This video shows you how to draw wifi icon. you can easly create your own vector for free. drawing takes only 3 minutes to draw. so why you still want to search png file.?
drawing includes using cut path at selected anchor points command. The simple and accurate way of drawing.
Just watch this short video.
https://www.youtube.com/watch?v=SQpFxEekEVQ
Wifi icon free vector design in illustrator
