Magneto-dielectric properties of PDMS–magnetite composite as a candidate for compact microstrip antennas in the C-band 5G frequency

As one of the promising materials in antenna miniaturization, magneto-dielectric (MD) composites were synthesized from polydimethylsiloxane (PDMS) and magnetite (Fe₃O₄). MD materials attract much attention because of their multiple characteristics, including dielectric permittivity and magnetic permeability, while reducing the antenna wavelength. In this paper, MD composites were synthesized using a standard composition process from a 10:1 elastomer base and curing agent mixed with Fe₃O₄ nanopowder. To determine the effect on the material and electrical characteristics, Fe₃O₄ with weight ratios (x) of 10%, 20%, and 40% was added to the mixture. Several analyses were carried out, including XRD, SEM, VSM, and electromagnetic (EM) characterization, to determine the permittivity, permeability, and losses of samples at the microwave frequency. Based on the measurement, a relative permittivity of 2.54 and permeability of 2.67 were achieved from the MD composite with x = 40%, making it great for antenna miniaturization when used as an antenna substrate. Moreover, based on the simulation, the antenna with the proposed MD substrate has an acceptable performance at 3.5 GHz with a fractional bandwidth of 50.76%, directivity of 4.91 dBi, and dimensions 85.94% smaller than those of the antenna with the dielectric-only substrate.