NOVEL RECONFIGURABLE PRINTED ANTENNAS

Transcription

1 NOVEL RECONFIGURABLE PRINTED ANTENNAS MANOJ SINGH PARIHAR CENTER FOR APPLIED RESEARCH IN ELECTRONICS (CARE) INDIAN INSTITUTE OF TECHNOLOGY DELHI JUNE 2012

2 NOVEL RECONFIGURABLE PRINTED ANTENNAS by MANOJ SINGH PARIHAR Submitted in fulfillment of the requirement of degree of Doctor of Philosophy to the Center for Applied Research in Electronics (CARE) Indian Institute of Technology Delhi JUNE 2012

3 Indian Institute of Technology Delhi (IIT D), New Delhi-2012

4 To My Family

5 CERTIFICATE This is to certify that the work reported in the thesis entitled Novel Reconfigurable Printed Antennas, being submitted by Mr. Manoj Singh Parihar for the award of the degree of Doctor of Philosophy (Ph.D.) to the Indian Institute of Technology Delhi, New Delhi, is a record of original bonafide research work carried out by him under our guidance and supervision. The results contained in it have not been submitted in part or full to any other university or institute for the award of any degree or diploma. We certify that he has pursued the prescribed course of research. ANANJAN BASU Associate Professor SHIBAN K. KOUL Professor Center for Applied Research in Electronics Indian Institute of Technology Delhi, New Delhi i

6 ACKNOWLEDGEMENT I would first like to reserve my deep sense of gratitude and sincere thanks to my Supervisor Prof. Shiban K Koul, Centre for applied research in Electronics (CARE), Indian Institute of Technology (IIT) Delhi for giving me the opportunity to work in the esteemed institute. His generous direction, avid counseling, encouragement, immense cooperation, advice and welcoming support have been invaluable throughout my research. I would like to thank my Co-supervisor Dr. Ananjan Basu, Associate Professor, CARE, IIT Delhi, for his most encouraging attitude, vision, constant support, and critical evaluation rendered to me throughout entire phase of research work. I want to give special thanks to Dr. Mahesh P Abegaonkar for the time and advice he has graciously given to me while working with the RF and Microwave Group. I express my sincere thanks to the research board of Institute of Electronics and Telecommunication Engineers (IETE), New Delhi for awarding research fellowship to me for a period of eighteen month. My sincere thanks are also due to my colleagues Preeti Sharma, Mithlesh Kumar, Sandeep Chautervedi, Madhur Deo Upadhayay, Lalithendra Kurra, Sukomal Dey, Ritabrata Bhattacharya, Srujana Kagita, Saurabh Pegwal, Pooja Prakash and Ravi Dutt Gupta of RF and Microwave laboratory, CARE for their support in various ways. I also thank fellow friends of the department and outsides, S Lokesh, Atul Vir Singh, Ramswaroop Meena, John Thomas and other research scholars and M. Tech students with whom I shared my thoughts and ideas during the course of my PhD. I thankfully acknowledge the technical support and cooperation of S P Chakraborty in different ways during the PhD experimentation phase. Support from Ashok Pramanik and Pradeep Saxena (CARE workshop) is greatly felt and dully acknowledged. ii

7 The warmth & encouragement provided by my in laws is sincerely felt and duly acknowledged. Constant affection and guidance provided by my mother in law, Ms Meera Kushwah and father in law, Mr Jitendra Singh Kushwah is deeply felt. Finally saving the best for the last, my family. It would be belittling to express the boundless love, limitless patience, encouragement, affection and support I received from my father, Shri Sawai Singh Parihar and mother Ms Urmila Singh. I thank my younger brothers Kunwar Singh and Yogendra Singh for their kind cooperation and affection. Boundless love and playful environment provided by my little son Harsh has been lovingly remembered. Last, but not least, I would like to thank my wife Vijeta Singh for her understanding and love during the period of my research. Her support and encouragement was in the end what made this dissertation possible. (MANOJ SINGH PARIHAR) iii

8 ABSTRACT This dissertation deals with the analysis, design, simulation and fabrication of different types of reconfigurable antennas. The developed antennas include frequency reconfigurable antennas, radiation pattern reconfigurable antennas, and polarization reconfigurable antennas. To start with, concept of reconfigurability in antennas is described and then details of the antennas along with simulation and measured results are given. Different frequency reconfigurable antennas are described that include dual frequency reconfigurable antenna, tri-band frequency reconfigurable antenna, continuous frequency reconfigurable antenna and dual-band tri-state frequency reconfigurable antenna. In all these antennas, P-I-N diodes are used as the switching device. To obtain reconfigurable dual-band frequency response, conventional microstrip fed rectangular patch is used which is connected to an additional small parasitic patch through a P-I-N diode. The measured performance for dual-band antennas is very close to the predicted performance using simulations. It was seen that the frequency shift when the diode was ON could be positive as well negative. Design, simulation, fabrication and measurement of a novel microstrip fed reconfigurable antenna to provide tri-band operation is presented next. Reconfigurable triband operation is obtained by connecting an additional patch to the conventional microstrip fed rectangular patch through two P-I-N diodes with opposite orientation. In addition to these two configurations of the frequency reconfigurable antennas, a continuous frequency reconfigurable antenna is implemented and tested. Here, a varactor diode is integrated between the radiating edge of the first patch and an additional patch to achieve continuously variable frequency with different reverse bias voltages of the diode. The maximum frequency tunability obtained in the fabricated antenna is around 2.3 GHz. iv

