wifi.log: what's going on?
1.What are "Scan requests":
The scan requests are the system (the airportd dameon) scanning for available WiFi networks.
The precedure maybe runs like this:


Application send a request to airportd
ScanManager receive broadcast scan request from airportd
ScanManager initialize scan
ScanManager return scan results to airportd


("scan cache updated" will show due to a fresh scan result)

2.Possible Cause:


Shown in the picture,Google Chrome may trigger the scan frequently.Close chrome and QUIT chrome should stop this "annoying" loop.

3.Link quality:
Since it doesn't change a lot in the log,No need to worry about if your battery life does not seem to be suffering