X-band Holographic Antennas Back Radiation Comparison

It is known that “back” radiation in holographic antenna systems radiation pattern is associated with the choice of a binary approximation of the interference pattern when recording holograms. In this paper, it is shown that this effect can be avoided by using a system of coupled dipoles instead of solid metal in the surface synthesis. The data of both numerical and experimental (in far-field zone for radiation patterns measurements and in near-zone for amplitude distributions) study of X-band flat holographic screens are presented. Numerical peak directivity value for proposed holographic surface topologies is found to be 19.3 dB while for one-layer holographic antenna system based on solid metallization numerical peak directivity value is 16.7 dB. The measured F/B ratio for the proposed design based on coupled dipoles element of two-layer holographic screen at 9.6 GHz is obtained to be -7.65 dB, instead of -2.2 for solid metallization (one-layer design).