We describe the construction of simple microwave sources of centimeter wavelength with bulk‐effect diodes and accessory equipment for experiments and demonstrations in physical optics. A peculiar advantage of 1‐cm wavelengths over the longer wavelengths is the high directivity of hand‐sized parabolic reflectors. Thus we emphasize Fraunhofer diffraction. The collimator and telescope of a student spectrometer for light are replaced by a collimator and telescope for centimeter waves. We describe the construction of equipment for demonstrations with centimeter wavelengths on an overhead projector.