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.