The Design And Analysis Of Electrically Small Antennas Utilizing Top Loading For Optimized Wireless Communications

Author's abstract: With the advancement, availability, and the convenience of wireless technologies wireless networks are becoming common practice for households and companies. There is an inherent need to maintain these wireless networks secure because of personal or sensitive material that is transmitted over wireless mediums. Novel antenna designs that reduce the antenna size allow for uses in both the medical and cybersecurity domains. A wireless security zone can be created if directional wide beamwidth antennas are placed in an outward facing manner transmitting noise, then the area inside the outward facing antennas will be secure due to the fact that any intruder would only be able to detect the noise or false data. Continued security improvements can be made by controlling the internal network coverage area with directional antennas and variable use of transmitted power. The results are conclusive with the testing that has been done to ensure a secure wireless network.

As the demand for compact, portable communication electronics increases, the technology of miniaturization has made great progress. A beneficiary of that progress has been research into new concepts for the antenna, one of the essential components in wireless communications. As the size of an antenna becomes smaller, however, the antenna suffers from high Q and low radiation resistance. The results are narrow bandwidth, poor matching, low efficiency, and, more generally, poor performance throughout the communication system. First, the design of a small antenna for HF/VHF communications is described. As the operating frequency of an antenna decreases, for example, into the HF and low VHF regions, the physical size of the antenna becomes a critical issue. It is desirable to design a truly electrically small antenna by reducing the ground plane size. Moreover, when the antenna size is very small, the bandwidth of the antenna is extremely narrow, which is critical to various deployment variances and propagation effects such as multi-path fading. The new design, which is an inductively coupled, top-loaded, monopole structure optimized by a genetic algorithm (GA), maximizes transmission of HF/VHF waves. Electrically small, spiral ground planes for the monopole and the electrically small antenna are designed for HF ground-wave transmission. In addition, a tunable small antenna is investigated that overcomes the narrow-bandwidth limitation of electrically small antennas. Second, new design methodologies for electrically small antennas are discussed. Use of an inductively coupled feed is one of the well-known methods for boosting input resistance. As the antenna size becomes smaller, however, it is found that the efficiency of an antenna using an inductively coupled feed is lower than an antenna using multiple folds. After a comparison of the two methods, the design of a thin, multiply folded, electrically small antenna is proposed for achieving high efficiency in a physically compact size. The GA is used to assess the effect of geometry on the performance (in terms of efficiency and bandwidth) of the electrically small antennas, including the folded conical helix and folded spherical helix. Finally, the prospects of using the new Yagi antennas to achieve small size are explored. Yagi antennas are used widely to obtain high gain in a simple structures. The antenna is composed of the driven element and the parasitic elements, which include a reflector and one or more directors. Typically, sufficient spacing on the order of 0.15[lambda] to 0.4[lambda] between the driven element and the parasitic elements is needed for the Yagi antenna to operate well. For some applications, however, it is desirable to reduce the spacing and the length of the elements to achieve a physically more compact size. In this dissertation, closely spaced, folded Yagi antennas in both three dimensions and two dimensions are investigated, and a design for an electrically small Yagi antenna is suggested.

Author's abstract: A growing need for efficient wireless communication is prevalent in the world in which we live. From cell phones to television to GPS applications, wireless communications are vital in consumer electronics and military applications. In these applications, a miniaturized antenna is sometimes necessary for reducing overall size of the communication system. For many satellite based communication applications, circular polarization in antennas is needed for efficient communication. In this thesis, the miniaturization technique known as T-top loading is utilized on two novel antenna designs. One design is an electrically small, circularly polarized planar cross dipole and the other design is a compact circularly polarized log-periodic dipole array. Both antennas are designed in simulation software with the intent for prototype fabrication for measurement verification of simulation results.

Modern society thrives on communication that is instant and available at all times, a constant exchange of information that encompasses everything from video streaming to GPS navigation. Experts even suggest that in the near future everything from our cars to our kitchen appliances will be connected to the internet, a feat that would not be possible without advanced wireless technology. Wideband, Multiband, and Smart Reconfigurable Antennas for Modern Wireless Communications showcases current trends and novel approaches in the design and analysis of the antennas that make wireless applications possible, while also identifying unique integration opportunities for antennas and wireless applications to work together. By featuring both theoretical and experimental approaches to integration, this book highlights specific design issues to assist a wide-range of readers including students, researchers, academics, and industry practitioners. This publication features chapters on a broad scope of topics including algorithms and antenna optimization, wireless infrastructure development, wireless applications of intelligent algorithms, antenna architecture, and antenna reconfiguration techniques.

