What is Far-Field Radiation

This chapter aims to serve as an introduction to the integration process of filters and antennas into a single component, a filtering antenna, or filtenna, which is a topic of rising scientific interest and importance in recent years. As most receiving and transmitting devices nowadays call for a smaller footprint, better power management, and simplification of fabrication, this chapter showcases all the steps the reader must take to have a holistic approach to the integration of the aforementioned two components. Therefore, the fundamental principles of antenna, microstrip line, and filter theories are explored, and they are applied to a proof-of-concept patch filtering antenna operating in the S-Band, and at a frequency suitable for allocation to the 5G communications applications, while notable examples from other authors also demonstrate different ways of tackling this domain.