Chapter 22 - Design of electromagnetic absorbers based on green nanomaterials

Abstract

The process of electromagnetic (EM) suppression significantly contributes for the eradication of adverse EM interference (EMI), providing measures for reducing the radiated noise, design of anechoic chamber facilitating EMI measurement making the electromagnetic environment compatible with high-frequency electronic devices. The EM suppression is implemented by designing efficient and wideband EM absorbers. In military applications, particularly in stealth technology, for concealment of an object from radar detection, EM absorber is required to absorb electromagnetic waves mainly lying in the microwave frequency band. In case of antenna arrays, placing an absorbing device between array elements is able to reduce the mutual coupling effect thus improving array gain, directivity subsequently suppressing the adjacent channel interference with enhanced bit error rate (BER) of an array. Although researchers have proposed various programming-based algorithms and codes to reduce the intercoupling effect, these codes are very complex and time-consuming. Moreover, to implement computer codes, extra firmware is required. Application of absorbers on antenna array can effectively reduce side-lobe levels along with preventing the EM propagation at the rear surface of array hence increasing front to back ratio of an array. Due to numerous absorber applications in contemporary wireless communication, scientists are continuously exploring and engineering various materials and their geometrical shapes for better absorber designs which would be effectively incorporated with compact and mobile electronic gadgets to eliminate EM pollution and interferences, hence enhancing the performance of electronic devices. Therefore, the different absorbing materials are chronologically investigated in this chapter with main focus on nanomaterial and nanocomposites which proves the best candidates for designing thin, lightweight, transparent and frequency tunable absorber to meet out the future challenges like mobility, gadget compactness and speed. Further, some state of art two-dimensional materials has also been explored in this chapter which would probably replace the existing absorbers in the near future.