60-GHz dual-polarized multi-beam magneto-electric dipole array

Abstract

Millimeter-wave multi-beam antenna arrays with passive beam-forming networks are attractive for future millimeter-wave base stations and mobile devices employing the multiple input multiple output (MIMO) technique owing to their advantages of simple structure, low cost and low power consumption. Several kinds of millimeter-wave multi-beam antenna arrays with one or two dimensional beams were investigated. The patch or the slot antenna was selected as the radiating element of most designs because of their simple geometries and convenience of integration. However, due to the narrow bandwidth performance or the unstable radiation pattern across the operating band, these designs generally suffer from narrow impedance bandwidth or radiation pattern bandwidth. Moreover, most arrays are linearly polarized. As well known, dual-polarized arrays are widely used for wireless communication systems operating at lower microwave frequencies because of significant advantages of polarization diversity and enhancing channel capacity. Therefore, dual-polarized arrays would also be attractive for emerging wireless systems operating at millimeter-wave frequencies. Recently, a new class of wideband antennas designated as the magneto-electric (ME) dipoles was proposed. By applying the concept of complementary antenna, the basic structure consists of a planar electric dipole and a shorted quarter-wave patch antenna working as an equivalent magnetic dipole. The ME dipole has excellent performance including wide impedance bandwidth, nearly identical radiation patterns in two orthogonal planes, low back radiation, low cross polarization, and stable gain over the operating band, and maintains a simple structure as well. In this talk, a novel substrate integrated waveguide (SIW) fed aperture-coupled dual-polarized magneto-electric (ME) dipole antenna will be presented at millimeter-wave frequencies. By applying the aperture coupling as the excitation scheme, the dual-polarized radiations can be easily excited by two sections of SIW located in two layers of print circuit board (PCB). Besides, it has good characteristics including wide bandwidth, high radiation efficiency, symmetrical radiation patterns, low back radiation, low cross polarizations and high isolation between the two input ports. Based on the radiating element, a 2 × 2 dual-polarized two-dimensional multi-beam array working at the 60-GHz band is then designed. Owing to good performances of the ME dipole antenna, the proposed array has wide bandwidth and symmetrical radiation patterns.