9 Design, development, fabrication and characterization of the dual-band tri-state frequency reconfigurable monopole antenna is also presented in this thesis. Two P-I-N diodes with opposite orientation are incorporated in the dual band monopole antenna layout to obtain three states of frequency response. The antenna operates either at 2.4 GHz or 5 GHz or at both 2.4 and 5 GHz. The proposed antenna is compact and easy to fabricate and thus suitable for IEEE802.11a/b WLAN communication applications. Design, development, fabrication and characterization of reconfigurable radiation beam pattern antenna and polarization reconfigurable antenna for wireless communication systems are described next. In reconfigurable radiation pattern antenna, conventional three element series fed array is used in which the first element of the array is connected to other two elements using single P-I-N diode. The broad-side radiation pattern (E-plane) obtained shows that the antenna displays narrow beam with half power beam width (HPBW) under forward bias state and broad beam radiation with HPBW under reverse bias condition with almost same frequency response in both the states of the diode. Microstrip fed patch antenna with circular corner truncation to achieve polarization reconfigurability (linear polarization (LP), right hand circular polarization (RHCP) and left hand circular polarization (LHCP)) is simulated, fabricated and characterized. To achieve reconfigurable polarizations, four P-I-N diodes are used to connect circular truncated square patch to four small circular sector patches. The measured axial ratio bandwidth obtained in the proposed antenna over the measured resonant frequency is 56 MHz for RHCP and 53 MHz for LHCP with < 2 db axial ratios in both polarizations. Using time domain analysis, switching characterization of the antenna is reported. Polarization switching from linear to circular can be achieved in 30ns and one circular polarization to the other can be achieved in 55 ns, using a single BJT- based diode driver circuit. v

10 Finally, a double slot antenna fed by Wilkinson power divider has been utilized to demonstrate a reconfigurable null scanning antenna. The antenna demonstrates strong rejection of signal coming from a prescribed direction. In this antenna structure, three different null positions are obtained at 0, +50 and -60 by using three bias states. Reconfigurable null scanning operation is achieved by controlling the lengths of power divider using P-I-N diode switches. In reconfigurable null broadening antenna, array of four slot antennas exited by a 4-to-1 ways Wilkinson power divider is introduced. Null broadening is achieved by providing a phase delay of 90 in second and fourth element of array. vi

11 CONTENTS Certificate Acknowledgement Abstract Contents List of Figures List of Tables i ii iv vii x xix 1 INTRODUCTION 1.1 Reconfigurable antennas Motivation RF Switches Mechanical switches P-I-N diode switches Field Effect Transistor switches RF MEMS switches Antenna field simulators Executive summary Scope and organization of thesis 14 2 FREQUENCY RECONFIGURABLE ANTENNAS 2.1 Introduction Motivation Modeling of reconfigurable antennas Modeling methods Antenna design for frequency reconfigurability Antenna design for a given reference frequency Antenna for dual band frequency operation Parametric study of dual band frequency antenna Final dual frequency antenna configurations Improved modeling of dual band reconfigurable antenna Results and discussion 41 vii

12 2.5 Tri-band frequency reconfigurable antenna Geometry of switchable tri-band frequency antenna Parametric study of tri-band reconfigurable antenna Operational mechanism Biasing circuit for p-i-n diodes Modeling of antenna using actual diode model Results and discussion Continues frequency reconfigurable antenna Measured results and discussion Tri-state dual-band frequency reconfigurable antenna Reference antenna for tri-state dual- band frequency reconfigurable antenna Tri state frequency reconfigurable antenna Switch modeling of tri-state reconfigurable antenna Measured results and discussion Dual-band antenna Results and discussion Conclusion 79 3 PATTERN AND POLARIZATION RECONFIGURABLE ANTENNAS 3.1 Radiation pattern reconfigurable antenna Series fed array pattern reconfigurable antenna Series-fed arrays Antenna design and layout Simulation and experimental results Reconfigurable polarization antenna Fundamental theory of operation Reconfigurable circular polarization antenna with circular truncated corners Antenna design for switchable polarization operation Operational mechanism Modeling of the antenna Simulated and experimental results Transient analysis of switchable polarization antenna 110 viii

13 3.2.8 Experimental results of transient analysis Conclusion RECONFIGURABLE NULL STEERING AND NULL BROADENING ANTENNA 4.1 Introduction Reconfigurable null steering slot antenna with strong spurious rejection capability Enhanced spurious rejection by slot antenna Antenna design Operational mechanism Simulation and experimental results Reconfigurable null broadening slot antenna array Increasing the angular range for spurious rejection by slot antenna Modeling of slot antenna array Measured results Conclusion CONCLUSIONS AND FUTURE SCOPE 5.1 Summary of the results Scope for future work 154 REFERENCES 156 BIBLIOGRAPHY 161 APPENDIX 169 LIST OF PUBLICATIONS 174 BRIEF BIO DATA OF AUTHOR 176 ix