Band-Notch Characteristics in Ultra-Wideband Antennas

Taimoor Khan, Yahia M.M. Antar

• Publisher: CRC Press
• Year: 2021
• Print ISBN: 9780367754723
• eBook ISBN: 9781000384024
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

This book comprehensively reviews ultra-wideband (UWB) and UWB multi-input multi-output (MIMO) antennas with band-notched characteristics, with a focus on interference cancellation functionality. The book is organized into seven chapters that cover single band, dual band, and multi band-notched UWB antennas, followed by band-notched characteristics in UWB (MIMO) antennas. Further, it explains the mechanism of reconfigurability and tunability in band-notched UWB antennas, including advanced applications of UWB systems. Overall, it covers different techniques of canceling the electromagnetic interference in UWB in a concise volume.

Features

• Provides a comprehensive presentation of avoiding interference in UWB systems
• Reviews state of the art literature related to UWB antennas, filtennas, and various reconfigurable technologies
• Explains different techniques for producing band-notch characteristics in UWB systems
• Includes discussion on historical perspectives of UWB technology
• Consolidates different research activities carried out on the electromagnetic interference cancellation techniques in the UWB communication systems

Band-Notch Characteristics in Ultra-Wideband Antennas is aimed at researchers and graduate students in electrical and antenna engineering.

Taimoor Khan has been an Assistant Professor at the Department of Electronics and Communication Engineering, National Institute of Technology Silchar since 2014. In addition to this, Dr. Khan has also worked as a Visiting Assistant Professor at Asian Institute of Technology Bangkok, Thailand during September–December, 2016. His active research interests include Printed Microwave Circuits, Electromagnetic Bandgap Structures, Ultra-wideband Antennas, Dielectric Resonator Antennas, Ambient Microwave Energy Harvesting, and Artificial Intelligence Paradigms in Electromagnetics. Dr. Khan has successfully guided three Ph.D. theses, and is supervising six Ph.D. students. He has published over 75 research articles in well-indexed journals and in world-renowned conference proceedings. Currently, he is executing three funded research projects, including two international collaborative SPARC and VAJRA research projects. In September 2020, Dr. Khan has been awarded a prestigious national IETE-Prof SVC Aiya Memorial Award for the year 2020.

Yahia M. M. Antar has been a Professor at the Department of Electrical and Computer Engineering, Royal Military College of Canada since 1990. He served as the Chair of CNC, URSI from 1999 to 2008, Commission B from 1993 to 1999, and has a cross appointment at Queen's University in Kingston. He has authored and co-authored over 250 journal papers, several books and chapters in books, over 500 refereed conference papers, holds several patents, has chaired several national and international conferences, and has given plenary talks at many conferences. Dr. Antar is a fellow of the Engineering Institute of Canada, the Electromagnetic Academy, and an International Union of Radio Science (URSI). He was elected by the URSI to the Board as the Vice President in 2008 and in 2014, and to the IEEE AP AdCom in 2009. In 2011, he was appointed as a member of the Canadian Defence Advisory Board (DAB) of the Canadian Department of National Defence. He serves as an Associate Editor for many IEEE and IET Journals, and as an IEEE-APS Distinguished Lecturer. Presently, he is working as President-Elect for IEEE Antenna and Propagation Society for the year 2020.

1

Band-Notched UWB Antennas

1.1 Introduction

Advancement in wireless technology has altered our lives in the past few decades. The technological enhancements have allowed us to avail new services for mobile communication such as voice, audio, video, and data services. Further, it has also helped us in accomplishing a faster data rate between portable devices and computers within a short range. This high-speed data rate can be enlarged by increasing the transmission power or employment of wide bandwidth. However, many portable devices operating with wireless technology are battery-powered, thus a large frequency bandwidth will be the solution for achieving high data rate [1]. In this perspective, ultra-wideband (UWB) technology is a revolutionary approach in the field of wireless communication due to its high-speed data rate and excellent immunity to multi-path interference. The UWB research field has received great amount of interest since the decision by the Federal Communications Commission (FCC) in February 2002 authorizing the emission of very low-power spectral density in a bandwidth of 7.5 GHz going from 3.1 GHz to 10.6 GHz [2, 3]. Since then, UWB technology has been considered as one of the most promising technologies used in various applications such as radar, sensing, and military communications [4].

