Design and Manufacturing\nof a Hexapattern Frequency\nSelective Surface Absorber for Aerospace Stealth Application

Integrated frequency selective surface (IFSS) absorbers\nwith larger\nbandwidth, effective reflection loss, polarization-insensitive characteristics,\nangular stability with compact/thin design, and ease of fabrication\nhave captivated significant importance in stealth technology. Herein,\nwe report on an IFSS absorber that has been designed, simulated, and\nimplemented for manufacturing to achieve effective stealth properties.\nInitially, frequency selective surface (FSS) layers have been designed\nthat comprise a closed centroid honeycomb structure surrounded with\nfour annular hexagonal rings, splitted, alternatively, and enveloped\nwith four L-shaped elements. The simulated pattern has been optimized\non glass fabric for reflection loss (RC, dB) at a thickness of ∼0.1 mm by choosing sheet resistance\nof pattern 110 Ω/□. A FSS layer combined with interlayer\nlossy dielectric laminates (1.8 mm) and a carbon-fabric-reinforced-plastic\nground has been simulated as an IFSS absorber. The performance of RC, in normal and angular configuration (0–60°),\nunder transvers an electric/magnetic mode of polarization, including\nanalysis of the displacement current, volume power loss distribution,\nand complex admittance has been carried on IFSS. Subsequently, the\nproposed absorber has been fabricated using customized carbon-based\nresistive ink imprinted on glass fabric by mask lithography compounded\nwith laminates (a carbon black powder/epoxy composite) and ground.\nTheir manufacturing details, including free space and anechoic chamber RC measurements, have been presented. The simulated\nand experimental RC performances of the\nabsorber are found to be in good agreement, possessing minimal 10\ndB reflection loss (90% absorption) with a sample thickness of 1.9\nmm (0.05λL, where λL corresponds\nto a lower operating frequency), covering 76% fractional bandwidth\nin X and Ku bands. The proposed design architecture of the IFSS is\nideally suitable for aerospace stealth platforms.