Microwave imaging (MWI) systems are nowadays acquiring an ever-growing importance in numerous application fields, such as non-destructive testing (NDT) in civil and industrial applications, subsurface sensing and ground penetrating radar (GPR) prospection, through-wall imaging (TWI) for security and biomedical imaging. MWI systems use an electromagnetic (EM) radiation to illuminate the structure under test (SUT) and exploit the interaction with it to extract information about its physical and geometrical parameters. MWI sensors are constituted by antennas, which are used to generate the incident radiation and collect the field resulting from the EM interaction with the SUT. This chapter, after a brief introduction to the MWI problem and the configuration of the measurement systems, discusses several typologies of MWI antennas and their applications.