Stealth or low observable technology has been one of the most critical requirements for military aviation sector to counter the ever‐advancing target detection technologies worldwide. Among many, Radar, which operates in the broadband spectrum, is one of the principal threats, which measures the radar cross section (RCS) of the aircraft. Hence, researchers are putting immense efforts to develop low RCS materials based on polymer matrix composites (PMCs) called as radar absorbing structures (RAS), to replace highly reflective conventional metallic aircraft structures. Though many researchers have been successful in RAS realization using radar absorbing materials (RAMs) as fillers, this review article reckons the state‐of‐the‐art advanced research on the realization of RAS using a combination of RAMs and multilayered grid devices such as, frequency selective surfaces, circuit analog absorbers, metamaterials, and so on, and their effect on mechanical properties to deliver superior performance RAS for stealth aircrafts. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47241.

Cyanate esters (CEs) are recognized as matrix materials in composites for high-temperature structural applications, owing to their excellent thermal and dimensional stability, resistance to micro-cracks, low moisture absorption, and low dielectric loss. Though the brittle nature of CEs curtails their effective utilization, thermoplastic toughening has paved the way to circumvent their innate brittle attribute by virtue of the resulting two-phase morphology. This Review enumerates detailed deliberation on thermoplastic toughening of CEs and their semi-interpenetrating networks. Further, the effects of various decisive variables like thermoplastic concentration, molecular weight, and curing conditions are also reviewed and disserted in detail. In addition, the mechanical properties of numerous developed CE blends and their toughening mechanism are deliberated to elucidate their substantial engineering applications. This Review renders a detailed contemplation on thermoplastic toughening of CEs, composite fabrication methodology, and their structural integrity for high-temperature applications.

High-temperature capable (T g: 280–290 °C), broadband radar transparent [ε′: 3.3–3.9; ε″: 0.02–0.17; tan δ: 0.01–0.04 and transmission loss: −0.18 to −1.26 dBl in C, X, and Ku bands (5.4–18 GHz)], composites were developed using polyetherimide (PEI)-toughened bisphenol E cyanate ester resin and E glass fabrics through an out-of-autoclave process called resin film infusion at a range of PEI weight fractions via a solvent-free method. Their pronounced increase in impact resistance in terms of mode I interlaminar fracture toughness (G Ic; 50–100%), postimpact residual compressive strength (>85%), and enhanced structural properties such as tensile strength, compressive strength, in-plane shear strength, and interlaminar shear strength compared with control laminates, which later re-corroborated with a structure–property relationship using surface morphology proving that PEI-modified cyanate esters can find extensive applications in impact-resistant composite radomes for high-speed aircrafts.