This letter presents a sub-6 GHz cost-effective wideband dual-polarized plane wave generator (PWG) design for the fifth-generation (5G) base station over-the-air test. The proposed nonuniform PWG design is composed of 256 elements and has a dimension of 1.7 m × 1.7 m. Several novel strategies are proposed and implemented to reduce the cost and complexity. To reduce the feeding network complexity and mutual coupling among PWG elements, a novel tapered amplitude-only excitation method (i.e., with the same relative phase excitations among all PWG elements) is proposed. To reduce the number of channels in the phase and amplitude control network, a four-element subarray is applied. Furthermore, the wideband PWG element design and nonuniform configuration are applied to support for ultrawideband operations from 2 to 5 GHz. The proposed PWG design is numerically simulated and experimentally validated. A cylindrical quiet zone of a diameter of 0.9 m and a depth of 0.9 m, with 2.1 m distance to the PWG, is achieved in the measurement for the considered bandwidth, with the typical peak-to-peak E-field amplitude and phase variations less than ±1.25 dB and ±7.5°, respectively, which demonstrated its effectiveness and robustness.

This paper presents a compact dual-polarized over-the-air (OTA) testing antenna with low radar cross section (RCS) for the fifth-generation (5G) and emerging wireless communication systems. The proposed antenna design is achieved by slotting two orthogonal Vivaldi antennas in a cross shaped form into a two-part three-dimensional (3D) printed radome and loading microwave-absorbing materials (MAMs) at the antenna's outer edges. The proposed antenna has a rocket-nest shape with a diameter of 63.4 mm and 113.68 mm length. The -10 dB impedance bandwidth (S11) is obtained from a range of 2.1 up to 6 GHz. The two-part radome is formed by polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) dielectric materials, respectively. Their respective dielectric constants are approxi- mately 2.6 and 4.5 within the -10 dB impedance bandwidth. The MAMs geometry and distribution location are optimized to suppress induced current over the antenna. An antenna prototype has been fabricated and measured. The measured results agree reasonably well with the simulated results. The results show that the use of the two-part radome enables the achievement of low-RCS with compact form factor. Furthermore, a low bistatic RCS of between 1.5 and 6 GHz is observed in simulation for angular ranges of $\theta\in[-30^\circ,+30^\circ]$ and $\phi\in[-90^\circ,+90^\circ]$ .

Plane Wave Generator (PWG) has recently attracted great attention from industry and academia for over-the-air (OTA) testing of base station (BS) antennas in the fifth-generation (5G) wireless communication systems. This paper aims to reduce the scattering from the PWG to the antenna under test (AUT), which might be problematic in the near-field OTA testing. First, we introduce a low monostatic radar cross section (RCS) PWG array element design. The PWG is also loaded with pyramidal microwave absorbing material (MAM) to suppress the multi-reflections between the AUT and the PWG. Furthermore, unlike coplanar PWG design generally reported in the literature, a novel non-coplanar design is proposed to realize the destructive interference of the scattered signals from the PWG, thereby significantly reducing the multiple reflections. PWG elements in the non-coplanar design are placed in the propagation direction according to planar and non-planar field distribution on the PWG radiated from the BS AUT. To validate our proposed design, a 4W4 PWG array with a 108 mm element spacing and a non-coplanar structure is developed and experimentally validated. The measured results show that the second incident wave of the proposed non-coplanar PWG array structure based on non-planar field distribution is 7.9 dB lower than that of the classical coplanar PWG design from 2.3 GHz to 3.8 GHz, and 1.9 dB lower than that of the proposed non-coplanar PWG array structure based on planar field distribution, which demonstrates the effectiveness and robustness of our proposed design.

A high channel consistency subarray of plane-wave generators (PWG) is described for fifth-generation (5G) base station (BS) over-the-air (OTA) testing. Firstly, the variation of the near field radiation characteristics of the subarray based on the feed amplitude and phase errors of the traditional power divider network is analyzed. The recommended amplitude and phase errors between channels are given. After that, a novel subarray which combines four pyramidal horn antennas and a compact 1:4 waveguide power divider is designed. The optimized perfectly symmetrical zigzag waveguide transmission lines are used to realize consistent power allocation among antenna elements. No intermediate pins are employed, which avoids the significant deterioration of channel consistency caused by assembly errors. The size of the subarray is 4.89 λ₀ × 4.97 λ₀ × 1.23 λ₀ (λ₀ is the working wavelength corresponding to the subarray center frequency at 3.5 GHz). The VSWR < 1.5 impedance bandwidth covers 3.4 GHz to 3.6 GHz. The amplitude difference between the four elements of the subarray is less than 0.5 dB, and the phase difference is less than 3°. The simulated and measured results agree well in this design.