The microwave spectrum ranges from several hundred MHz to dozens of GHz which were allocated originally by the National Radio Regulatory Commission in China.

The man-made sort can do things like transmit music or heat food in a microwave. At the low end of the spectrum are the frequencies used for things like television and mobile phones.

This is no small thing; the standard for Wi-Fi was developed on unlicensed spectrum that had been considered "junk band", cluttered with low-intensity signals from microwave ovens and baby monitors.