Consolidated beam focusing demonstration for 3-element horn array .... 23 16. Figure 5.1a 4NEC2 schematic when the center waveguide is in line with other two elements ................................................................................................. 25 17. Figure 5.1b 4NEC2 input .nec file when all array elements are in the same line .... 26 ix 18. Figure 5.1c Electric field intensity when all waveguide elements are in line .......... 27 19. Figure 5.1d Rectangular plot of near field pattern when all array elements are in line ......................................................................................................... 28 20. Figure 5.1e Electric field along a YZ plane at the highest field point ...................... 29 21. Figure 5.1f 4NEC2 schematic when the center element is 5.08cm behind the other two elements .......................................................................................... 30 22. Figure 5.1g 4NEC2 input .nec file when the center element is 5.08cm behind the other elements ....................................................................................... 31 23. Figure 5.1h Electric field intensity when the center