Preface

**Chapter 8 131**

**Chapter 9 143**

Noise Characteristic Analysis of Multi-Port Network in Phased

Wearable Textile Antennas with High Body-Antenna Isolation:

*by Nikolay Atanasov, Gabriela Atanasova and Blagovest Atanasov*

Design, Fabrication, and Characterization Aspects

Array Radar *by Yu Hongbiao*

**II**

Recent developments in wireless communications such as 4G and the upcoming 5G cellular system, MIMO and massive MIMO, implantable and wearable systems, satellite, and radar systems, impose stringent design specifications and constraints. This book aims to present the latest developments in modern printed-circuit antennas written by experts in the field. This book consists of nine chapters. It is ideal for senior undergraduate students, graduate students, and engineers/researchers working in the field of antenna design.

Chapter One introduces a new concept to reduce mutual coupling among closelyspaced antenna elements of a MIMO array. This concept results in a significant reduction in the complexity of traditional approaches such as metamaterials, defected ground plane structures, parasitic elements, matching and decoupling networks using a planar metallic ring resonator printed on one face of an ungrounded substrate that surrounds a two-element vertical monopole antenna array. It is demonstrated both by simulations and measurements that the mutual coupling is reduced by at least 20 dB, maintaining the impedance bandwidth over which *S*<sup>11</sup> is less than 10 dB, and reducing the envelope correlation coefficient to below 0.001. The two vertical monopoles are operating at 2.4 GHz and separated by 8 mm (*λ*<sup>o</sup> /16), where *λ*<sup>o</sup> is the free-space wavelength at 2.45 GHz.

In Chapter Two, recent research advances on beamforming and spatial multiplexing techniques using reconfigurable metamaterials (MTMs) and metasurfaces are reviewed. This chapter describes basic principles of transmission line-based metamaterials and planar metasurfaces, followed by their active versions that enable novel smart antennas with beam steering and beamshaping functions. Detailed descriptions of their practical realizations and the integration with circuits and the radio-frequency (RF) frontend are also discussed. The latest metasurfacebased beamforming techniques are explained and compared for their uses in the RF-to-millimeter-wave range in terms of cost, reconfigurability, system integratability and radiation properties.

In Chapter Three a new ultrathin broadband reflected metasurface is proposed for applications involving high-gain planar antennas. A multilayer, multifunctional transmitted metasurface is next introduced to simultaneously enhance the gain and transform linear polarization to circular polarization of a patch antenna. This kind of high-gain antenna eliminates the feed-block effects of the reflected ones.

Chapter Four discusses how traditional size limitations can be overcome using a fractal geometry antenna. The shape is repeated into a limited size such that the total length of the antenna is increased to match, for example, half of the wavelength of the corresponding desired frequency. Many fractal geometries, e.g., the tree, Koch, Minkowski, and Hilbert fractals, are common. This chapter describes the details of designing, simulations, and experimental measurements of fractal antennas. Based on dimensional geometry in terms of desired frequency bands, the characteristics of each iteration are investigated in order to improve the antenna design process. The surface current distribution is analyzed to enhance the circular polarization radiation and axial ratio bandwidth. Simulation and experimental

results are compared. Two types of fractal antennas are reported, the first has a new structure configured via a five-stage process. The second has a low profile, wherein the configuration of the antenna was based on three iterations.

properties and resonant frequency, bandwidth, radiation efficiency, and maximum gain is presented. Finally, a case study is presented with detailed analyses and investigations of the low-profile all-textile wearable antennas with high bodyantenna isolation and low SAR. Their interaction with a semisolid homogeneous human body phantom is discussed. The simulations and experimental results from

I would like to gratefully acknowledge the Chair of the Systems Engineering Department, Dr. Ibrahim Nisnaci and Dr. Lawrence Whitman, Dean of the of Donaghey College of Science, Technology, Engineering, and Mathematics, University of Arkansas Little Rock for the encouragement they have offered throughout this project. Thanks are due to Dajana Pemac and Rebekah Pribetic, Author Service

**Dr. Hussain Al-Rizzo**

Little Rock, AR, USA

Professor of Electrical and Computer Engineering,

Donaghey College of Science, Technology, Engineering, and Mathematics,

Department of Systems Engineering,

University of Arkansas Little Rock,

different (in free-space and on-body) scenarios are presented.

Managers, IntechOpen for the expert assistance offered.

