Modified ${\rm TM}_{020}$ Mode of a Rectangular Patch Antenna Partially Loaded With Metamaterial for Dual-Band Applications

In this letter, the TM₀₂₀ mode of a rectangular patch antenna is modified by partially loading a mu-negative (MNG) or double-negative (DNG) metamaterial block. With proper constitutive parameters and filling ratio, the electric fields at two radiating edges of the patch can be out of phase, and a broadside radiation pattern is achieved. A novel dual-band rectangular patch antenna loaded with a pair of conventional double-positive (DPS) and MNG metamaterial blocks is proposed as an application example of the modified TM₀₂₀ mode. Good impedance matching and similar patterns with broadside radiation are achieved simultaneously at both operating frequencies with a single-layer single-patch fed by a single coaxial line. Simulation shows that the modified TM₀₂₀ mode gives an efficient radiator with sufficient gain and very low level of cross polarization. Partial loading of a DNG metamaterial block is also discussed for some special dual-band applications.