Florin from YouriTronics has taken a video where he shows how to make very simple WiFi signal reflector and this way increase the signal level to one direction. For this he used a soda can cut in half. Probably everybody knows parabolic antennas, and ho do they reflect the signal from the focal point. If the WiFi antenna is placed along can shape the focal point, the signal waves will be directed to one direction. Of course, a soda can isn’t parabolic shape, but this cheap solution gives noticeable results.