Chapters authored
Multiband Planar Antennas for Broadband Wireless Systems
Next generation of wireless mobile systems calls for more compact and multiband antennas. This is because such systems need to be small and can operate over multiple wireless communication standards. The design and development of miniature antennas that function over a wideband are highly challenging. In this chapter, novel antenna designs are presented, which provide a solution to this deficiency. These antennas are based on composite right‐/left‐handed transmission line (CRLH‐TL) metamaterials. Unlike traditional right‐handed (RH) transmission materials, metamaterials based on left‐handed (LH) transmission lines have unique features of antiparallel group and phase velocities. Pure LH transmission lines cannot be implemented due to the existence of RH parasitic effects that occur naturally in practical LH transmission lines. In this chapter, novel CRLH transmission line structures are presented, which include right‐handed parasitic effects.
Part of the book: Microwave Systems and Applications
Compact Planar Antennas for Beam Steering and RFID Tags
The chapter presents innovative planar antennas for beam steering and radio frequency identification (RFID) applications. Beam steering has become vital in commercial wireless communications, including mobile satellite communications where high data rate communication is required. The chapter describes a low-cost beam-steering antenna based on a leaky-wave antenna structure that is capable of steering the main radiation beam of the antenna over a large range from −30° to +15°. Interest in RFID systems operating in the ultrahigh frequency (UHF) is rapidly growing as it offers benefits of long read range and low cost, which make it an excellent system for use in distribution and logistics systems. This chapter presents a technique of overcoming the limitations of conventional HF coils in RFID tags where the total length of the spiral antenna is restricted inside the available area of the tag.
Part of the book: Microwave Systems and Applications
Metamaterial Antennas for Wireless Communications Transceivers
Limited space is given to antennas in modern portable wireless systems, which means that antennas need to be small in size and compact structures. However, shrinkage of conventional antennas leads to performance degradation and complex mechanical assembly. Therefore, the design of miniature antennas for application in wireless communication systems is highly challenging using traditional means. In this chapter, it is shown that metamaterial (MTM) technology offers a solution to synthesize antennas with a small footprint with the added advantage of low cost and excellent radiation characteristics.
Part of the book: Modern Antenna Systems
Planar Antennas with Enhanced Bandwidth and Radiation Characteristics
Wireless companies want next-generation gadgets to download at rates of gigabits per second. This is because there is an exponential growth in mobile traffic, however, existing digital networks and devices will not be efficient enough to handle this much growth. In order to realize this requirement, the next generation of wireless communication devices will need to operate over a much larger frequency bandwidth. In this chapter, novel wideband and ultra-wideband (UWB) antennas that are based on loading the background plane of a monopole radiator with concentric split-ring resonators are presented. It is shown that this modification improves the fractional bandwidth of the antenna from 41 to 87%; in particular, the operational bandwidth of the proposed antennas is double that of a conventional monopole antenna of the same size.
Part of the book: Modern Antenna Systems
Planar Antennas for Reliable Multiband RF Communications
Multiband functionality in antennas has become a fundamental requirement to equip wireless devices with multiple communication standards so that they can utilize the electromagnetic spectrum more efficiently and effectively. This is necessary to ensure global portability and enhance system capacity. To meet these requirements, microstrip technology is increasingly being used in communication systems because it offers considerable size reduction, cost-effectiveness as they can be easily manufactured in mass production, are durable and can conform to planar or cylindrical surfaces. Unfortunately, such antennas suffer from intrinsically narrow bandwidth. To overcome this deficiency, various techniques have been investigated in the past. In this chapter, a novel approach is presented to design antennas for applications that cover radio frequency identification (RFID) and WiMAX systems.
Part of the book: Metamaterials
Metamaterial Based Ultra-Wideband Antennas for Portable Wireless Applications
Antennas are essential for wireless communication systems. The size of a conventional antenna is dictated mainly by its operating frequency. With the advent of ultra-wideband systems (UWB), the size of antennas has become a critical issue in the design of portable wireless devices. Consequently, research and development of suitably small and highly compact antennas are challenging and have become an area of great interest among researchers and radio frequency (RF) design engineers. Various approaches have been reported to reduce the physical size of RF antennas including using high permittivity substrates, shorting pins, reactive components, and more recently, metamaterials (MTM) based on composite right-/left-handed transmission-lines (CRLH-TLs). MTM exhibit unique electromagnetic response that cannot be found in the nature. In this chapter, the properties of CRLH-TL are used to synthesize novel and highly compact planar UWB antennas with radiation properties suitable for wireless mobile devices and systems.
Part of the book: Metamaterials
Miniature Planar Antenna Design for Ultra-Wideband Systems
Demand for antennas that are compact and operate over an ultra‐wideband (UWB) frequency range is growing rapidly as UWB systems offer high resolution imaging capability and high data rate transmission in the order of Gb/s that is required by the next generation of wireless communication systems. Hence, over the recent years the research and development of UWB antennas has been widely reported in literature. The main performance requirements sought from such antennas include: (1) low VSWR of <2; (2) operation over 7.6 GHz from 3 to 10.6 GHz; and (3) good overall radiation characteristics. Significant size reduction and low manufacturing cost are also important criteria in order to realize a cost‐effective and miniature system. Other desirable requirements include compatibility and ease of integration with RF electronics.
Part of the book: Microstrip Antennas
Printed Planar Antenna Designs Based on Metamaterial Unit- Cells for Broadband Wireless Communication Systems
View all chaptersWith the continuing development of mobile communications, the communication standards, which include operating frequencies and protocols, are also evolving. In order to accommodate these and future changes, antennas with characteristics of wideband and multiband are becoming a necessity. Hence, wireless communications industries are now demanding broadband antennas that are low-profile and low-volume structures. Conventional planar microstrip antennas are the most common form of printed antennas that have been used for many years. This is because these antennas offer advantages of low cost, conformability, and ease of manufacturing; however, the bandwidth of these types of antennas is highly restricted. Among different types of planar antennas, the slotted structure that offers the simplest structure is compact and radiates omnidirectionally; these features make it an excellent candidate for broadband applications.
Part of the book: Microstrip Antennas