In rescue robot research, wireless LANs have been commonly used as the communication system for its cost-effectiveness and high data rate. However, it is known that receive signal strength of wireless LAN using omnidirectional antenna degrades in the case there is a difference in height between the sender and the receiver such as in the stairs. To resolve this problem, we study basic performance of mobile robot communication using electronically steerable directional antenna called "ESPAR antenna". The experimental results show that using an ESPAR antenna improves received power strength in the communication especially for outdoor environments.
