the objective of this book is to provide up-to-date information for the modern multi-function antenna system and microwave component. today, it is a trend to bundle multiple components into a single module for achieving compact and multi-functional wireless communication systems. in the last two decades, the multi-function concept has already been extensively applied to miniaturize various active and passive radiofrequency (rf) devices. although there are some books describing designs of active/passive antenna systems [1-4], the multi-function concept has yet to be fully explored for antennas. by incorporating the dielectric resonator (dr) antenna (dra), the authors have recently demonstrated several multi-function features such as the packaging cover, oscillating load, and filtering device [5-7]. in order to provide a systematic reference to the antenna/microwave researchers and designers, the authors are planning to write a book capturing the multi-function techniques for antennas and microwave components. this book will be divided into five chapters (~250 printed pages), encompassing both the active and passive multi-function antennas and components for microwave systems.