To Search Wi FI network

Free application Xirrus Wi-Fi Monitor is a cross-platform Wi-Fi tool that displays available networks on a very cool radar map. More specifically, the app searches for Wi-Fi networks, displays strength, detects rogue access points, and helps you tweak your network for the best signal

For more info

http://lifehacker.com/5054802/xirrus-wi+fi-monitor-detects-wireless-networks