Abstract. A technique is developed for the synthesis of bifocal two-mirror systems
that convert two divergent cylindrical waves into convergent or flat ones. The
technique is based on the well-known approach with setting the initial portion
of the mirrors surface and sequentially finding other areas. The technique
ensures the smoothness of the obtained solution. As an example, we synthesized
two variants of bifocal two-mirror systems with different sets of parameters
and an analysis of their aberrations. Analysis of aberrations showed that the
lens, which forms flat fronts at the output, has a mean-square aberration
5.10-4, and for a lens with symmetrical focal curves it is 3.5.10-3.Using
the finite element method, a numerical study of the scanning characteristics of
a planar bifocal two-mirror antenna was carried out.
A numerical experiment was performed to
confirm the scanning properties of the synthesized two-mirror systems. A
cylindrical two-mirror antenna with a width of 160 mm and a height of 1.7 mm
was located inside a planar metal waveguide of the same height and was excited
by an H- sectorial horn with an input section of 7.2 × 1.7 mm and an output
cross-section of 14 × 1.7 mm at a frequency of 37.5 GHz. The geometry of the
focal curve was obtained by optimization by the criterion of maximum gain. In
this case, the direction of the axis of the horn radiator was also optimized.
Losses in metal were not taken into account in the calculation. The antenna
efficiency is more than 0.8 in the sector of angles ± 25 degrees.
Key words: two-mirror systems, bifocal systems, planar antennas,
aberrations, scanning.
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