Advancements in directional antennas or adaptive antenna arrays (AAA) provide potential benefits in solving various problems in wireless sensor network (WSN). Our earlier studies have investigated feasibility of applying smart antennas for task dissemination and localization purposes , . Network connectivity or connectivity probability is also an important issue for smart antenna capable WSN as it relies on received "response" packets from the sensor nodes via routing beam. In this study, we analyze the connectivity of smart antenna (SA) capable wireless sensor networks by modeling the WSN network as a random graph and determine connectivity probability (CP) between the sensor nodes. Analytical and simulation results are presented for connectivity probability and number of sensor nodes under different network conditions such as routing beamwidth, node density, and node transmission range. The results provide the practical values for connectivity probability to design smart antenna based WSN localization and shows that the wider beamwidth and/or higher node density in the routing region provides higher CP level.