A Compact and Broadband Microstrip Patch Antenna Based on the Flexible Magnetic Dielectric Material

A flexible microstrip patch antenna using a dielectric-magnetic composite substrate of
$\text{Ni}_{.5}\text{Zn}_{0.5}\text{Fe}2\mathrm{O}_{4}$
(NZO)/rubber is proposed. The ferrite NZO reduces the antenna size and increases the bandwidth, while the rubber lowers the losses and enhances the flexibility. The substrate has suitable dielectric and magnetic properties in the S and C bands (2-8GHz), with a dielectric constant of 3.5-4.0, a permeability of 1.1-1.7, and a loss tangent of about 0.1. We fabricated a circular microstrip patch antenna (diameter 50 mm, thickness 5 mm, patch size 31.5mm) with an operating frequency of 2.227GHz and a bandwidth of 290 MHz (12.7
^%
), which matches well with the simulation results. This work shows that dielectric-magnetic substrates can enable miniaturization and broadband in antenna design.