how to make wireless device at home

While it is very likely possible for a person to build their own wireless router from scratch, detailed circuit diagrams for such a thing are not widely published and the necessary components would be difficult or impossible to find because commercially produced equipment relies heavily on custom-designed ICs which are made for and distributed by large companies like 3Com/Unisys and others. It is far cheaper and easier to buy a commercially produced router than to try to make your own. Most countries impose a restriction on the aerial power of domestic WiFi equipment so that it has an effective range of up to 30 metres. It is possible (but rarely legal) to increase the range of a device either by using a directional aerial or by amplifying the signal and using a larger aerial. Most such modifications would very likely be illegal and would almost certainly invalidate your warranty. There are many websites which describe in detail how to do this but it would probably be against the Terms of MyLot to give the URLs. I suggest that you use a Search engine to find them. You can increase the range (or, more accurately, change the coverage) of a wireless router by installing a repeater or by using ethernet cable to position the wireless router in a better place in the house.