This letter presents a novel microstrip patch antenna operating in the Ka band (26.5GHz-40GHz) with pattern reconfigurable characteristic. The antenna is provided with one circle patch, two arc patches and four parasitic rectangular patches. The centre patch is connected with the arc patch by a RF MEMS (microelectromechanical systems for RF circuits) switch. The beam can scan in the E-plane by switching the states of the antenna, which is implemented by changing the states of the switches installed in the gap between the patches. Different states of the antenna have different radiation patterns. The two states share the same operating band of 35.6-37.9GHz with the centre frequency of 36.6GHz and their maximum radiation directions are -38° and +37° respectively. The antenna can be applied in radar, satellite, security communications, etc.