How to make matcha tea without matcha whisk?
I have had a lot of success getting matcha whipped into a nice froth (and getting rid of the little tea lumps) using a small blender, like a Magic Bullet. I just put the warm water and matcha powder into the blender, pulse it a few times, then blend it continuously for about 20 seconds. 

If you don't mind putting in more elbow grease, a balloon whisk can work just as well for doing it by hand.