This book is written after consulting literatures, technical papers and valuable class notes in the microwave field. I acknowledge with due courtesy to the sources consulted in preparation of this book. With advancement of the society and due to its diverse applications in different fields like wireless communications, radio astronomy, long distance communications, defense navigation, remote sensing and study of chemical and physical properties of matter the microwave and R F technologies are becoming very popular day to day. The purpose of this textbook is to initiate the students and microwave readers to the microwave technologies, one of the fastest growing fields in the today's engineering world. The motivation for writing this book came, when I was working for Central Research Lab, BEL as Research Engineer in Microwave field. This textbook is based upon my experiences as a student researcher and application engineer and is modeled from an academic course developed for Electronics Communication Engineering students as well as a handbook for practicing engineers and technicians. The book is designed to solve the basic need of the students and practicing engineers in the field of microwave engineering and highly useful to the students preparing for B.E., M.Sc, GATE, IES and UPSC examination.