First Findout the Canvas.Left and Canvas.Top properties of ellipse which we r gonna move.
int x=0;
timer_tick(sender,e)
{
double left=Canvas.getLeft(ellipse1);
double top=Canvas.getTop(ellipse1);

 double a = Math.Cos((angle - x) * (Math.PI / 180));
                    x = x + 5;
                    ellipse1.SetValue(Canvas.LeftProperty, left + 20);
                    ellipse1.SetValue(Canvas.TopProperty, top - (20 * a));
}