A motion sensing method and apparatus includes a housing enclosing a microwave motion sensor including an antenna, and a security system. The antenna may be a patch antenna which includes microwave radiating elements for transmitting and receiving a microwave signal for sensing motion. A reflector is attached to the housing and positioned above the antenna for downward shaping of the microwave signal. The microwave radiating elements together with the reflector provide a radiation pattern where a main beam is transmitted in a direction orthogonal to a surface of the antenna and a sided lobe is transmitted downward in amplitude below the microwave motion sensor. An alarm circuit indicates when the microwave sensor detects motion in armed mode, and a masking circuit indicates when the microwave sensor detects motion in a mask zone when the security system is unarmed. A second sensor may be positioned beneath the microwave motion sensor.