Miniaturization of such a microwave-driven clock cannot go below a centimetre or so because the microwave cannot fit into guide structures much smaller than its 3.2-cm wavelength.

• 这种微波驱动的钟不能缩小到厘米见方，因为在比它3.；2厘米波长小得多的导向结构里，微波便不能产生。