Variable permittivity dielectric material loaded stepped-horn antenna

ACKNOWLEDGMENTThe preparation of this dissertation was assisted by many people. First of all, I would liketo thank my supervisor Dr. Edip Niver who has provided valuable guidance for my lifeand my research. I would like to express my sincere thanks to Dr. Gerald Whitman forhis valuable insight into research issues and his deep interest. I would also like to expressmy gratitude to Dr. Haim Grebel for his interest in my research. My gratitude is expressedto Dr. Koray E. Akdogan and Dr. Ken Chin for serving as commitee members and forproviding useful comments. I would also like to thank to Dr. Ronald Kane for his concernabout my graduate studies.I would like to give my special thanks to Igor Stanojev who has always been such agreat friend. His support has meant a lot to me than he could possibly realize. Also I wouldlike to give my special thanks to Nikolaus Lehmann for his unbelievable support by takingcare of everything for me from my presentation suit to fixing LaTeX problems. I am reallygrateful to Jingdi Zeng, Didem Gozupek, Gokhan Erkavun, Jordi Diaz, Zoran Latinovic,Taha Sencar and Chairat Pinthong for their friendship. I would like to thank to Ali Yaparand Funda Akleman for their encouragement from Istanbul. Without Arzu Aysu Gursoy, Iwould not be able to finish this dissertation.I will be always grateful to my parents, Tahsin and Güler Özdemir, for their endlesslove. Their immeasurable devotion and encouragement gave me the strength to pushthrough difficulties all my life. I also feel so lucky to have siblings like my brother BattalÖzdemir and my sister Fadime Ergün who both always loved and believed in me. Finally,during the last two years, whenever I felt down, I only had to look at the picture of mygorgeous niece, Ada, to be happy again.vi