Ravi Panwar

An efficient use of waste material for development of cost-effective broadband radar wave absorber

Very few literatures are available on the utilization of natural waste composite materials for radar wave absorption. The main objective of this paper was to achieve good absorption with wide bandwidth corresponds to reflection loss (RL) ≤ −10 dB for less absorber layer thickness (≤2.0 mm) for a cost-effective production of radar wave absorber. In this study, mineral dust and beach sand-based waste composite material is critically analyzed for its application as broadband radar wave absorber in the frequency range of 8.2–12.4 GHz. A multilayer approach is applied for obtaining the good absorption, where thickness of different layers is optimized by genetic algorithm. The effective absorption bandwidth for two- and three-layer composite absorber is 3.5 and 2.8 GHz for the optimized thickness 1.9 and 1.8 mm, respectively. The two-layer absorber possesses measured RL of −27.20 dB at 10.8 GHz and for a three-layer absorber, RL reaches up to −32.58 dB at 11.2 GHz. The measured RL values agree quite well with the calculated ones, which show the effectiveness of absorber for various practical EM wave absorption applications.

Design and experimental verification of a thin broadband nanocomposite multilayer microwave absorber using genetic algorithm based approach

The bandwidth-thickness tradeoff of single layer microwave wave absorber has become challenge for researchers. This paper presents experimental results of thin broadband multilayer microwave wave absorbing structures using magnetic ceramic based nano-composites for absorption at X-band. A genetic algorithm (GA) based approach has been used to optimize thickness of different material layers and selection of suitable material to ensure minimum reflection. The parameters optimized through genetic algorithm have been simulated through Ansoft High Frequency structural simulator (HFSS) and experimentally verified through Absorption Testing device (ATD). It has been found that the peak value of reflection loss is −24.53 dB for 1.3 mm absorber layer coating thickness, which shows the effectiveness of absorber for various applications..

Microwave absorption properties of FSS-impacted composites as a broadband microwave absorber

The development of a cost-effective microwave absorber with wide bandwidth corresponding to reflection loss (RL) ≤ −10 dB is still a very challenging task. A sugarcane bagasse-based agricultural waste composite has been analyzed for its elemental contents. The combination of elements is suitable for its possible usage as a cost-effective microwave absorbing material. Therefore, this composite has been subjected to morphological and electromagnetic studies to analyze its microwave absorbing behavior. The frequency dependent complex dielectric permittivity and complex magnetic permeability values were obtained using a transmission/reflection waveguide approach in the X-band. Furthermore, the effect of the Minkowski loop frequency selective surface (FSS) was studied over the absorption capability of the composite. It was found that the application of FSS leads to a reduction in thickness up to 2.9 mm and an enhancement in absorption bandwidth up to 3.6 GHz. The FSS patterned composite shows a remarkable performance with peak RL of −28.4 dB at 10.7 GHz and absorption bandwidth of 3.6 GHz.

Investigation of significantly enhanced electromagnetic wave absorption of hard-soft ferrite- graphene nanocomposite

Hard-soft ferrite nanocomposites have attracted increasing attention of researchers due to its excellent dielectric and magnetic properties. Graphene has evoked extensive interests for its abundant EM properties. In addition, other physical properties like large surface area, low density and high chemical stability results in ideal EM wave absorbing material. Dispersion of graphene particles in to magnetic materials like hard-soft ferrite can improve the absorption effect. Taking full advantage of graphene as well as hard-soft ferrite, they are exploited for EM wave absorbing applications in a systematic manner. The main goal of this study is to achieve wideband absorption (i.e., the frequency range in which reflection loss is less than -10 dB) with less coating thickness.

Fractal frequency selective surface embedded broadband microwave absorber using disassembled waste printed circuit boards

The main aim of this study is to develop an cost effective microwave absorber that can provide wide absorption bandwidth (RL ≤ -10 dB) with less coating thickness (i.e., ≤ 2.0 mm). To achieve this, an electronic waste composite based microwave absorber blended with fractal frequency selective surface (FSS) is presented. The disassembled computer and mobile printed circuit boards (PCBs) based electronic waste composite is prepared by top-down nanofabrication approach. The measured complex dielectric permittivity and complex magnetic permeability values have been used for implementation of a double layer absorber in the range of 8.2 to 12.4 GHz. Further, a double layer absorber loaded with Minkowski fractal geometry based FSS is designed with the help of Ansoft HFSS. The developed absorber possesses a peak reflection loss (RL) value of -30.5 dB at 11.3 GHz for 1.9 mm absorber layer thickness. Such a performance permits the use of absorber for various practical electromagnetic applications in an efficient manner.

Novel optimization method of single square FSS impinged and cascaded radar absorbing composites

It is well known that radar absorbing potentiality of existing magneto-dielectric composites can be significantly enhanced by the application of frequency selective surface (FSS) and cascaded electromagnetic (EM) structures. But the optimization of such complex EM structures and validation of the adopted optimization strategy is still a very challenging task for the researchers. Therefore, in this study, an effective effort has been made for the optimization and the corresponding validation for Single Square FSS (SS-FSS) impinged and cascaded radar wave absorbers using advanced computational EM software’s like FEldberechnung fur Korper mit beliebiger Oberflache – a German acronym (FEKO) and high frequency structure simulator (HFSS). In addition, a critical analysis of dielectric constant (ε′) has been carried out to select the best combination of composites for the development of efficient radar wave absorbers. A comparison between optimized and simulated results have been carried out to examine the effect of advanced EM approaches over reflection loss (RL) characteristics of composite radar absorbing materials (CRAMs). A rapid change in radar absorption properties of composites has been observed after the application of SSFSS and cascading. A SS-FSS impinged composite has been found to provide a wide absorption bandwidth of 3.6 GHz at X-band. A cascaded absorber having layer thickness 1.8 mm provides a peak RL of −42.6 dB at 10.6 GHz with an absorption bandwidth of 2.5 GHz. The strong agreement between mathematical model, HFSS and FEKO results clearly reflects the efficiency of adopted approach for distinct practical EM applications.

Parametric analysis of frequency selective surfaces over radar absorbing nanocrystalline structures

A thin radar wave absorber with wide bandwidth corresponding to reflection loss (RL) ≤ -10.0 dB is still very challenging job for researchers till date. In this paper, design of Frequency Selective Surface (FSS) loaded over single layer absorber is carried out with the help of Ansoft HFSS simulation tool. Copper and cobalt doped barium hexaferrite nanoparticles are synthesized through sol-gel auto combustion route and correspondingly its phase and morphology analysis is carried out using X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM), respectively. The waveguide measurements are performed to measure the complex permittivity and permeability values in the frequency regime of 8.2 to 12.4 GHz. Further, critical analysis of different type of FSS structures has been carried out to study the absorption effect. It has been found that strongest RL value for Minkowski loop with level 2 approaches up to -41.0 dB at 10.3 GHz with wide bandwidth of 3.0 GHz, which shows the effectiveness of absorber for various applications.