Dual Band-Notched Microstrip-Fed Vivaldi Antenna Utilizing Compact EBG Structures

We propose an ultra-wideband (UWB) antipodal Vivaldi antenna (AVA) with high-Q stopband characteristics based on compact electromagnetic bandgap (EBG) structures. First, an AVA is designed and optimized to operate over an UWB spectrum. Then, two pairs of EBG cells are introduced along the antenna feed line to suppress the frequency components at 3.6–3.9 and 5.6–5.8 GHz (i.e., WiMAX and ISM bands, resp.). Simulated and measured results show a voltage standing wave ratio (VSWR) below 2 for the entire 3.1–10.6 GHz band with high attenuation at the two selected subbands. This simple yet effective approach eliminates the need to deform the antenna radiators with slots/parasitic elements or comprise multilayer substrates. Furthermore, the flexibility it offers in terms of controlling both the number and locations of the band-reject frequencies is advantageous for antennas with nonuniform flares as in the AVA

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

A parasitic patch loaded staircase shaped UWB MIMO antenna having notch band for WBAN applications

A staircase-shaped quasi-fractal antenna is presented to meet the requirements of compact electronics operating in UWB or E-UWB spectrum. A conventional broadband monopole antenna is converted into UWB antenna utilizing three iterations of fractal patches. The resultant antenna offers wide impedance bandwidth ranges 2.3–17.8 GHz, having a notch band at 6.1–7.2 GHz. Afterwards, a two-port MIMO antenna is created by placing the second element orthogonally with an edge-to-edge distance of 8.5 mm, that is λ/15 where λ corresponds to free space wavelength at the lowest cut-off frequency. Hereafter, a meandered line-shaped stub is inserted to reduce the mutual coupling between closely spaced MIMO elements to less than −25 dB. As the intended application of the proposed work is On-body, Specific Absorption Rate (SAR) analyses are carried out at 2.4, 5.8 and 8 GHz, showing an acceptable range for both 1-g and 10-g averaged tissues standards. Moreover, various parameters of the MIMO antenna are studied, and a comparison is made between simulated and measured results as well as those of the state of the art

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Harmonic Suppressed Reconfigurable Dual-band, Multi-mode Ultra-wideband, and Compact High Selective Microstrip Bandpass Filters

As an indispensable component, microwave bandpass filters play a very important role in many modern wireless systems. They are used to carry out the selection of only the wanted frequencies from RF signals with various spurious frequencies. The reconfigurable filter with multi-band has attracted much attention for both research and industry because of the increasing importance in making RF components that have multi-function with compact size. Wide or Ultra-wideband (UWB) bandpass filters are becoming more and more in demand in many wireless applications due to the high data transmission rate. This dissertation focuses on the study of microwave filters with many applications in various wireless systems. Firstly, bandpass filters using stepped impedance stubs are presented. The resonant frequencies and transmission zeros are analyzed, and harmonic suppression by novel S-shaped coupled feed lines is presented. A resonator with a dual-band characteristic is introduced, and it is analytically shown that each passband can be independently controlled by the parameters of the resonator. PIN diodes are used to introduce an electrically controlled dual-band bandpass filter. Secondly, symmetric stepped impedance resonators with asymmetric stepped impedance stubs are also presented to develop Ultra-wide band (UWB) bandpass filters with and without a notched band. The resonant frequencies and transmission zeros of the resonator are effectively located to achieve a very wide passband and a high attenuation rate in rejection bands. The interdigital coupled feed lines with rectangular slots are designed for a better passband characteristic. A notched characteristic is introduced by using modified feed lines to avoid the interferences with other existing signals. UWB bandpass filter performances in time-domain and frequency-domain are analyzed and discussed. Thirdly, UWB bandpass filters with a different configuration are developed. Similarly, the analyzed resonant frequencies are used to achieve a passband for UWB applications. A different technique is used to introduce a very narrow notched band within the passband. Time-domain analysis is made to verify the frequency-domain performance. Lastly, a very high selective wideband bandpass filter is presented using an inverted T-shaped resonator. The characteristic of the resonator is analyzed to design a bandpass filter with specified bandwidth. The short stubs are introduced to achieve a very high attenuation rate at both sides of the passband and a wide stopband characteristic. In summary, various microwave filters to meet the requirements of specific applications are studied and designed. Analysis and design methodology of the proposed microwave filters in this dissertation can be applied in many applications in wireless systems

