How do you make an overhead camera?

I want to have the player's camera right above them when they move around but the CoordinateFrame part in the while statement prevents movement. Is there a workaround or am I doing it totally wrong?

wait(1)
Cam = game.Workspace.CurrentCamera
h = script.Parent.Parent.Character.Head
Cam.CameraType = "Follow"
Cam.CameraSubject = h
while true do
    Cam.CoordinateFrame = CFrame.new(h.CFrame.x, h.CFrame.y + 20, h.CFrame.z)
    wait()
end