I have an Alfa AWUS036NH (2000 milliwatt WiFi device) connected to a USB 2.0 port on a notebook PC. Although the USB 2.0 spec. calls for 500 milliamperes at 5 volts for each USB port, this notebook will only supply 150 milliamperes at 5 volts for each USB port, so I have ordered a powered USB hub which will supply 3000 milliamperes or 3 amperes to it's four USB ports. I expect to see a significant increase in performance. According to searches that I've done on the web, the AWUS036NH input power is 500 - 550 milliamperes at 5 volts which is believable, since this device can output 2000 milliwatt. At 100% efficiency, which isn't going to happen, the input should be 400 milliamperes at 5 volts, so 500 - 550 milliamperes sounds about right.
