I haven't seen any antenna usb wireless adapters. But if you search google, you will find plenty of cable extension and antennae for wireless access points and routers that may work.
I've used a wireless lan adapter on campus. It can easily pick up a signal without any special antenna while driving. The usb adapter was in the cargo area of my SUV under the tonneau cover. It may be easier/better to add the antenna to the router/access pt in the house.