Manipulation of the Radiation Characteristics of a Patch Antenna by Small Ferrite Disks Inserted in Its Cavity Domain

In this paper, it is shown how the radiation characteristics of a patch antenna can be manipulated by a small number of normally magnetized ferrite disks inserted in the resonant region of the patch. It is shown that a one- and dual-band circular polarized microstrip antenna can be obtained by taking advantage of the interaction of the antenna cavity field with the magnetized ferrite disks. 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 and the number of ferrite disks underneath the patch are analyzed. Experimental and simulation results are in good agreement.