A wide-scan and broadband focal-plane array (FPA) concept is introduced in this article, which provides high antenna gain and effective isotropic radiated power (EIRP) with electronic beamsteering within a relatively large field of view (FoV), up to +/-20°. The antenna uses a bifocal double-reflector concept that optimizes the illumination of the focal-plane region. In this way, we have reduced the required size of the feed array and have maximized the number of simultaneously active array elements. By using a photonics beamformer, a broadband system for the 20-40-GHz band can be created with a fiber-based interface to a central processing unit. This hybrid antenna system is a very interesting concept for future 5G and beyond [5G millimeter-wave (mm-wave) base stations, two-way satellite communication systems, and point-to-point wireless backhaul systems]. A silicon BiCMOS low-noise amplifier (LNA) and a photonic integrated circuit (PIC) for the optical beamformer have been developed and integrated into the overall system. A system-level demonstrator was developed and experimentally validated in receive mode. Our concept provides an antenna gain of more than 40 dBi over an FoV of +/-15° at 28.5 GHz.

This article introduces the FORMAT array, a reconfigurable millimeter-wave antenna array platform based on antenna tiles. FORMAT stands for Flexible Organization and Reconfiguration of Millimeter-wave Antenna Tiles, which is a unique hardware solution aiming to implement and demonstrate a variety of antenna array concepts, as well as different array architectures and configurations from the same basic module, providing even benchmark between different solutions and thus valuable insights into fifth-generation (5G) and beyond-5G antenna systems. The combination of a minimum-sized $2\times 2$ tile with 3D-printed frame parts enables antenna arrays of a variety of sizes, allows multiple beamforming architectures, and a range of different antenna element positioning in the array. The hardware implementation is thoroughly described, with a few different array assemblies being manufactured and measured, validating their antenna performance with over-the-air measurements. Finally, using FORMAT hardware as both base station and user equipment, a 5-m wireless communication link was set up, achieving 4.8 Gbps downlink speed with QAM64 modulation.

Lower efficiencies of power amplifiers and increased path losses at higher frequencies are two reasons why utilizing millimeter-wave frequencies for future wireless communications is challenging. In this paper, a high-gain multi-lens-horn antenna system is presented. The antenna system provides high effective isotropic radiated power by using only a few high-gain antenna elements, where each element only needs a low transmit power of 26dBm to reach users at far distances. Moreover, due to channel reciprocity, both down-and uplink benefit from an increased antenna gain. It is shown that a reasonable number of high-gain antennas can provide coverage in a 60∘ sector with an inter-site distance of 300 meters. Based on radio planning simulations, three horn shapes are identified to provide sufficient coverage. The final optimized dual-polarized multi-lens-horn design is fabricated and experimentally verified. With a low transmit power at the base station of 26dBm, a signal strength of at least -65dBm is achieved in 98.9% of the sector at 28GHz under non-line-of-sight conditions for the vertical polarization. For the horizontal polarization, an area of 96.2% is covered.

The use of millimeter-wave (mm-wave) frequency bands for fifth-generation cellular mobile communications (5G) has led to intense interest from academia and industry over these spectrum resources. Despite extensive measurement campaigns and channel modeling efforts, there is a lack of deterministic back-scattering models addressing the impact of the size and orientation of static scatterers on the radio channel. In this paper, two three-dimensional (3D) computationally-efficient methods for calculating back-scattering based on the Fresnel integrals and the error function are proposed and validated both against EM simulations and measurements. In addition, applying the same methodology, state-of-the-art mm-wave blockage (forward-scattering) models are modified to capture back-scattered fields. Furthermore, both the introduced and the modified models preserve the structure of geometry-based stochastic channel models (GSCMs) and thus their implementation in system-level simulators is substantially beneficial due to their good accuracy and short computation time.