I did a little fooling around in another context with high gain external antennas and learned two things:
- the cable to the antenna from the radio needs to be very large or very short (like, a matter of inches. The attenuation of the signal was very high.
- If you use a usb dongle, on the other hand, the cable can be longer because you are bringing the radio to the antenna.
Whether with a cantenna or a 3 foot long high db Tv-type antenna, I wasn’t doing much better than an internal laptop did.