Whats wrong with my wifi signal?

i have an iphone 5 and i was able to join my wifi network but even if im close it has really low signal and it randomly disconnects then i have to turn it off and on again and its getting annoying. whenever i use my ipad or an iphone 4 that never happens and i literally having a good signal in places my phone has the weakest signal. is it because its an iphone 5? or why does this happen? is it the update?