Compact Wideband Dual-Polarized Antenna With High Isolation Using Modified Direct Feeding Structure For Indoor Beamforming Array Applications

• Main Authors: Yaohui Zhang, Daotong Li, Yonghong Zhang, Yong Fan
• Format: Article
• Language: English
• Published: IEEE 2018-01-01
• Series: IEEE Access
• Subjects: Modified direct feeding structure; compact; high isolation; wideband; dual-polarized
• Online Access: https://ieeexplore.ieee.org/document/8515192/

A modified direct feeding structure is proposed in this paper to realize a compact (<inline-formula> <tex-math notation="LaTeX">$45 \times 45$ </tex-math></inline-formula> mm²) wideband dual-polarized antenna with high isolation (33 dB) and low cross-polarization (30 dB). Compared with the conventional crossed dipole antennas, two additional pairs of dipoles are employed as coupling baluns as well as radiators. As a consequence, the proposed antenna with more symmetrical structure has the advantages of both the direct feeding (DF) and the coupling feeding (CF) structures, such as, balanced matching, high isolation, low cross-polarization, and compact size. Besides, the gap structure between adjacent dipoles is designed in elliptical shape to further improve the impedance matching. The proposed antenna realizes a wide impedance bandwidth over 51&#x0025; (1.7&#x2013;2.85 GHz) for VSWR &#x003C;1.5. It is worth mentioning that the compact size and high isolation could greatly reduce the element spacing of beamforming antenna array. In order to investigate the performance of beamforming array, a two-element array fed by the out-of-phase power divider network is developed. The lowest operating frequency can be further extended to 1.6 GHz and the cross-polarization discrimination (XPD) is more than 10 dB within &#x00B1;60&#x00B0; of the main lobe.