Help me to build a DIY antenna that boosts wireless Internet reception

I want to have a go building an antenna to try and boost my wireless internet reception, as i cant find anyone selling them at a reasonable price. The included one is a 3400-3600 Mhz 5dbi gain patch, but im hoping to put something together that has a better gain.

Are there any software packages for designing antennas that would be useful for a novice like me? Does anyone know where i might be able to find the design for such an antenna?

I have been looking around for info on this, but all i seem to come up with on the DIY side of things are 2400 Mhz wifi yagi antennas. can someone recommend a book that would help me modifying one of these designs?

Please excuse my ignorance on all this, i only normally deal with digital electronics, so im a bit out of my depth here.

The easiest one would be a parabolic reflector with your described antenna at the focus pointed towards the reflector.

microstrip antenna maybe achieve your goal!