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Multicast transmission plays a vital role in reducing wireless data traffic. However, the conventional multicast beamformer design mainly relied on suboptimal solutions found by numerical solvers which failed to provide analytic design insights, due to the analytic intractability of the multicast beamformer design problem. In this paper, we explore a rank-one multicast beamformer design for a single group multicasting scenario and derive a closed-form solution to help how the channel parameters affect the beam direction and the achieved SNR. To this end, we first revisit the Karush-Kuhn-Tucker (KKT) necessary condition of the single group multicasting problem. Then, we derive a closed-form solution for a multicast beamformer, which satisfies KKT necessary conditions, for given active constraints. Finally, we select the best beamformer among the ones from different active constraints. It is shown that the proposed …