In this paper, we proposed Q-SAND (Quick Sectored-Antenna Neighbor Discovery), a neighbor discovery protocol for wireless networks with sectored antennas which enhances the state-of-the-art SAND protocol. Both SAND and Q-SAND protocols were successfully implemented in Contiki, an open source operating system for Wireless Sensor Networks and the Internet of Things, and extensively tested using Cooja simulator for Tmote Sky nodes with 6-sectored antennas. The neighbor discovery times were analyzed and analytical expressions were found showing that the time needed to discover all sensor nodes of a network is proportional to the number of nodes in that network. The proposed enhancements to SAND protocol speed up the discovery process up to K times per node, being K the number of sectors of the sectored antenna. Our experiments based on simulations show that for a 6-sectored antenna the time is reduced by 4 times per node, with a greater impact in time and power consumption in networks of increasing size. The Q-SAND protocol performance has been verified through simulations for different network topologies and sizes and compared with that of SAND.