Compact Antennas for Wireless Communications and Terminals deals with compact microwave antennas and, more specifically, with the planar version of these antennas. Planar antennas are the most appropriate type of antenna in modern communication systems and more generally in all applications requiring miniaturization, integration and conformation such as in mobile phone handsets. The book is suitable for students, engineers and scientists eager to understand the principles of planar and small antennas, their design and fabrication issues, and modern aspects such as UWB antennas, reconfigurable antennas and diversity issues.

If you are involved in designing and developing small antennas, this complete cutting-edge guide covers everything you need to know. From fundamentals and basic theory to design optimization, evaluation, measurements and simulation techniques, all the essential information is included. You will also get many practical examples from a range of wireless systems, whilst a glossary is provided to bring you up to speed on the latest terminology. A wide variety of small antennas is covered, and design and practice steps are described for each type: electrically small, functionally small, physically constrained small and physically small. Whether you are a professional in industry, a researcher, or a graduate student, this is your essential guide to small antennas.

With the progress and rapid increase in mobile terminals, the design of antennas for these small systems is becoming more and more important. This forward-looking volume offers professionals current and comprehensive coverage of the design, development, and implementation of small, compact, and lightweight antennas in mobile communication terminals. The book discusses a wide range of communication systems, from Radio-frequency identification (RFID), and near field communications (NFC), to wireless power transmission (WPT) and broadband wireless networks. Engineers learn how to use small antennas in mobile phones, wearable systems, laptop computers, radio watches, and broadband wireless networks such as WLAN and WiMAX. This definite reference covers the critical applications today’s professionals need to understand, from antennas for IoT and antenna design for 5G mm-wave devices, to body-centric communication systems and antennas for unmanned aerial vehicles.

Global wireless communications networks are facing an ever increasing demand to deliver content to the consumer. Along with increased consumption of wireless bandwidth, consumers demand that their devices interface with a plethora of different wireless bands and protocols. To meet this demand, mobile devices have a multiplicity of antennas designed to work for specific bands. However, as mobile communication demands continue to grow, the number of antennas will become even more constrained by size and cost. In order to address this issue, an inductively loaded, electrically small, frequency reconfigurable, sector antenna that covers most consumer frequency bands has been developed. This thesis details the design and characterization of the antenna element, which tunes the GSM 900, GSM 1800, 3G, WiFi, and WiMAX bands. The antenna developed is modified from a previous design for frequency reconfiguration using varactor diodes placed in inductive loads. In order to allow for frequency agility, a DC bias network is carefully designed utilizing blocking capacitors to allow for an impedance match over the bands of interest. Characterization of the antenna on different ground plane sizes and construction issues are also addressed. Finally the inductively loaded, electrically small, frequency reconfigurable, sector antenna is fabricated and measured to confirm the simulation analysis. Comments on the radiation patterns, efficiency, and gain are also provided.

Complete and comprehensive application-focused reference on millimetre wave antennas Millimetre Wave Antennas for Gigabit Wireless Communications covers a vast wealth of material with a strong focus on the current design and analysis principles of millimetre wave antennas for wireless devices. It provides practising engineers with the design rules and considerations required in designing antennas for the terminal. The authors include coverage of new configurations with advanced angular and frequency filtering characteristics, new design and analysis techniques, and methods for filter miniaturization. The book reviews up-to-date research results and utilizes numerous design examples to emphasize computer analysis and synthesis whilst also discussing the applications of commercially available software. Key Features: Advanced and up-to-date treatment of one of the fastest growing fields of wireless communications Covers topics such as Gigabit wireless communications and its required antennas, passive and active antenna design and analysis techniques, multibeam antennas and MIMO, IEEE 802.15.3c, WiMedia®, and advanced materials and technologies Offers a practical guide to integrated antennas for specific configurations requirements Addresses a number of complex, real-world problems that system and antenna engineers are going to face in millimetre-wave communications industry and provides solutions Contains detailed design examples, drawings and predicted performance This book is an invaluable tool for antenna professionals (engineers, designers, and developers), microwave professionals, wireless communication system professionals, and industries with microwave and millimetre wave research projects. Advanced students and researchers working in the field of millimetre wave engineering will also find this book very useful.

Author's abstract: Electronic sizes are constantly decreasing. The need for smaller communication systems is at an all-time high. The antenna is a major part of wireless communication systems, so the need for smaller antennas is also paramount. Electrically-small antennas are the solution to this problem. Electrically-small antennas have many inherent limitations. In this thesis, a comprehensive background on electrically-small antennas is conducted to illustrate the common design limitations that face electrically-small antennas. Three novel, size-reduced antennas are presented in this thesis. A 15-element size-reduced Yagi-Uda antenna, a 6-element size-reduced antenna, and a spherical helix electrically-small antenna are all introduced in this thesis. The antennas are all designed, simulated, fabricated, and measured for verification of results.