Today, the state of the art antenna technology allows the use of different types and models of antennas, depending on the area of application considered. The rapid progress in wireless communications requires the development of lightweight, low profile, small size, flush-mounted and wideband multi-frequency planar antennas. This book reviews recent advances in designs of various microstrip patch antenna configurations. Microstrip patch antennas have been widely used in the range of microwave frequencies over the past twenty-five years, and over the past few years, single-patch antennas have been extensively used in various communication systems due to their compactness, economical efficiency, light weight, low profile and conformability to any structure. The main drawback to implementing these antennas in many applications is their limited bandwidth. However, the most important challenge in microstrip antenna design is to increase the bandwidth and gain. Theoretical study of various patch antenna configurations will be carried out in this book. The study is performed by using full wave analysis and analytical techniques for the characterization of these structures. Several techniques are used in this book to achieve multi-band performances such as multilayer stacked patches, multiple patches and insertion of slots of different shapes and sizes in the patch antennas. In addition, some novel patch antenna designs for modern applications are given, and some challenges of patch antenna designs are addressed. This book is divided into seven chapters and presents new research in this dynamic field.