Abstract. The problem of stabilizing parameters of antennas placed
on a metal platform is actual in connection with the development of
ultra-wideband antenna systems. Due to the diffraction and interference
phenomena on a metal platform there is a substantial violation of radio
parameters of antenna systems: irregularity of radiation patterns,
violation of polarization patterns, etc. Application of broadband radio
absorbing materials (RAM) on the platform considerably diminishes
irregularity of antenna radiation patterns and stabilizes its radio
technical characteristics. In practice such RAM are used because of
influence of difficult complex of environmental factors. Within the
framework of decision of this problem broadband multi-layered RAM of
brand RAN-67 developed by ITAE RAS is presented. RAM RAN-67 is intended
for reduce of reflection coefficient of elements of objects construction
in frequency range from 8 to 18 GHz. Modulus of reflection coefficient
of RAM RAN-67 at normal incidence of electromagnetic waves in this
frequency range makes minus 15 dB no more. In the paper the following
tests are described that exposed the RAM to assess its resistance to
external influencing factors: temperature ageing, thermocycling,
influence of positive and negative temperatures and others. The method
is proposed for measuring the temperature dependence of the reflection
coefficient of flat RAM samples in the wide frequency range from 2 to 24
GHz at normal incidence of electromagnetic waves. As results the
comparative characteristics of radar cross section diagrams, frequency
dependences of reflection coefficient and characteristics of RAM
resistance at opening fracture mode are suggested. It is shown in the
total that RAM RAN-67 has high-level operating reliability. At
development of this RAM the following principle was realized: “adhesive
strength is higher than cohesive”. The observance of this principle
eliminates a possibility of exfoliation of layers by big pieces which
can damage the construction of antenna platform. The high-level radio
absorbing properties of RAM RAN-67 in the frequency range from 8 to 18
GHz in combination with high mechanical characteristics, and also rather
small weight and thickness (about 4 mm), allow to recommend this RAM for
application in ultra-wideband antenna systems.
Key words: radar
absorbing material, reflection coefficient, physical and mechanical properties,
radar cross section diagram.
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