wifi2.4GHz + wifi5.8GHz system specicfication

I am looking to build a wifi system i.e an antenna , amplifier system at wifi frequencies. I am not sure what kind of specifications are critical like input power from the antenna into the amplifer, o/p power to the antenna. What parameters are critical while building this system. Any suggestions would be greatly appreciated.

Contact Broadcom and get one of their single chip WiFi transceivers and you're done.

Dave