Abstract.
Electromagnetic field analysis was performed for the quiet zone of a tapered
anechoic chamber with a lens. Some parameters of the lens like focus distance
and diameter were optimized. The numerical calculations were performed by the
method of integral equations in FEKO program. Using cluster of ITAE RAS allowed
carrying out simulation of the field distribution in the quite zone of the
tapered chamber in frequency range of 0.4 – 1 GHz.
Matching layers are used for
improving lens properties. The matching pursues two goals: firstly, it reduces
reflections inside the lens and, secondly, it provides a smother “lens – air”
transition, thus reducing diffraction effects at the edges. Both
the lens and the matching layer are made of a new lightweight composite
material with unchangeable low dielectric permittivity. The diameter of the
lens is 4.5 meters.
The matching layer was developed,
which makes it possible to reduce the non-uniformity distribution of the field
in the quiet zone of the chamber by 0.5-1 dB within the frequency range of
0.4-1.0 GHz compared with the chamber with the lens without a matching layer.
It is shown that the field amplitude non-uniformity may become less than 2.2 dB
with the lens coated by a matching layer within the frequency range of 0.4 – 1
GHz and with the phase distribution non-uniformity not exceeding 15 degrees.
It is sufficient to make the
matching layer only on a plane surface of the lens. This matching layer ensures
the non-uniformity field distribution is the same as a large lens of 4.5 meters
in diameter.
Keywords:
tapered anechoic chamber, dielectric lens, matching layer, method of moments,
FEKO.
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