Magnetic, dielectric and structural properties of CoxZn(0.90-x)Al0.10Fe2O4 synthesized by sol–gel method with application as flexible microwave substrates for microstrip patch antenna

Abstract

In this study, novel flexible microwave substrates based on CoxZn(0.90-x)Al0.10Fe2O4 nanopowder having an average grain size of 20 nm–26 nm were prepared using the sol–gel synthesis technique for microstrip patch antenna applications. At first there are three different molecular composition were chosen having the chemical formula of CoxZn(0.90-x)Al0.10Fe2O4 and specified as Co20, Co40 and Co60 for x = 20%, x = 40% and x = 60% respectively. Then the synthesized ferrites materials were characterized with XRD, FESEM, and VSM analysis, and single-phase spinel with high crystallinity were revealed. Besides, the dielectric and magnetic properties of the proposed Co–Zn ferrites samples were investigated for the affirmations of microwave applications. The values of dielectric constant εr and loss tangent (Tδ) are determined using dielectric assessment kit, and the obtained values are ranges from 3.5 to 4.5 for εr and 0.002 to 0.006 for Tδ for Co20, Co40, and Co60 respectively. Also, the magnetic permeability μr and magnetic loss tangent (Tδm) values are determined to form the predetermined scattering parameters S11 and S21 obtained from rectangular substrate pellets and the obtained values of μr and Tδm are ranges from 0.90 to 1.00 and 0.003 to 0.007 respectively. Finally, a modified diamond-shaped microstrip patch antenna is designed and fabricated on the proposed flexible substrates obtained from the synthesized Co–Zn ferrites nanopowders by mixing with PVA binder to validate their application in the S-band of microwave regime. The finite element method based computer simulation technology software is used to design the proposed microstrip patch antenna; furthermore, the simulated prototype is fabricated, and their reflections coefficients are measured for verification. The simulated and measured result of the proposed flexible antennas exhibits a maximum of 3 GHz bandwidth in between 2.5 and 5.5 GHz. Thus, the proposed materials offers tunable dielectric and magnetic properties with soft magnetic behaviors and easy to use where arbitrarily electromagnetic values are required. Moreover, these materilas also can be played significant role in flexible microwave field as low cost flexible substrates for compact flexible antennas, metamaterials, absorbers, and sensors applications etc.