With the introduction of 5G communication systems operating in the mm-wave frequency range, new opportunities in terms of multimedia services and applications will become available. For this to happen, several technical challenges from an antenna standpoint need to be addressed. The achievements of high-gain characteristics and agile beamforming with wide-scan capabilities are the main targets of the ongoing research on mm-wave antenna arrays. In this paper, an up-to-date overview of antenna array technology for wireless communications at mm-wave frequencies is given. Particular focus is put on the review of the state-of-the art and most advanced antenna array concepts for point-to-point and point-to-multipoint radio links at said frequencies. Various figures of merit are assessed for a comprehensive analysis and bench marking of the technical solutions investigated in the presented survey.

In order to cope with the needs of fifth-generation (5G) cellular networks and beyond, phased-array antenna systems operating at millimeter-wave (mm-wave) frequencies will be required. This makes the system design very complex. In order to create insight and agility in the design process, we propose a framework that visualises the requirements and trade-offs of 5G-and-beyond systems. Our literature survey uses this framework to compare state-of-the-art papers on Silicon-based beamforming integrated circuits (BFICs) operating in the mm-wave band. Three use-cases are analyzed: Base-stations (BSs), Gateways (GtWs) and User Terminals (UTs). Based on the framework, we explore which implementation fits best with each use-cases. In UT, space and power consumption are the main constraints. For BSs, the main constraint is in output power and noise figure (NF). Finally, in GtW applications there is more flexibility as it has a larger footprint than UT but doesn't necessarily need to cover the same link-budget constraints of BSs. One of the identified limitations throughout all the cases is the heat generation, which is seen as a major bottleneck in mm-wave phased arrays. Only a few of the references show proper modelling and simulations for heat transfer of the realized BFICs. Finally, a limitation in the BFICs is the output power. In order to realize a mm-wave link at least 13 dBm would be required at the input of each antenna element. Only few references meet this criterion, and only at saturation. Further, in order to achieve more than 13 dBm in back-off operation a higher power density would be required. This would imply a further increase of heat generation in the system.

Conformal array pattern synthesis represents a challenging problem for current state-of-the-art design techniques. To their detriment, these techniques typically suffer from a significant computational burden. A deterministic method for the synthesis of singly curved conformal antenna arrays based on the superformula and the auxiliary array pattern (AAP) formulation is presented. This method, being semianalytical in nature, is able to evaluate the location and excitation coefficients of each radiating element subject to different design constraints in a deterministic manner while utilizing multiple embedded element patterns. Therefore, this method is more computationally efficient than the state-of-the-art alternatives. The proposed synthesis technique has been validated through full-wave electromagnetic simulations and experimental measurements taken on physical demonstrators relevant to different applications within radar and communication systems. The obtained results show accurate agreement between simulations and measurements, requiring only seconds of computation on conventional hardware.

In this paper, a novel multi-mode millimeter-wave antenna array with enhanced scan range and reduced scan losses is presented. The individual array element consists of a differentially fed microstrip patch on top of which a cylindrical dielectric resonator is integrated. The radiation pattern of the antenna element can be reconfigured by changing the phase offset between the feeding ports of the patch and the dielectric resonator to excite two distinct radiating modes. With such a feature, the field of view can be divided into two different subspaces, with the first one covering the angular range from -75to 0and the second one from 0to +75. In a 1 × 16 linear array configuration, the achieved scan range extends from -75to 75along the horizontal plane with a maximal gain loss of 3 dB, which is better than the ideal cos θ0 behavior. The proposed design operates in the frequency range between 27 GHz and 29.5 GHz and, thanks to its wide-scan capabilities, constitutes an effective solution for upcoming 5G/6G millimeter-wave wireless communications.

State‐of‐the‐art conformal array pattern synthesis techniques typically suffer from a significant computational burden. This article builds upon the auxiliary array pattern synthesis technique, allowing the technique to work on elliptical contours. This deterministic method is both computationally efficient and capable of handling complex design cases with additional design constraints. In order to highlight the versatility and applicability, the method has been applied to an elliptical arc array comprised of Rampart antennas and an elliptical ring array using dipole elements. The results have been validated through full‐wave electromagnetic simulations, as well as physical measurements. Both arrays presented show good agreement with the proposed synthesis technique. Highlighting the ability to satisfy additional design constraints, such as enforcing a minimal element spacing or having a controlled beamformer‐network complexity.

Energy-efficiency is crucial for modern radio-frequency (RF) receivers dedicated to Internet of Things applications. Energy-efficiency enhancements could be achieved by lowering the power consumption of integrated circuits, using antenna diversity or even with an association of both strategies. This paper compares two wideband RF front-end architectures, based on conventional low-noise amplifiers (LNA) and low-noise transconductance amplifiers (LNTA) with N-path filters, operating with three transmission schemes: single antenna, antenna selection and singular value decomposition beamforming. Our results show that the energy-efficiency behavior varies depending on the required communication link conditions, distance between nodes and metrics from the front-end receivers. For short-range scenarios, LNA presents the best performance in terms of energy-efficiency mainly due to its very low power consumption. With the increasing of the communication distance, the very low noise figure provided by N-path LNTA-based architectures outperforms the power consumption issue, yielding higher energy-efficiency for all transmission schemes. In addition, the selected front-end architecture depends on the number of active antennas at the receiver. Hence, we can observe that low noise figure is more important with a few active antennas at the receiver, while low power consumption becomes more important when the number of active RF chains at the receiver increases.