This paper is intended for teachers and students dealing with antenna engineering. Graphical tools have historically been used for illustrating many basic features of radiation patterns, such as the position and number of secondary lobes, null angles, and beam steering. This paper describes one of these graphical devices, which has been successfully used by the author as a classroom demonstration in many undergraduate antenna courses. In addition, this traditional demonstration is also discussed in the context of modern computer software, such as MATLAB.