Design and development of cheap and eco-friendly microwave absorber are one of the challenging and interesting topics for the scientific community nowadays. This paper proposes the design and fabrication of corn husk-based low cost, light-weight, and flexible microwave absorber treated as a promising eco-friendly microwave absorber. In this work, an extensive study on microwave absorption efficiency of corn husk at different thicknesses is performed in the frequency range of 1–20 GHz. The absorber at 5.21 mm thickness possesses a return loss (RL) of −32.72247 dB at 2.255 GHz. The measured RL values agree well with simulated ones, indicating the utility of proposed absorber for various practical microwave absorption applications.

A low-temperature synthesis method for Mn3O4/graphene is described in this research. Adjusting the reaction time and temperature allows control over the phase and morphology of the synthesized manganese oxide, and therefore the microwave absorbing properties. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and vector network analysis are used to characterize the phase, morphology, and electromagnetic properties. The results reveal that long reaction time can increase the particle size and high temperature can destroy the initial structure of graphene both of which have negative impact on the microwave absorbing properties. The Mn3O4–graphene composite synthesized in 140 °C for 4 h shows a maximum reflection loss (RL) reaching −20 dB at 14.4 GHz with absorber thickness of 2 mm, as well as an effective absorption bandwidth of more than 5 dB corresponding to RL below −10 dB.

Polyaniline (PANI)–PbTiO3 composites were prepared by using different inorganic and organic acids by in situ polymerization technique using sodium dodecyl benzene sulfonic acid as a surfactant. The structural analysis was studied by using x-ray diffraction, and it was found that PANI is amorphous in nature. The scanning electron microscopy studies reveal that they are agglomerated and irregular, and size of these grains increase by increasing the amount of PANI with different organic and inorganic acids. The real part of complex permittivity (εʹ) and imaginary part of complex permittivity (εʹʹ) and the real part of the permeability (μ′) are studied at X-band frequency where (εʹ) and (εʹʹ) decreas with increase in frequencies, whereas μ′ increases with increase in X-band frequency and exhibits a maximum value of 0.87 at the resonance frequency of 9–11 GHz of 30 wt% PbTiO3 in PANI matrix. Reflection loss peak of 30 wt% of PANI–PbTiO3 composites is 28.6 dB at 10.8 GHz, which may be attributed to the maximum reflection of the microwave power for the particular doping concentration.