There are bunch of USB Wireless devices that use the Realtek RTL8811AU chipset. Some have an external antenna and some don't. Also as many of these devices come with the driver on a mini cdrom and people don't have cdrom drives on their computer or laptop these days, you'll need to get it from the internet.
Windows does have generic drivers shipped and installed with Windows update Realtek RTL8811AU but from experience these can have some stability issues. So installing the official drivers is always recommended. If you aren't having issues with the device, there is no reason other than security issues for updating the device.