High Res Wifi Signal Mapping

I've also achieved substantial improvement with simple parabolic shaped, ~40 cm wide aluminum foil constructions, but there always seemed a bit luck involved and it needed some tweaking. Not sure whether the foil mainly acted as shielding that reduces the noise floor from other directions. I've read in other forums that fiddling with aluminum foil is mostly luck because additional reflective surfaces also introduce interferrence patterns unless they are precisely aligned. Even without aluminum foil it often helps to move either receiver or sender by fractions of 12.5 cm (the wavelength of 2.4 Ghz radiation) or of 6.0 cm (in case of 5 Ghz) because the space is basically riddled with interference patterns: [this video]