Dual band circular polarized patch antenna using small ferrite disks

A novel dual band circular polarization microstrip antenna is presented. The antenna is based on a circular patch antenna and its circular polarization is obtained by taking advantage of the interaction of antenna cavity field with magnetized ferrite disks inserted in the cavity region. The physics of this effect is based on creation of electromagnetic vortices. The scattering and radiation parameters of the antenna are investigated. The dependence of the axial ratio and the return loss of the antenna on the position of the ferrite disks underneath the patch are analyzed. It is shown that the circular polarization can be switched if the polarity of the bias magnetic field is reversed.