Garnet mineral reinforced silicone rubber based composites for flexible microwave substrates. (September 2022)

• Record Type: Journal Article
• Authors: Sibi, N.; Ganesanpotti, Subodh
• Is Part Of: Materials research bulletin. Volume 153(2022)
• Publication Date: 2022-09
• Subjects: Rubber composites -- Dielectric properties -- Garnet mineral -- Microwave applications; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2022.111879
• Languages: English
• ISSNs: 0025-5408

Abstract

Highlights: SR/garnet composites possess εr <5 and tanδ <10 −2 at 5 GHz. The dielectric properties are nearly constant with bending cycles. A reasonably high thermal conductivity of 0.46 W/m/K for SR/Garnet composites. A flexible antenna made from the composites shows a RL of −14.7 dB at 6.5 GHz. Abstract: The present study focuses on developing a flexible microwave antenna using garnet mineral [(Fe1.72 Mg0.8 Mn0.01 Ca0.02 ) (Fe0.04 Al2.36 )Si2.93 O12 )] and silicone rubber. Solution mixing technique has been employed to blend garnet and silicone rubber for fabricating composites. AFM analysis shows that the surface roughness of the composites is of the order of 10 −2 μm, so that the conduction loss of the antenna can be minimized. The microstructural analysis ensures uniform distribution of garnet mineral in the rubber matrix. Dielectric studies show silicone rubber/garnet composites have relative permittivity in the range of 3–5 while loss tangent is of the order of 10 −2 . Analysis of thermal properties show that for 50 wt%, the coefficient of thermal expansion is 163 ppm/ °C and thermal conductivity is 0.4 W/m/K. A flexible antenna designed and fabricated using silicone rubber/garnet composite (50 wt%), shows a return loss of -14.7 dB at 6.5 GHz. Graphical abstract: Image, graphical abstract