Higher-Order Modes in High-Permittivity Cylindrical Dielectric Resonator Antenna Excited by an Off-Centered Rectangular Slot

In this letter, we study the higher-order modes excited in a high-permittivity cylindrical dielectric resonator antenna (DRA), situated asymmetrically on top of a rectangular slot in the ground plane of a microstrip line. Besides the modes excited by a symmetric positioning of the DRA above the feeding slot, we identified five new modes: ${\rm TEme}_{010}$ , ${\rm TEme}_{011}$ , ${\rm TEme}_{210}$ , ${\rm TEme}_{020}$ , and ${\rm TM}_{212}$ , respectively. The higher-order modes offer to the DRA antenna some interesting features: They have different radiation patterns for different operating modes; modes with close resonance frequency give wideband capabilities; and sometimes, when a mode has poor performance in one polarization, it is possible that another mode with close frequency can compensate it.