This book investigates in detail the generalized principle of the pattern multiplication (GPPM) and its application to new phased array with high performances. It introduces the generalized element factor (GEF) to small aperture with multi-modes. Based on the GEF, the GPPM can be used to construct the wide-angle scanning array with the dual-port phase mode antenna. Further, a dual-port phase mode SSPPs antenna is proposed to scan in 3D free space. It is extended to two kinds of 1D arrays with 4 elements; both of them perform good 3D scanning with high gain and large range, which will improve future radar design and wireless communication. This book proposes a new method to develop the potentialities of the GPPM and the new phase array. And the readers can study the method or ideas of the GEF, GPPM, even graft the methods to new phase mode antenna and array. It is intended for undergraduate and graduate students who are interested in new phase mode antenna and array technology, researchers investigating high-performance antenna, and antenna design engineers working on phase array applications.