Radar absorbing materials and structures (RAM/RAS) are required for a stealth aircraft. In this work, radar absorbing materials based on dielectric and magnetic loss materials was indigenously synthesized. The powders were calcined in the temperature range 1000–1200 °C and milled for 24 h for reduction of particle size. The powders were pressed in the form of rectangular pellets / slabs as per the sample holder dimensions of wave guide measurement system (X, P, and K band). Electromagnetic (EM) characterizations of samples were carried out in the frequency range 8–26 GHz. The composition that showed absorption more than 70% in 8–26 GHz was selected. EM simulations were carried out for optimization of thickness of RAM on CFRP substrates. Accordingly, the selected material was applied on CFRP substrates and their EM performance was evaluated which showed greater than 70% absorption in the frequency range of 8.5–20 GHz. Further, environmental tests such as salt spray, low temperature, high temperature, fluid contamination, rain and sand spray tests of RAM applied CFRP substrate were carried out. It was found that the material remained intact after the tests without delamination, de-bonding, blisters, swelling, etc. Therefore, the developed dielectric and magnetic-based materials can be promising candidate for stealth aircraft applications.