Far-field radiation pattern control has strong potential in smart antennas, wireless communications and radar. Typical planned applications include multipath fading and interference mitigation, data rate and coverage enhancement, etc. For implementing these functionalities, either switch beam or reconfigurable Half-Power Beam-Width (HPBW) antennas are required. In particular, short range and “Stop and Go” radars are deployed by car industry (Wenger, 2005) and operate in millimeter wave frequency bands. Multi-beam antennas have been studied extensively and realized using diverse techniques. Butler (Butler & Lowe, 1961) and Blass (Blass, 1960) matrices are complex feed networks composed of couplers and phase shifters which provide phase difference between radiating elements to steer a beam in a given direction. Rotman lens (Rotman & Turner, 1963), (Schulwitz & Mortazawi, 2006) is a quasi-optical system based on a cavity limited by two arcs. Inputs and outputs are placed along the two arcs and phase difference between the output ports is achieved by microwave propagation through the cavity. Micro-Electro-Mechanical Systems (MEMS) have been employed either to mechanically orientate an array (Baek et al., 2003) or to switch between two antennas having a different beam angle (Cetiner et al., 2003). Lens array (Popovic & Popovic, 2002) and dielectric lens (Wu et al., 2001) are other interesting concepts used to design multi-beam antennas by moving the feed at the back of the lens. In this chapter, the authors present different antenna concepts to obtain reconfigurable radiation pattern capability in millimeter waves.  First, multibeam antennas are demonstrated based on Butler matrices at 24 and 60 GHz. Passive and active designs are considered and manufactured prototypes are presented to show radiation patterns and gain results.  Furthermore, reconfigurable Half Power BeamWidth (HPBW) antennas are shown. The objective is to modify the directivity of an array by changing the number of fed patches. Passive and active prototypes have been fabricated to prove the reconfigurability concept at 24 GHz.  Finally, a new technique is presented to shape the radiation pattern of an antenna to achieve directive or sectorial beams. In this case, the antenna design is based on an inhomogeneous lens (Maxwell Fish-Eye lens) fed by several sources. 7