Bandwidth-Enhanced High-Gain Microstrip Patch Antenna Under TM₃₀ and TM₅₀ Dual-Mode Resonances

This letter presents a bandwidth-enhanced single-layer differential-fed microstrip patch antenna (MPA) under the operation of dual radiative TM30and TM50modes. A pair of long slots is symmetrically etched on specific positions of the upper microstrip patch, where the electric field of TM30mode is at the peak point, while simultaneously the electric field of TM50mode is at the null point. Thus, the capacitive effect of the installed slots effectively reallocates the TM50mode to a much lower frequency region in close proximity to that the of less-influenced TM30mode one, resulting in a wide operating bandwidth with dual-resonant radiation. Due to the same odd-order field distribution, the dual radiative modes produce the same maximum radiation in the broadside direction. Compared with other multimode patch antennas, the proposed one can be simply implemented in a single-layer substrate with the height of only 0.8 mm (0.0146 free-space wavelength at 5.5 GHz). An antenna prototype is designed, implemented, and measured. Tested results verify that the proposed antenna owns an enhanced operating -10 dB bandwidth of 6.1% (5.4-5.74 GHz) and a maximum realized gain of 10.7 dBi, demonstrating the advanced performance of the proposed dual-mode MPA.