Antenna Designs Aiming at the Next Generation of Wireless Communication

Millimeter-wave (mm-wave) frequencies have drawn large attention, specically for the fifth generation (5G) of wireless communication, due to their capability to provide high data-rates. However, design and characterization of the antenna system in wireless communication will face new challenges when we move up to higher frequency bands. The small size of the components at higher frequencies will make the integration of the antennas in the system almost inevitable. Therefore, the individual characterization of the antenna can become more challenging compared to the previous generations.This emphasizes the importance of having a reliable, simple and yet meaningful Over-the-Air (OTA) characterization method for the antenna systems. To avoid the complexity of using a variety of propagation environments in the OTA performance characterization, two extreme or edge scenarios for the propagation channels are presented, i.e., the Rich Isotropic Multipath (RIMP) and Random Line-of-Sight (Random-LoS). MIMO efficiency has been defined as a Figure of Merit (FoM), based on the Cumulative Distribution Function (CDF) of the received signal, due to the statistical behavior of the signal in both RIMP and Random-LoS. Considering this approach, we have improved the design of a wideband antenna for wireless application based on MIMO efficiency as the FoM of the OTA characterization in a Random-LoS propagation environment. We have shown that the power imbalance and the polarization orthogonality plays major roles determining the 2-bitstream MIMO performance of the antenna in Random-LoS. In addition, a wideband dual-polarized linear array is designed for an OTA Random-LoS measurement set-up for automotive wireless systems. The next generation of wireless communications is extended throughout multiple narrow frequency bands, varying within 20-70 GHz. Providing an individual antenna system for each of these bands may not be feasible in terms of cost, complexity and available physical space. Therefore, Ultra-Wideband (UWB) antenna arrays, coveringmultiple mm-wave frequency bands represent a versatile candidate for these antenna systems. In addition to having wideband characteristics, these antennas should offer an easy integration capability with the active modules. We present a new design of UWB planar arrays for mm-wave applications. The novelty is to propose planar antenna layouts to provide large bandwidth at mm-wave frequencies, using simplified standard PCB manufacturing techniques. The proposed antennas are based on Tightly Coupled Dipole Arrays (TCDAs) concept with integrated feeding network

Miniaturized DGS and EBG structures for decoupling multiple antennas on compact wireless terminals

MIMO (Multiple Input Multiple Output) technology has been presented to significantly increase the wireless channel capacity and reliability without requiring additional radio spectrum or power. In MIMO systems, multiple antennas are mounted at both the transmitter and the receiver. When this technology is employed for a compact wireless terminal, one of the most challenging tasks is to reduce the high mutual coupling between closely placed antenna array elements. The high mutual coupling produces high correlation between antenna elements and affects the channel capacity of MIMO system. The objectives of this thesis are to design practical miniaturized structures to reduce high mutual coupling for small wireless terminals. The research is conducted in the following areas. Initially, a PIFA design and two-element PIFA array are proposed and optimized to operate at 1.9GHz. A pair of two coupled quarter-wavelength linear slits is inserted in a compact ground plane, resulting in significant reduction of the mutual coupling across antenna operating frequency band. In order to take up less space on the ground plane, instead of the linear slits, miniaturized convoluted slits are implemented between the two closely placed PIFAs. Although the convoluted slits have small area and are positioned close to the edges of the ground plane, the miniaturized convoluted slit structures achieve a reduction of mutual coupling between antenna elements and succeed in reducing the effect of the human body (head and hand) to the antennas. In order to further reduce the size of the slits etched on the compact ground plane, a novel double-layer slit-patch EBG structure is proposed. It consists of a two-layer structure including conducting patches and aperture slits placed on either side of a very thin dielectric layer. They are placed in very close proximity to each other (55μm). A two-element printed CPW-fed monopole array operating around 2.46GHz and a two-element UWB planar monopole array operating from 3GHz to 6GHz have been employed to investigate the proposed slit-patch EBG structures. The optimized double-layer slit-patch EBG structure yields a significant reduction of the mutual coupling and produces the maximum miniaturization of antenna array. Another novel convoluted slit-patch EBG structure has been presented to reduce the mutual coupling between two PIFAs operating at 1.9GHz. These results demonstrate that the slit-patch EBG structure is a feasible technology to reduce the mutual coupling between multiple antennas for compact wireless terminals

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Four-Element MIMO Antenna System for UWB Applications

A four element multiple input multiple output (MIMO) antenna system for UWB applications is presented. The system consists of two identical slot dipoles and two identical planar monopoles. Polarization diversity between different kinds of antennas can realize lower coupling between antenna elements, and by using a couple of inverted L-shaped stubs and an inverted Z-shaped stub as decoupling structures, isolation can be further improved. For both simulation and measurement, higher than 17dB isolation between antenna elements can be obtained through the whole UWB band (3.1-10.6 GHz). The envelope correlation coefficient, antenna gain, efficiency and other performances are also provided

