Enhanced Microwave Absorption of Quartic Layered Epoxy-Mwcnt Composite for Radar Applications

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Microwave absorbers present a wide range of applications in radar and telecommunications. To improve the microwave absorption characteristics of radar-absorbing structures (RASs), magnetic and dielectric materials are blended in different proportions because the impedance mismatch of dielectric materials, resulting from poor permeability, can be eliminated by a combination with magnetic loss fillers. Herein, E-glass/epoxy composites were prepared by blending multi-walled carbon nanotubes (MWCNTs) with Ni 0.5 Zn 0.5 Fe 2 O 4 (NZF) nanopowder to enhance the composites' microwave absorption. Nanocomposite laminates with different filler contents were fabricated by a simple and low-cost process of in situ polymerisation. The dielectric characteristics were estimated in the X-band, and possible loss mechanisms were studied. A two-layered RAS exhibited a reflection loss of −16 dB for a bandwidth of 2.2 GHz with a matching thickness of 3 mm. The resulting mechanical and thermal properties suggest that the proposed MWCNTs/NZF composite exhibiting good microwave absorption properties can be used in high-performance RASs.

Section: Reflection Loss By Two-layered Mwcnts/nzf Compositesmentioning

confidence: 99%

X-band radar-absorbing structures based on MWCNTs/NiZn ferrite nanocomposites

Nagasree¹,

Ramji

Naidu

et al. 2020

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“…where Z i is the input impedance at the first air-absorbing interface and Z a is the free-space impedance. For each layer i, the impedance of the input wave of the multilayered structure backed by a perfect electrical conductor (PEC) is expressed as [48,49]…”

Section: Reflection Loss Of Double-layered Radarabsorbing Structuresmentioning

confidence: 99%

Synthesis of Ni_0.5Zn_0.5Fe₂O₄-reinforced E-glass/epoxy nanocomposites for radar-absorbing structures

Nagasree¹,

Ramji

Subramanyam

et al. 2020

The development of new radar-absorbing structures (RASs) with strong microwave absorption, fine thickness and adequate structural performance is imperative. Herein, nanocrystalline Ni 0.5 Zn 0.5 Fe 2 O 4 was synthesised by a facile and effective sol-gel autocombustion technique. The structural and magnetic properties of ferrite were determined by various characterisation techniques, and E-glass/epoxy-based nanocomposites with different weight percentages of ferrite were fabricated by in-situ polymerisation. Further, electromagnetic properties were investigated to elucidate the possible absorption mechanism of the fabricated structures. The 4-mm-thick double-layered E-glass/epoxy/nickel-zinc ferrite composites exhibited reflection loss (RL) of <−10 dB for a bandwidth of 2.4 GHz and a maximum RL of −33 dB at 9.6 GHz. This performance was attributed to the larger magnetic loss and sufficient matching of electromagnetic parameters. This study provides a unique insight into the utilisation of Ni 0.5 Zn 0.5 Fe 2 O 4 for producing lightweight and relatively thin RASs in the X-band at a low cost.

“…Among the polymer-based composite materials, extensive research has been conducted on epoxy resins owing to their superior adhesion, heat and chemical resistances, mechanical properties, and remarkable electrical insulating properties. Moreover, epoxy-based composite materials with different magnetic and dielectric fillers have been investigated with respect to radar absorption [3, 5, 7, 8, 11-19]. Epoxy-based MWCNT composites exhibited a RL of – 5 dB in X-band frequency [11].…”

Section: Introductionmentioning

confidence: 99%

Microwave-absorption characteristics of polyaniline-coated multi-walled carbon nanotube composites

Haritha¹,

Ramji²,

Subrahmanyam

et al. 2020

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In this study, the microwave-absorption characteristics of multi-layered radar-absorbing structures (RASs) were investigated. Electrical-grade glass (e-glass)/epoxy composites containing modified multi-walled carbon nanotubes (MWCNTs) were fabricated. The poly aniline (PANI) coated MWCNTs was obtained by in-situ polymerisation of aniline in the presence of MWCNTs. The PANI-coated MWCNTs (PCNTs) were then used as reinforcements in the polymer matrix, and their morphologies, microstructures, thermal stabilities, and microwave-absorbing properties were investigated. The complex permittivity and permeability of the composites were measured and found to have increased with increasing filler concentration. Microwave absorbing properties were analysed via waveguide measurement. The three-layered RASs reinforced with PCNTs having a thickness of 4 mm exhibited a RL of -5 dB over the entire X-band and a reflection peak of -24.53 dB at 10.0 GHz. Hence, the epoxy/PCNTs composites are suitable for use in microwave-absorption applications.