Broadband and low-profile patch antenna based on multimode resonance

In order to improve the operation bandwidth and radiation performance of the patch antenna, some techniques are introduced to realize multimode resonances. Through loading shorting walls and shorting pins, the sidelobe of E-plane and the cross-polarization of H-plane are suppressed, and the resonant frequency of TM_1/2,0 mode is increased. Then, a rectangular slot is etched at the current zero point of the TM_3/2,0 mode to excite the resonant slot mode TM_RS. At last, through increasing the width of the patch and adjusting the positions of the shorting pins and the resonant slot, the resonant frequency of TM_1/2,2 mode approaches the other three resonant frequencies, which leads to the realization of four-mode patch antenna. The simulated and measured results demonstrate that the four-mode patch antenna realizes the fractional bandwidth of 21.7% (2.67−3.32 GHz) with the height of 0.03λ₀.