I bought this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 to extend the range of my laptop's wifi, but not only can I not get it to work under Linux, when I use it with Windows I don't get access to any more networks or any stronger signals than when using my laptop's internal wifi card. (I removed the internal card to make sure I was actually using the USB antenna.) It came with a small CD with Windows/Mac/Linux drivers on it, but when I ran the Linux installer, it gave me the error: "Compile make driver error: 2; Please check error Mesg". I can't find a log file anywhere. When I booted into Windows, it was recognized right away and I was able to connect to my home wifi, but I only saw the usual additional networks.

Is there something special I need to do, or is this a crappy antenna? If the latter, what would be a good, long-range antenna to buy?

What you have is a wifi adapter with a large antenna. That means you can transmit farther, but receive might be closer to the same as with the internal card. Since the laptop "receives" information on the other access points around you, you may not see more of them.

So what kind of device would I need to connect to wifi networks farther away?

a cantenna maybe?
i.e. a directional passive antenna, self-made with a tin can.
but that would require a possibility to connect it to your wifi device - certainly not via usb.
my old motherboard had an antenna plug for its internal wifi.

Thanks for the info! I'll definitely have to look into that.