In the following, we propose a dual-polarized double-layer metasurface lens based on split dipole unit cells. The characteristic mode analysis (CMA) of a split electric dipole shows two characteristic modes over the band of interest. By exciting these two modes with a certain phase difference, the reflection at normal incidence can be canceled. Inspired by this idea, a planar dual-polarized unit cell based on four pairs of split electric dipoles is designed on a single-layer substrate. A phase range of 396° and a transmission coefficient with a magnitude higher than 0.8 is achieved. For experimental verification, a metasurface lens with 36×36 elements is designed at 30 GHz with a focal diameter ratio of 0.84. The measured peak gain is 31.6 dBi at 31 GHz with an aperture efficiency of 45% and 1-dB/3-dB gain bandwidth of 7.3%/14%, respectively. Due to the dual-polarized operation, the relative high aperture efficiency and the low-cost design the proposed metasurface lens is a promising candidate for millimeter-wave communication, e.g. 5G and satellite communication systems.

A novel W-band two-dimensional (2-D) monopulse sparse array antenna with suppressed sidelobe levels is proposed in this paper. The 2-D monopulse antenna is composed of a radiation sparse array, an irregular interconnected waveguide-based network, a power divider network, and a sum-difference network. The sparse array uses a box-horn as the radiation element and is optimized based on the genetic algorithm, which exhibits low sparsity and low sidelobe levels. The whole aperture of the antenna is divided into four subarrays. To feed all the radiating elements that are randomly distributed in the subarrays with the same amplitude and equal phase, an irregular interconnected waveguide-based network and a power divider network are designed. Finally, a sum-difference network is connected to the end of the four subarrays to obtain the sum and difference radiation performance results for the monopulse antenna. A 2-D monopulse sparse array antenna with 32 radiating elements is fabricated and measured. The measured |S11|≤-10 dB bandwidth of the antenna is over 6 GHz (from 90 GHz to 96 GHz). At the center frequency, the maximal gain of the sum radiation pattern is approximately 24.0 dBi, with low sidelobe levels (both E-plane and H-plane) less than -19.0 dB. Additionally, the null depth of the difference radiation pattern is less than -30.0 dB.

This paper describes the design and realization of a novel Ka/W dual-band shared-aperture horn antenna employing the concept of mutual enhancement. The W-band antenna cells within the Ka-band antenna structure enhance the aperture utilization efficiency. The proposed design enables gain enhancement in the Ka-band horn antenna through incorporation of W-band horn antenna cells, while the W-band array antenna achieves low sidelobe levels by adopting a sparse array configuration. The W-band antenna consists of a radiation sparse array, an irregular interconnected waveguide-based network, and a power divider network. A mutually enhanced Ka/W dual-band shared-aperture horn antenna is fabricated and evaluated. The results reveal a gain improvement of 1.5 dB at 35 GHz compared to the original horn antenna. Moreover, the measured |S11|≤-10 dB bandwidth of the W-band array antenna spans over 16 GHz (ranging from 92 GHz to 108 GHz). At the central frequency, the maximal gain of the radiation pattern is approximately 20.8 dBi, with low sidelobe levels (in both the E-plane and the H-plane) of less than -19.0 dB.