Chapter Five introduces several planar array designs based on the use of a small number of the active elements located at the center of the planar array surrounded by another layer of the uniformly distributed parasitic elements. The parasitic elements are used to modify the radiation pattern of the central active elements. The overall radiation pattern of the resulting planar array with a small number of active elements is comparable to that of the fully active array elements with a smaller sidelobe level at the cost of a relatively wider beamwidth and lower directivity. Nevertheless, the use of only a small number of the active elements provides a very simple feeding network that reduces the cost and the complexity of the array. The proposed array can be effectively and efficiently used in applications that require wider antenna beams.

Reconfigurable beam steering using a circular disc microstrip patch antenna with a ring slot is presented in Chapter Six. The dimension of the antenna is 5.4 5.4 mm<sup>2</sup> which is printed on a 0.504 mm thick, RT5870 substrate with relative permittivity 2.3 and loss tangent 0.0012. The antenna operates in the 60 GHz 5G frequency band. Two NMOS switches are utilized to generate three different beam patterns. Activating each switch individually results in a 70° shift in the main beam direction with constant frequency characteristics. The power gain is 3.9–4.8 dB in the three states of switch configurations. Simulated results in terms of return loss, peak gains, and radiation pattern are presented and reveal good performance for 5G applications.

In Chapter Seven, an ultra-wide band angular ring antenna that operated from 2.9 to 13.1 GHz is presented. The antenna has a nearly omni-directional radiation pattern for the E and H-plane at 3.5, 5.8, and 8.5 GHz. The theoretical analysis of the proposed antenna has been analyzed using circuit theory analysis. Measured, simulated, and analytical results compare well for reflection coefficient and radiation patterns. The proposed antenna is suitable for Wi-Fi, WiMax, digital communication system, satellite communication, and 5G applications.

Noise figure and noise power are analyzed and deduced in theory in Chapter Eight for multi-port networks in active phased array radar. The mathematical expressions of output noise power and noise figure of a network are provided under various conditions. Accordingly, this provides a basis of theories for a multi-port network and radar receiver system design, the test method of array noise figure. Two application examples are given to verify the accuracy of the formulas. Making use of these formulas, the designer can calculate the dynamic range of the radar receiver system, and the designer can also constitute a measure scheme of the array noise figure for active phased array radar.

Chapter Nine provides a brief overview of the types of wearable antennas possessing high body-antenna isolation. The main parameters and characteristics of wearable antennas and their design requirements are discussed. Next, procedures (passive and active) to test the performance of wearable antennas are presented. The electromagnetic properties of the commercially available textiles used as antenna substrates are investigated and summarized. This is followed by a more detailed examination of their effects on the performance of wearable antennas with high body-antenna isolation. A trade-off between substrate electromagnetic

properties and resonant frequency, bandwidth, radiation efficiency, and maximum gain is presented. Finally, a case study is presented with detailed analyses and investigations of the low-profile all-textile wearable antennas with high bodyantenna isolation and low SAR. Their interaction with a semisolid homogeneous human body phantom is discussed. The simulations and experimental results from different (in free-space and on-body) scenarios are presented.

I would like to gratefully acknowledge the Chair of the Systems Engineering Department, Dr. Ibrahim Nisnaci and Dr. Lawrence Whitman, Dean of the of Donaghey College of Science, Technology, Engineering, and Mathematics, University of Arkansas Little Rock for the encouragement they have offered throughout this project. Thanks are due to Dajana Pemac and Rebekah Pribetic, Author Service Managers, IntechOpen for the expert assistance offered.

> **Dr. Hussain Al-Rizzo** Professor of Electrical and Computer Engineering, Department of Systems Engineering, Donaghey College of Science, Technology, Engineering, and Mathematics, University of Arkansas Little Rock, Little Rock, AR, USA

results are compared. Two types of fractal antennas are reported, the first has a new structure configured via a five-stage process. The second has a low profile, wherein

Chapter Five introduces several planar array designs based on the use of a small number of the active elements located at the center of the planar array surrounded by another layer of the uniformly distributed parasitic elements. The parasitic elements are used to modify the radiation pattern of the central active elements. The overall radiation pattern of the resulting planar array with a small number of active elements is comparable to that of the fully active array elements with a smaller sidelobe level at the cost of a relatively wider beamwidth and lower directivity. Nevertheless, the use of only a small number of the active elements provides a very simple feeding network that reduces the cost and the complexity of the array. The proposed array can be effectively and efficiently used in applications that

