A novel high-gain dielectric resonator antenna (DRA), featuring a peak realized gain of 11.3 dBi over a fractional bandwidth of 16.6% around 30 GHz, is presented. The proposed antenna structure, excited by a slot coupled microstrip line, is composed of a cylindrical dielectric resonator and of a truncated plastic-based conical horn useful to enhance the gain. An annular perturbation notch is realized in the dielectric horn to achieve a better focusing of the RF energy along the antenna boresight direction, while reducing the side-lobe levels (SSLs). The presented antenna design achieves SSLs below -10 dB for both the E- and H-plane so to meet the requirements of next-generation 5G wireless communication protocols and of low-cost satellite and mobile systems.

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.

We review dielectric resonator antenna (DRA) designs. This review examines recent advancements across several categories, specifically focusing on their applicability in array configurations for millimeter-wave (mmW) bands, particularly in the context of 5G and beyond 5G applications. Notably, the off-chip DRA designs, including in-substrate and compact DRAs, have gained prominence in recent years. This surge in popularity can be attributed to the rapid development of cost-effective multilayer laminate manufacturing techniques, such as printed circuit boards (PCBs) and low-temperature co-fired ceramic (LTCC). Furthermore, there is a growing demand for DRAs with beam-steering, dual-band functions, and on-chip alignment availability, as they offer versatile alternatives to traditional lossy printed antennas. DRAs exhibit distinct advantages of lower conductive losses and greater flexibility in shapes and materials. We discuss and compare the performances of different DRA designs, considering their material usage, manufacturing feasibility, overall performance, and applications. By exploring the pros and cons of these diverse DRA designs, this review provides valuable insights for researchers in the field.

Electronically controlled antenna arrays, such as reconfigurable and phased antenna arrays, are essential elements of high-frequency 5G communication hardware. These antenna arrays are aimed at delivering specified communication scenarios and channel characteristics in the mm-wave parts of the 5G spectrum. At the same time, several challenges are associated with the development of such antenna structures, and these challenges mainly originate from their intended mass production, contemporary manufacturing technologies, integration with active RF chains, compact size, dense circuitry, and limitations in postmanufacturing tuning. Consequently, 5G antenna array designers are presented with contradictory design requirements and constraints. Furthermore, these designers need to handle large numbers of designable parameters of the antenna array models, which can be computationally expensive, especially for repetitive and adaptive simulations that are required in design optimization and tuning. Antenna array synthesis, namely, the process of finding positions, orientation, and excitation of the array radiators, is a challenging yet crucial part of antenna array development. This process ensures that the performance requirements of the antenna array are met. Therefore, there is a need for reliable yet fast automated computer-aided design (CAD) and synthesis tools that can support the development of 5G antenna array solutions, from the initial prototyping stage to the final manufacturing tolerance analysis. This paper presents an overview of recent advances in antenna array synthesis from the viewpoint of their applicability to the design of electronically reconfigurable and phased antenna arrays for wireless communications and remote sensing.

A novel technique is presented for the design and optimization of waveguide antenna arrays based on overlapping sub-arrays for limited field-of-view applications. Each sub-array consists of one directly-fed antenna element and several passive reactive-loaded elements. The proposed overlapping scheme exploits a free-space reactive coupling instead of more conventional schemes based on complex beamforming networks. This results in a drastic reduction in the number of waveguide components required in the feeding network. The optimization of the considered class of array structures using a full-wave EM solver is extremely time-consuming even in the presence of sub-arrays with a reduced number of passive elements. To overcome this limitation, an effective semi-analytical design algorithm has been specifically developed. Using this algorithm, a novel sub-array structure with a predefined pulse-shaped radiation pattern was synthesized. The designed sub-array is inherently matched and features reduced spurious electromagnetic coupling level with adjacent sub-array elements. In particular, the analysis of an array consisting of 38 such sub-array elements has been carried out with the main goal of illustrating the effect of the sub-array pattern on the total array characteristics. To validate the sub-array overlapping scheme, an array composed by 3 contiguous sub-arrays has been realized and measured experimentally. In this way, a scan range in the field of view [-4°; 4°] with 15dB grating lobe suppression has been demonstrated.

A deterministic approach to the synthesis of a general aperiodic arc or ring antenna array is presented and thoroughly detailed in Part I of this work. The proposed technique, which is based on the auxiliary array pattern concept, is aimed at the semi-analytical determination of the optimal excitation tapering and array element angular distribution for mimicking a given radiation pattern mask, without resorting to any optimization procedure. This, in turn, enables a dramatic reduction in design times. The developed technique is validated by application to the synthesis of antenna arrays featuring different radiation pattern masks typically adopted in satellite communications and radar applications; the relevant results are reported in Part II.