The minimum wavelength of a microwave depends on the specific definition or classification being used. In general, microwaves are considered to be electromagnetic waves with wavelengths ranging from approximately 1 millimeter (mm) to 1 meter (m), corresponding to frequencies between 300 megahertz (MHz) and 300 gigahertz (GHz).
If we take the lower end of this range, the minimum wavelength of a microwave would be around 1 millimeter (mm), which corresponds to a frequency of 300 gigahertz (GHz). However, it's important to note that this is a general range, and different sources may use slightly different values to define the boundaries of the microwave region of the electromagnetic spectrum.