In the development of UWB communication system, an antenna plays a significant role. Thus, a practical UWB antenna should be designed with better impedance matching, compact size, low cost, omni-directional radiation pattern, and flat group delay over the UWB region [5]. Among different type of antennas, printed antennas are usually preferred for UWB technology-based communication systems because of their compact size, low profile, and easy integration facilities. These antennas help to make the system more robust and also reduce the implementation cost. Therefore, much effort has been devoted to the design of printed UWB antennas [6]. However, an underlying challenge in UWB antenna is to avoid interference due to some existing technologies that share the frequency bands within the UWB regulation standards. These are Worldwide Interoperability for Microwave Access (WiMAX) (3.3–3.7 GHz band), Wireless Local Area Network (WLAN) (5.15–5.35 GHz and 5.725–5.825 GHz bands), C-band satellite downlink (7.25–7.75 GHz band), X-band (8.025–8.4 GHz band), etc. Thus, it is essential to reject the interference with the existing wireless technologies.

In order to investigate different techniques developed for introducing notched behavior in UWB antennas, a review has been carried out in this chapter based on the publications available in literature [7–100]. The authors have tried to bring the developments that have taken place related to designing of band-notched antennas in past few years and also to acknowledge the novel contribution of the researchers. The organization of this chapter has been done as follows: Section 1.1 describes the concept of band-notch in UWB antennas. Section 1.2 analyzes UWB antennas with single notch [7–37] characteristics followed by analysis of dual [38–57] and multi- [58–74] notch antennas in Section 1.3 and Section 1.4, respectively. The discussion also includes description of different reconfigurable and tunable configurations with notched bands in Section 1.5 [75–90]. Further, Section 1.6 [91–100] describes UWB band-notch multi-input multi-output (MIMO) antennas. A summary of this review process is highlighted in Section 1.7. Finally, Section 1.8 presents conclusion for this chapter, followed by the list of references.

1.2 Concept of Band-Notched Filtering in UWB Antennas

As mentioned in Section 1.1, UWB systems cover a wide frequency range, and thus, they interfere with the existing narrow-band communication systems. To address the interference problem in UWB communication, it is necessary to filter out the overlapping bands. The traditional method that is followed to suppress such potential interferences is to connect the antenna with narrow-band band-stop filters [101]. Figure 1.1 describes such a frequency notched antenna system.

FIGURE 1.1 Notched ultra-wideband antenna system using bandstop filter.

The spectral response of band-stop filter reveals that it allows UWB frequency range (Figure 1.2(a)) to pass except at two frequencies (f₁ and f₂). Thus, these two frequencies are notched out in the spectral response of UWB system, as shown in Figure 1.2(b). However, such an approach fails to achieve compactness and, at the same time, increases complexity and cost of the radio-frequency (RF)-front-end systems [102]. Thus, UWB antennas with band-rejection functions inherited in it are preferred. Such types of antennas are developed by introducing narrow-band resonant structures in them [103].

FIGURE 1.2 Development of frequency notched system using bandstop filters in terms of spectral response (a) ultra-wideband (UWB) antenna and (b) notched UWB system.

The addition of resonant structures results in band-notched characteristics in two ways. First, the impedance matching gets degraded by installing the resonant configuration, resulting in less energy transmission into/reception from the free space. Second, the current distribution on the antenna gets changed as a result of the addition of resonant structure, which may cause the canceling of radiation in the far-field zone [104]. Various techniques, thus, have been proposed to realize such resonant structures for notch characteristics which have been comprehensively analyzed in subsequent sections.

1.3 Single Band-Notched Characteristics

UWB antennas with single band-rejection characteristics are designed to avoid interference from the existing different narrow-band radio technologies operating at frequencies covered by the UWB band or its nearby frequencies. Different methods such as using slotted radiating or ground surface [7–23], placing parasitic patches [24–27] or installing open-ended stubs to the radiating patch [28–31], using electromagnetic bandgap (EBG) structure [32, 33], and multiple other techniques [34–37] have been proposed for obtaining single band-notched characteristics. One of the common techniques for developing notch performance is to embed slotted geometry in the antenna structure which changes the current flow, thereby resulting in a notch at a particular frequency. Some V-shaped slotted radiating surface-based monopole antenna geometries such as those discussed in [7, 8] and [9] have been proposed for generating single band-notched characteristics. Again, U-shaped slotted radiating surface-based monopole antennas, as given in [10-14] are suggested for rejecting different bands, respectively. In [10], a second configuration of notched antenna is proposed with C-shaped slot. There are some other C-shaped slotted radiating surface-based monopole antennas as discussed in [15, 16]. In [17], a second configuration has also been proposed by implementing half wavelength ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• List of Figures
• List of Tables
• Preface
• Acknowledgement
• 1 Band-Notched UWB Antennas
• 2 Single Band-Notched UWB Antennas
• 3 Dual Band-Notched UWB Antennas
• 4 Multi Band-Notched UWB Antennas
• 5 Band-Notched UWB MIMO Antennas
• 6 Reconfigurable Band-Notched UWB Antennas
• 7 Tunable Band-Notched UWB Antennas
• Index