Reconfigurable beam steering using a circular disc microstrip patch antenna with a ring slot is presented in Chapter Six. The dimension of the antenna is 5.4 5.4 mm<sup>2</sup> which is printed on a 0.504 mm thick, RT5870 substrate with relative permittivity 2.3 and loss tangent 0.0012. The antenna operates in the 60 GHz 5G frequency band. Two NMOS switches are utilized to generate three different beam patterns. Activating each switch individually results in a 70° shift in the main beam direction with constant frequency characteristics. The power gain is 3.9–4.8 dB in the three states of switch configurations. Simulated results in terms of return loss, peak gains, and radiation pattern are presented and reveal good performance for 5G

In Chapter Seven, an ultra-wide band angular ring antenna that operated from 2.9 to 13.1 GHz is presented. The antenna has a nearly omni-directional radiation pattern for the E and H-plane at 3.5, 5.8, and 8.5 GHz. The theoretical analysis of the proposed antenna has been analyzed using circuit theory analysis. Measured, simulated, and analytical results compare well for reflection coefficient and radiation patterns. The proposed antenna is suitable for Wi-Fi, WiMax, digital communica-

Noise figure and noise power are analyzed and deduced in theory in Chapter Eight for multi-port networks in active phased array radar. The mathematical expressions of output noise power and noise figure of a network are provided under various conditions. Accordingly, this provides a basis of theories for a multi-port network and radar receiver system design, the test method of array noise figure. Two application examples are given to verify the accuracy of the formulas. Making use of these formulas, the designer can calculate the dynamic range of the radar receiver system, and the designer can also constitute a measure scheme of the array noise

Chapter Nine provides a brief overview of the types of wearable antennas

high body-antenna isolation. A trade-off between substrate electromagnetic

possessing high body-antenna isolation. The main parameters and characteristics of wearable antennas and their design requirements are discussed. Next, procedures (passive and active) to test the performance of wearable antennas are presented. The electromagnetic properties of the commercially available textiles used as antenna substrates are investigated and summarized. This is followed by a more detailed examination of their effects on the performance of wearable antennas with

tion system, satellite communication, and 5G applications.

figure for active phased array radar.

the configuration of the antenna was based on three iterations.

require wider antenna beams.

applications.

**IV**

**1**

**Chapter 1**

Patterns

*and Samer Yahya*

**Abstract**

antenna element.

**1. Introduction**

Decoupled and Descattered

with Orthogonal Radiation

*Hussain Al-Rizzo, Ayman A. Isaac, Sulaiman Z. Tariq* 

This chapter introduces a novel design concept to reduce mutual coupling among closely-spaced antenna elements of a MIMO array. This design concept significantly reduces the complexity of traditional/existing design approaches such as metamaterials, defected ground plane structures, soft electromagnetic surfaces, parasitic elements, matching and decoupling networks using a simple, yet a novel design alternative. The approach is based on a planar single decoupling element, consisting of a rectangular metallic ring resonator printed on one face of an ungrounded substrate. The decoupling structure surrounds a two-element vertical monopole antenna array fed by a coplanar waveguide structure. The design is shown both by simulations and measurements to reduce the mutual coupling by at least 20 dB, maintain the impedance bandwidth over which *S*11, is less than −10 dB, and reduce the envelope correlation coefficient to below 0.001. The boresight of the far-field radiation patterns of the two vertical monopole wire antennas operating at 2.4 GHz and separated by 8 mm (*λ*o/16), where *λ*o is the free-space wavelength at 2.45 GHz, is shown to be orthogonal and inclined by 45° with respect to the horizontal (azimuthal) plane while maintaining the shape of the isolated single

**Keywords:** 4G/5G LTE/LTE-A, cellular communications, coplanar waveguide fed vertical monopole, decoupled antenna array, descattered antenna array, GPS,

Contemporary wireless systems including, but not limited to, 4G/5G LTE/LTE-A, radar, RFID, Wi-Fi, WiMAX, GPS, geolocation, biomedical imaging, and remote sensing dictate the use of miniaturized MIMO antenna arrays on mobile terminals. They can also be permanently installed on fixed structures for increased gain, which will improve link reliability and quality of service, increase communication range, and increase battery life through a variety of diversity schemes [1, 2], and/or increase data rate/throughput through MIMO spatial multiplexing schemes [3].

microstrip fed vertical monopole, MIMO, radar, RFID, Wi-Fi, WiMAX

Monopole MIMO Antenna Array

## **Chapter 1**
