Novel Nature-Derived Intelligent Algorithms and Their Applications in Antenna Optimization

With the rapidly developing of wireless communications, their adoption and utilization is increasing swiftly in various contexts. Among others, the issues relevant to antenna optimization are popularly known as the most important research subject for different wireless communications. Nowadays, a large number of studies have been published but spreading in a number of unrelated publishing directions which may hamper the use of such published resources. Furthermore, traditional approaches applied to this topic are normally based on simplified electromagnetic calculations which can only approximate real antenna performance. More recently, nature-inspired intelligent algorithms have become available to investigate antenna characteristics before construction. The advent of these algorithms has allowed different antenna design to be improved using mathematical optimization techniques. These provide us with the motivation of analyzing the existing studies in order to categorize and synthesize them in a meaningful manner.

Reconfigurable Antenna

Reconfigurable antennas have attracted a lot of attention especially in future wireless communication systems. Superior features such as reconfigurable capability, low cost, multi-purpose functions and size miniaturization have given reconfigurable antennas advantage to be integrated into a wireless systems. In this chapter, two types of reconfigurable antennas are discussed. First, frequency reconfigurable narrowband microstrip slot antenna (FRSA) is presented. The proposed antenna is designed to operate at six reconfigurable frequency bands from 2 GHz to 5 GHz with bidirectional radiation pattern. The second antenna design is frequency reconfigurable narrowband patch-slot antenna (FRPSA) is presented. The antenna is a combination of a microstrip patch and slot antenna. Nine different narrow bands are produced by tuning the effective length of the slot. The performances of the antenna in term of simulated and measured results are presented. In conclusion, good agreement between the simulated and measured results has been attained.

Reconfigurable Antennas

This chapter provides an overview of the demands in today's technologies and how reconfigurability contributes in a significant manner. After reviewing the mechanisms underlying the reconfigurability aspect of the antennas and identifying the challenges, the chapter provides all current techniques that are used to reconfigure the antenna parameters for different applications (frequency, radiation pattern, and polarization). Following the different methods and features characterizing the reconfigurability of antenna technologies, the chapter delves into the literature and provides an overview of the most promising techniques. Next, a comparative study of the aforementioned methodologies is given based on the fundamental reconfigurable principles and techniques. Closing this chapter, the auspicious approach of variable reactive loading is discussed. The proposed chapter aims at filling a gap in the literature and providing the readers (researchers, engineers and business organizations) with a useful reference.

Multiband Antenna for Modern Wireless Communication

Wireless technology lately became subjected to the rapid enormous changes in frequency allocation, policies and procedures of operations, and techniques in order to enhance the performance of the wireless system as whole. A lot of wired applications are converted into wireless, for example wired LAN is turned into a wireless, which due to the huge sophisticated researches. Currently due to the advanced of the integrated technology, engineers are able to fit many diversified applications working at different frequencies in one wireless device. Consequently an increased demand for multiple antennas covering different wireless communication bands on the same platform increased extremely.

Broadband Antennas

Apart from the sleeve monopole, this chapter discusses other broadband antennas as well, and the performance evaluation in terms of various measured and simulated parameters is also illustrated. This chapter will help antenna engineers get a better understanding of the antennas discussed and make a comparison with other broadband antennas. The broadband antennas that have been discussed in this chapter include: Low-profile sleeve monopole antenna, Dual-sleeve monopole antenna, Disc-conical sleeve monopole antenna, Wideband with dumbbell-shaped open sleeve antenna, Wideband unidirectional patch antenna with G-shaped strip feed, Wideband folded bowtie antenna with G-shaped strip feed and tuning stubs, Wideband bowtie antenna with inverted L-shaped coupling feed and tuning stubs.

Antenna System and Architecture-Circular Polarized UWB Antenna for Indoor Positioning Application

Indoor environment can be characterized as sever attenuating and depolarizing medium for electromagnetic (radio) waves propagation. These signals are radiated from transmitters to space (free-space propagation channel) and received from space to receivers through antennas. These signals are commonly radiated or received with pre-defined signal's polarization schemes and these schemes are always controlled by the antenna. In this chapter, the two-dimensional antenna designs and its polarization schemes are presented for minimizing the sever effects of an indoor environment. Emphasis is on understanding the special attention required for designing an antenna dedicated to an Indoor Positioning/Localization System. Some recent developments in antenna designs are presented as an example for the better understanding and its future perspective.

Reconfigurable Antennas for Cognitive Radio

With the development of the cognitive radio, that is a system (transceiver) aware of its own operational capabilities and needs which aims at a more efficient use of radio resources (e.g., more universal solution for the co-existence of multiple radio standards, but also limitation of electromagnetic radiations), the antennas with reconfiguration capabilities will become unavoidable. This chapter describes the different types of existing reconfigurable antennas and related approaches allowing the reconfiguration. The presentation relies on many examples from the literature and an example of designing a complete system of reconfigurable antenna frequency is finally detailed.

Limited Size MIMO Antenna Systems and Mutual Coupling Challenge

The wireless communication high data rate is achievable by installing more than one antenna in receiver and transmitter terminals as MIMO antenna. In order to obtain the MIMO gain (Envelope Correlation Coefficient (ECC) = 0.5), the antenna elements must be at least separated by a distance of 0.5? (? is the operating wavelength of 0.7~3.8 GHz which is the frequency range of most of the current wireless communication applications). This value is big relative to limited sizes devices. A practical MIMO antenna should have a low signal correlation between the antenna elements and good matching features for input impedance. Moreover, MIMO system performance can be improved by reducing mutual coupling between closely spaced antenna elements. Miniature high isolated MIMO antenna system has been presented in this chapter; also many MIMO antenna systems were analyzed and categorized based on the implemented isolation techniques. Furthermore several MIMO antenna evaluation methods have been discussed.

High-Gain Broadband Antennas for 60-GHz Short-Range Wireless Communications

This chapter introduces design and implementation of high-gain broadband antennas for 60-GHz short-range communications. It presents different antenna configurations and architectures that can be good candidates for the 60-GHz industrial, scientific and medical (ISM) band. Printed dipole array (PDA) antennas and especially the Printed log-periodic dipole array (PLPDA) antennas will be discussed in this chapter. Loading these kind of antennas with low-cost spherical or hemispherical dielectric lenses will also be presented and demonstrated to increase the gain of the antenna. Another type of antennas called electromagnetically coupled (EMC) elliptical patch antenna arrays will be investigated. Antipodal Vivaldi antenna and corrugated antipodal Vivaldi antenna are also introduced as good candidates for 60-GHz short-range communication applications.

Recent Trends in Antennas for Modern Wireless Communications

The rapid development in wireless communications has demanded multiband or wideband antennas to support wireless communication devices such as smart phones, tablets, laptop computers, radar system, satellite communication, airplane, and unmanned airborne vehicle (UAV) radar. It has also demanded compact wireless devices that allow more space to integrate other electronic components. The aim of this chapter is to provide an idea of current R&D trends and novel approaches in design, analysis and synthesis of broadband, multiband and reconfigurable antennas for the new generation of mobile communication devices, as well as for UWB communications, radars and so on.