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Abstract-Nowadays, applications of Frequency Selective Surfaces (FSS) for radar absorbing materials (RAM) are increasing, but it is still a challenge to select a proper FSS for a particular material as well as the dimensions of FSS for optimized absorption. Therefore, in this paper an attempt has been made to optimize the dimensions of FSS for microwave absorbing application using Genetic Algorithm (GA) approach. The considered frequency selective surfaces are composed of conducting patch elements pasted on the ferrite layer. FSS are used for filtration and microwave absorption. In this work, selection and optimization of FSS with radar absorbing material has been done for obtaining the maximum absorption at 8-12 GHz frequency. An equivalent circuit method has been used for the analysis of different FSS, which is further used to design fitness function of GA for optimizing the dimensions of FSS. Eight different available ferrite materials with frequency dependant permittivities and permeabilities have been used as material database. The GA optimization is proposed to select the proper material out of eight available materials with proper dimensions of FSS. The optimized results suggest the material from database and dimensions of FSS. The selected material is then mixed with epoxy and hardener, and coated over the aluminium sheet. Thereafter, all five FSS were fabricated on ferrite coated Al sheets using photolithographic method followed by wet etching. The absorption was measured for all FSS using absorption testing device (ATD) method at X-band. Absorption results showed that significant amount of absorption enhanced with the addition of proper FSS on radar absorbing coating.

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The development of thin microwave absorber coatings that operates for a wide range of frequencies is still a challenging task. This work presents a technique of blending a fractal frequency selective surface (FSS) with single-and double-layer coatings. These coatings are comprised of well-optimized micrometer-sized (80-90 m) and nano-sized (20-30 nm) Ti particles based Fe O (80-100 nm) composites. The main objective of this study is to achieve good absorption with wide bandwidth corresponding to reflection loss (RL) dB for less coating thickness ( 1.5 mm). Waveguide measurements are carried out to obtain the effective complex dielectric permittivity ( ) and effective complex magnetic permeability ( ) values of Fe O -Ti based heterogeneous composites. The measured , , , and values are used for the designing of double-layer composite absorbers, where the suitable composite selection, layer preferences, as well as thickness of layers are optimized using a genetic algorithm. The fractal geometry based FSSs have been designed using an iterated function system, which are embedded with single-and double-layer composite absorbers to examine their effect on absorption. A double-layer composite coating with a Sierpinski gasket fractal FSS shows a strong RL of 35.57 dB at 9.5 GHz with broad bandwidth of 4.2 GHz in the range from 8.2 to 12.4 GHz. The total coating thickness is only 1.4 mm. Findings provide an effective and feasible way to develop thin and broadband absorber coatings for various practical applications. Index Terms-Composite materials, fractals, frequency-selective surfaces (FSSs), microwave absorbing materials (MAMs).

Abstract-Qualitative phytochemical analysis of this plant confirms the presence of various phytochemicals like alkaloids, flavonoids, tannins, terpenoids, saponin, steroids, and proteins, reducing sugars, carbohydrates and cardiac glycosides in its methanolic extracts. This paper deals with the significance of these phytochemicals with respect to the role of these plants in traditional medicinal system. This preliminary study draws attention to the need for further studies of the active principles identified in the reported species for the treatment of many diseases in order to understand their mode of action in controlling diseases.