A Low-Profile, Wideband, Dual-Polarized Patch Dipole With Unidirectional Radiation Patterns

Abstract

Abstract-A low-profile, wideband dual-polarized antenna with unidirectional radiation patterns is the design goal of this paper. To obtain such antenna characteristics, the design is divided into two steps. First, a coax-feed wideband antenna element with a simple geometry is proposed. The antenna element consists mainly of a quasi-square patch-dipole, a coupling E-shaped feeding structure and a shorting pin. The electromagnetic coupling between the feeding structure and the non-contact quasisquare patch can be flexibly controlled by a pair of fan-shaped stubs. Secondly, two pairs of the proposed antenna elements are selected to construct a dual-polarized antenna. To further reduce the profile of the antenna, two techniques are utilized. One is the mutual coupling distributing among the elements while the other is to add four rectangular stubs within the inner region. A prototype of the dual-polarized antenna is fabricated and measured. Measurement results demonstrate that the prototype antenna obtains an overlapped fractional bandwidth of 38.9% from 1.7 to 2.52 GHz with a good isolation higher than 32 dB. Both unidirectional radiation patterns with front-to-back ratios better than 20 dB across the whole frequency band and cross polarization levels lower than −22 dB in most operating frequency band are obtained. Additionally, the dual-polarized antenna achieves average gains about 9.9 dBi and 10.1 dBi for Port 1 and Port 2, respectively.