A low-profile wideband dual-polarized antenna with gain enhancement, low gain variations, and low cross polarization for 5G indoor communications

A low-profile wideband dual-polarized antenna with high gain, low gain variations, and low cross-polarization for the fifth generation (5G) indoor distribution system is proposed. By using circular-thread vase-shaped structure, a low profile of 0.23 lambda(0) (lambda(0) is the free-space wavelength at the starting frequency) as well as low gain variation feature can be achieved by the vertically polarized (VP) radiating element. An eight-way power divider network is employed to feed the horizontally polarized (HP) dipoles so that wideband performance is obtained. Here, eight pairs of arc-shaped parasitic strips are used to broaden the bandwidth, and eight pairs of director elements are introduced to enhance the gain and reduce the gain variations. In addition, the protruded stubs that are extended from the circular ground plane will help to reduce the cross polarization in the VP direction. Measured results show that a bandwidth of 46.5% (3.3-5.3 GHz) (S-11 < -10 dB) with a gain of 0.85 +/- 0.35 dBi, and another bandwidth of 85.0% (2.5-6.2 GHz) with a gain of 4.75 +/- 1.75 dBi can be realized in the HP and VP directions, respectively. Furthermore, high isolation (>27 dB) and low cross polarization (<-24 dB) can also be attained. Therefore, the proposed antenna is a good candidate for 5G indoor distributed system.