Microwave hologram by photoengraving

The photoetching technique was applied to the construction of a microwave hologram. The 34.26-GHz microwave field was mapped by Polaroid film and copied on a printed circuit board. The printed circuit board was illuminated by the same beam as used in the formation of the original hologram. The real image was focused onto liquid crystal film for visualization. A comparison was made between the reconstructed image of the binary microwave hologram and that of the photoetched plate. The photoetched board which can produce the halftone transmission of the microwave beam was shown to be a satisfactory means of making microwave holograms.