In this study, the hybrid composite structure having RCS reduction performance to apply for the radome of aircraft was presented. In order to achieve a stable performance for oblique incidence such as polarization, and angle of incidence, the design parameters and evaluation factors were analyzed based on equivalent circuit model analysis.
Firstly, the hybrid composite structure having frequency selective transmission characteristics with stable performance for oblique incidence were investigated. The design procedure was optimized through the processes such as design, fabrication, measurement, and redesign of FSS layer-embedded hybrid composite structure having complex wall construction of multilayered dielectric medium, and presented. For the validation of the feasibility of this design procedure, the fabrication and measurement of a prototype model of hybrid composite structure have been conducted, and the proposed design has confirmed to have stable performance for TE, TM polarization and changes of angle of incidence 0-70°.
Secondly, the design parameters were investigated to implementing the frequency selective transmission/absorption characteristics of the hybrid composite structure to obtaining high adaptability not only mono-static, but also multi-static radar systems. In order to solve the limitations and improving the performance of impractical previous studies based on lumped elements, the Printed Electronics and Resistor-Conductor Material (RCM) technology-based design method was considered, and compared through the fabrication and measurement. The Printed Electronics technology based design have absorption bandwidth (Abs.≥90%) about 4.13GHz and resonance frequency deviation below 230MHz (Maximum insertion loss of 1.5dB) in the variation of the incidence angle of 0-45°. In case of RCM technology based design was confirmed to have absorption bandwidth about 2.4GHz (Abs.≥90%) and resonance frequency deviation below 70MHz (Maximum insertion loss of 1.6dB) in the variation of the incidence angle of 0-40°.
Each two-type design has been fabricated, and which was verified through the measurement of transmission, reflection and absorption characteristics. The measured results were confirmed to have good agreement with calculation.
The study on the design of hybrid composite structure design is expected to contribute to the development of stealth technology that requires high adaptability to various radar systems for improving the survivability in modern warfare.