[header] How to design a simple antenna [title] Find out what frequency you want (for wi-fi you are using 2.45ghz = 2 , 450 , 000 , 000hz). [step] This is needed because this determines the length of your antenna. [title] Get a good conductor. 
[step] For the example we can use a copper wire and a piece of copper plating. Also you will need a co-axial cable (75 ohm is better than 50 ohm, for wi-fi 50 ohm is better than 75 ohm).