This is last series from Nonlinear Deformer series. Wave deformer hardly suited for making animation expanding ring of ripple. To apply wave I recommend that you to apply high resolution object. Wave has some attributes, that is:

   1. Envelope
   2. Amplitude: determines amount of wave
   3. Wavelength: determines number of frequencies wave
   4. Offset: determines position of wave
   5. Dropoff: determines position of wave handle
   6. Dropoff Position: determines how far effect from dropoff
   7. Min Radius: determines where wave is started
   8. Max Radius: determines where wave is end

Click to see tutorial