A few points to consider -
- "forget those longer so called high gain antenna's they mostly dont work that well" What you are creating is exactly that - a high gain antenna. Antenna's do exactly what they are designed to do. The problem is typically installers who do not understand how RF technology works, and expect to be able to tow the QEII using a rubber dinghy and oars...
- DIY antennas are only cheap, if your time is worthless.
- Home made antenna's are actually illegal in many jurisdictions (ever wondered why so many AP's have different connectors, it is a hangover from even tougher regulations where only antennas designed SPECIFICALLY for a given AP were legal.)
- This parabolic template creates a fairly directional antenna (25 Elevation, 35 Azimuth), if you then point this at your friends flat, you will definately impair performance for the rest of the household.