Differentially Fed Dual-Mode Patch Antenna With Wideband Common-Mode Absorption and Its Array Application

A differentially fed dual-mode patch antenna is proposed with wideband common-mode (CM) absorption. The proposed antenna consists of a differential feeding network, common ground plane, and the radiation patch with stepped widths. The differential feeding network is formed by adding an absorptive stub at the symmetric plane of balanced microstrip structure to achieve wideband CM absorption. Besides, a T-shaped slot is etched on the ground plane to realize aperture coupling to excite the radiation under TM
₀₁
and TM
₁₁
modes. Subsequently, the differential parallel feeding technique is employed to design a
$2 \times 4$
planar array with low cross polarization. As demonstration, the prototypes of the designed differential antenna and array are fabricated and measured. The measured results show that the proposed antenna element and array exhibit the broadened −10 dB impedance bandwidths covering the frequency range of 4.8–4.99 GHz, wide CM absorption band with about 70% fractional bandwidth, and low cross polarization below −20 dB. Furthermore, the measured peak realized gains of antenna and planar array are 7.5, and 16.6 dBi, respectively.