Holographic antennas

The extension of holography to the microwave field, for the solution of problems such as antenna synthesis and construction of visible images of microwave illuminated objects, seems to be promising. In preliminary tests, the possibility of designing an antenna having any mean surface, any feeder, and any given radiation pattern by means of holographic technique, is shown. One of the practical problems which is encountered in microwave holography is the construction of the hologram, which requires the antenna to be synthesized. For this purpose, a series of holograms have been constructed and tested based on different approximations of the interference pattern. Another problem encountered is the presence of unwanted orders. Some preliminary tests on phase holograms show that this difficulty can be overcome simply by suitably varying the thickness of the hologram.