Recent Advances in Antenna Design for 5G Heterogeneous Networks

The aim of this book is to highlight up to date exploited technologies and approaches in terms of antenna designs and requirements. In this regard, this book targets a broad range of subjects, including the microstrip antenna and the dipole and printed monopole antenna. The varieties of antenna designs, along with several different approaches to improve their overall performance, have given this book a great value, in which makes this book is deemed as a good reference for practicing engineers and under/postgraduate students working in this field. The key technology trends in antenna design as part of the mobile communication evolution have mainly focused on multiband, wideband, and MIMO antennas, and all have been clearly presented, studied and implemented within this book. The forthcoming 5G systems consider a truly mobile multimedia platform that constitutes a converged networking arena that not only includes legacy heterogeneous mobile networks but advanced radio interfaces and the possibility to operate at mm wave frequencies to capitalize on the large swathes of available bandwidth. This provides the impetus for a new breed of antenna design that, in principle, should be multimode in nature, energy efficient, and, above all, able to operate at the mm wave band, placing new design drivers on the antenna design. Thus, this book proposes to investigate advanced 5G antennas for heterogeneous applications that can operate in the range of 5G spectrums and to meet the essential requirements of 5G systems such as low latency, large bandwidth, and high gains and efficiencies

A four element stringray-shaped MIMO antenna system for UWB applications

This paper presents a CoPlanar-Waveguide (CPW)-fed stingray-shaped Ultra-WideBand (UWB) Multiple-Input–Multiple-Output (MIMO) antenna system designed for microwave imaging applications. Featuring a diagonal square with four inner lines and a vertical line at the center from toe to tip with a CPW feed line, the unit antenna element looks like a stingray fish skeleton and is, therefore, named as a stingray-shaped antenna. It offers a bandwidth spanning from 3.8 to 12.7 GHz. Fabricated on a 31mil RO5880 RF teflon substrate with a relative permittivity of 2.2, the proposed antenna has dimensions of 26 × 29 × 0.787 mm (Formula presented.). The maximum realized gain achieved is 3.5 dBi with stable omnidirectional radiation patterns. The antenna element is used in a four-antenna MIMO configuration with an isolation-improving structure at the center. The MIMO system has dimensions of 58 × 58 × 0.787 mm (Formula presented.) with a maximum realized gain of 5.3 dBi. The antenna’s performance in terms of MIMO parameters like Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) is within satisfactory limits for medical imaging applications. Time domain analysis also yields positive results, allowing its integration into a breast phantom tumor detection simulation. The simulation and measurement results demonstrate excellent agreement, making this antenna a promising candidate for microwave imaging and biomedical applications

Techniques for Compact Planar MIMO Antennas

MIMO Technology has promoted the developments of various antennas, then the planar antenna will be one of the main directions to satisfy the future compact requirement of the 5G+/6G communications. This chapter introduces different types of the planar antenna and summarizes the implicit compact techniques, where the related techniques like the diversity and the reconfigurable are not included owing to they are the inherent properties of the MIMO antennas. These antennas contain the patch antenna, slot antenna, dipole/monopole antenna, loop antenna, cavity antenna, Yagi-Uda antenna, fractal antenna, UWB antenna, PIFA etc., and their deformations to the specific purposes. On the contrary, the implicit compact techniques are not so explicit as the antenna configurations, but they are classified to be the close-spacing structure without decoupling, owing to the decoupling is not the necessary requirement of MIMO application, decoupling technique of spacing reduction, meandered line technique, multi-element method, co-radiator/co-location design, fractal antenna, and radiator-cutting antenna. Besides, the corresponding techniques for the compact design are also concluded, including the mode-cutting method, fractal technique, characteristic mode analysis, and the optimization algorithms

On the Feasibility of Multi-Mode Antennas in UWB and IoT Applications below 10 GHz

While on the one hand 5G and B5G networks are challenged by ultra-high data rates in wideband applications like 100+ Gbps wireless Internet access, on the other hand they are expected to support reliable low-latency Internet of Things (IoT) applications with ultra-high connectivity. These conflicting challenges are addressed in a system proposal dealing with both extremes. In contrast to most recent publications, focus is on the frequency domain below 10~GHz. Towards this goal, multi-mode antenna technology is used and different realizations, offering up to eight uncorrelated ports per radiator element, are studied. Possible baseband architectures tailored to multi-mode antennas are discussed, enabling different options regarding precoding and beamforming