Dual-Polarized Microstrip Antennas with Capacitive via Fence for Wide Beamwidth and High Isolation

A dual-polarized microstrip antenna loaded with capacitive via fence is proposed for compact size, wide beamwidth, and high isolation. By exploring a capacitive blind-via fence near the radiating apertures, the field is concentrated between the fence and ground, achieving obvious dimension miniaturization and wide beamwidth for regular dual-polarized microstrip antennas. The proposed blind-via fence is constituted by four rows of metallic wires with subwavelength diameter, period, and gap to the ground. Thanks to the field concentration brought by the blind-via fence, high isolation is realized by suppressing the radiation from the feeding probes, similar to two disk-loaded monopole antennas, and forcing the fundamental mode of the patch. To validate the proposed concept, a prototype is fabricated and characterized with the size of 0.19 \lambda _{0} \times 0.19\,\,\lambda _{0} \times 0.07 \lambda _{0} ( \lambda _{0} is the free-space wavelength at the center frequency). The simulated and measured results agree well, with wide half-power beamwidth of 107° and 105° in the E- and H-planes, respectively. Meanwhile, the port isolation is higher than 32 dB within the operating bandwidth of 2.48-2.56 GHz. The proposed antenna is with the merits of compact size, wide beamwidth, and high isolation, exhibiting potential usage in diversity or multiple-input and multiple-output (MIMO) systems with wide-coverage applications.