Most passive antennas that improve range are directional but that can be an advantage. I saw a really cute trick with a biquad patch antenna. The way a biquad works the signal is a cone about 90 degrees wide emanating straight out from the front of the antenna. The guy put the antenna in the peak of his roof and pointed it straight down. This way the areas of his house where he would want to use the wi-fi (office, living room, front porch) were covered but it was impossible for the neighbours or any passerby on the street to get enough signal to connect.
If you are going to experiment with antennas be careful about power output. There are strict laws about that. If you install a permanent installation that breaks them you may wind up with a visit from the feds.
__________________ He either fears his fate too much, or his deserts are small, that dares not put it to the touch, to gain or lose it all.
- James Graham