A Low-Profile Wideband Dual-Polarized Microstrip Patch Antenna under Multi-Resonant Modes

A low-profile wideband differential-fed dual- polarized microstrip patch antenna (MPA) based on three resonant modes is proposed. First, a differential feeding scheme is selected to suppress unnecessary modes and effectively reduce the cross-polarization level of the antenna. Next, a cross slot is etched out on the radiating patch and an array of shorting pins are loaded underneath the patch. Their main target is to resonate the antenna in two resonant modes. After that, an additional resonant mode is excited by using two pairs of L-shaped probes. With these arrangements, two resonant modes of the MPA and a resonant mode of the L-shaped probes are moved closely to each other, thus effectively extending its impedance bandwidth to about 22.6%. Meanwhile, it still keeps a low-profile property of about 0.029λ0 (λ0 is the free space wavelength). Additionally, the isolation between these differential-fed reaches to about 60 dB.