This paper presents an improved approach for the synthesis of sparse planar arrays using density-weighted method and chaos sparrow search algorithm (CSSA) with multiple constraints. The approach consists of two stages and has an efficient way in dealing with multiple constraints, including the array aperture, number of elements, and minimum spacing between adjacent elements. In the first step, a density-weighted method is implemented to generate a thinned array structure by introducing the weighted coefficient based on the distribution function of a uniform full array to the elements, which can reduce the time and improve the efficiency of the optimization of sparse matrices. On the basis of a density-weighted array, tent chaotic mapping is introduced to initialize the population, then sparrow search algorithm (SSA) is used to further optimize the location of each element of the array antenna to search for the global optimal solution. As a consequence, the proposed method exhibits improved flexibility with respect to other analytical techniques, and reduces the computational cost of the optimization algorithm. Numerical validation results demonstrate the effectiveness and reliability of the proposed method, showing that it can achieve better results than existing methods in the design of sparse planar array arrangements.

Next-generation wireless communication requires antennas with excellent performance and low-profile structures. A low-profile broadband dual-polarized base station antenna array with an artificial magnetic conductor (AMC) reflector and cross-polarization suppression structures is proposed. Cross-polarization is effectively suppressed by introducing the structures among the antenna elements with almost no impact on the other antenna performances, and the cross-polarization suppression mechanism is analyzed theoretically. The AMC reflector reduces the antenna profile only $0.12\lambda _{0}$ ( $\lambda _{0}$ is the free-space wavelength at 4 GHz). Prototypes of the antenna element and the five-element antenna array are fabricated, and the simulated and measured results indicate that both achieve good performance over the entire operating frequency band. The antenna array has high isolation (>28 dB), a wide operating bandwidth (3.14–5.32 GHz, 51.5%), and stable radiation performances (XPD >29 dB, gain >15 dBi, FBR >37 dB). The proposed antenna array with good performance and a low profile may be a candidate for 5G communication applications.

A novel dual‐wideband dual‐polarised magnetoelectric (ME) dipole antenna for the fourth generation (4G)/fifth generation (5G) microcell base station is proposed. Using a pair of orthogonal ME dipoles and Γ‐shaped tapered cross feeding lines, the initial antenna achieves dual‐band and dual‐polarised. Then, four U‐shaped gaps, added in electric dipoles, effectively extend the lower impedance bandwidth. Finally, a circular parasitic patch with capacitive properties is innovatively loaded above the ME antenna, which obviously reduces the high‐resonant frequency from 5.5 to 4.9 GHz. Meanwhile, a box‐shaped reflector is employed to achieve stable gain and radiation patterns. As a result, the measured results show the good dual‐wideband performance of 52.4% (2.14–3.66 GHz) and 7.4% (4.68–5.04 GHz) with voltage standing wave ratio (VSWR) < 2, high isolation (>25 dB) and high gain (9.5 and 5.5 dBi, respectively). In addition, a stable radiation pattern with a half‐power beam width of and good cross‐polarisation discrimination (>20 dB) on the E ‐plane is realised over these two bands.

A broadband dual-polarized base station antenna is proposed in this paper. The antenna consists of loop cross-dipoles, Y-shaped coupling feeding lines, and a metal box reflector. An equivalent circuit model including a signal flow diagram is established to analyze the mechanism of the proposed antenna in detail. Moreover, the Y-shaped coupling feeding lines are introduced to control the coupling with the antenna to achieve broadband and good impedance matching. The prototype of the antenna is fabricated and measured. The measured results show that the antenna with simple structures can operate at the band of 3.2–5.22 GHz (48%) with high port-to-port isolation (35 dB) and stable gain (9 ± 1 dBi). The measured results show good agreement with simulated results, especially in cross-polarization discrimination ratio (>27 dB) and the half power beam width (61° ± 3° at the E-plane, 68° ± 3° at the H-plane). In summary, the proposed antenna could be a good candidate for 5G sub-6 GHz base station applications.

A novel design method of a low sidelobe antenna array is proposed in this paper. By combining the Chebyshev array synthesis theory and the sparse array synthesis theory, the sidelobe level (SLL) of the antenna array is greatly reduced. Compared with the traditional Chebyshev array synthesis theory, the proposed method is effective to reduce the SLL of the antenna array (SLL reduced by 6.8 dB at Phi = 0° and SLL reduced by 4.5 dB at Phi = 90°). According to the method proposed above, an antenna array applies for 24 GHz vehicle radar is designed and simulated. The measured results show that the antenna has wide bandwidth (23.6 GHz~25.07 GHz, 1.47 GHz), high gain (20.7 dBi), and extremely low sidelobe level (−28.8 dB at Phi = 0° and −25 dB at Phi = 90°). In summary, the antenna with good performance and simple structure is easy to be integrated, which can provide some reference for the design of the 24 GHz vehicle radar antenna.