Recent Advances in Antenna Design for 5G Heterogeneous Networks

The aim of this book is to highlight up to date exploited technologies and approaches in terms of antenna designs and requirements. In this regard, this book targets a broad range of subjects, including the microstrip antenna and the dipole and printed monopole antenna. The varieties of antenna designs, along with several different approaches to improve their overall performance, have given this book a great value, in which makes this book is deemed as a good reference for practicing engineers and under/postgraduate students working in this field. The key technology trends in antenna design as part of the mobile communication evolution have mainly focused on multiband, wideband, and MIMO antennas, and all have been clearly presented, studied and implemented within this book. The forthcoming 5G systems consider a truly mobile multimedia platform that constitutes a converged networking arena that not only includes legacy heterogeneous mobile networks but advanced radio interfaces and the possibility to operate at mm wave frequencies to capitalize on the large swathes of available bandwidth. This provides the impetus for a new breed of antenna design that, in principle, should be multimode in nature, energy efficient, and, above all, able to operate at the mm wave band, placing new design drivers on the antenna design. Thus, this book proposes to investigate advanced 5G antennas for heterogeneous applications that can operate in the range of 5G spectrums and to meet the essential requirements of 5G systems such as low latency, large bandwidth, and high gains and efficiencies

Miniaturised and reconfigurable planar filters for ultra-wideband applications

An increasing demand for electromagnetic spectrum has resulted from the emergence of feature-rich and faster throughputs wireless applications. This necessitates the developments of dynamic reconfigurable or multifunctional systems to better exploit the existing spectrum. Future wireless devices will be expected to communicate over several bands with various other devices in order to fine tune the services they provide to the user. Each band may require a separate RF transceiver and such modern wireless multi-band multi-mode communication systems call for high performance, highly integrated compact modules. Since the Federal Communications Commission (FCC) released the unlicensed frequency band 3.1-10.6 GHz for ultra-wideband (UWB) commercial communications, the development race for commercialising UWB technology has seen a dramatic increase around the world. The aim of this research is to develop reconfigurable planar microwave filters for ultrawideband applications. The project investigates some key design issues of reconfigurable filters, which are being observed constantly in the latest development and realisation of microwave filters. Both analytical and numerical methods are performed to construct a realistic and functional design. Two different types of frequency reconfigurability are investigated in this thesis: discrete (e.g. PIN diode, Optical switch) and continuous (e.g. varactor diode). Using the equivalent circuits and considering the direct coupled filter structure in most cases, several topologies with attractive features are developed for future communication systems. The proposed works may be broadly categorised into three sections as follows. The first section explores a square ring shape close loop resonator along with an opencircuited stub in the symmetry plane. To realise a reconfigurable frequency states within the same spectrum, an innovative approach is developed for this case. An optical or photoconductive switch, comprised of a silicon die activated using near infrared light is investigated as a substitute of PIN diode and performances are evaluated to compare the feasibilities. In addition, a in-band interference rejection technique via externally coupled Tshape resonator is shown. However, it is observed that both structures achieve significant size reductions by utilising the inner part of the resonators. To improve the filter selectivity, a convenient design approach generating a pair of transmission zeros between both passband edges and a single zero in the stop band for harmonic suppression is discussed in the second section. Moreover, the development of notched rejection bands are studied and several novel methods to create a single and multiple notched bands employing the square ring shape structure are proposed. On inspection, it is found that the notch structure can be implemented without deteriorating the filter performances. The discussions are supplemented with detailed design examples which are accompanied by theoretical, simulated and experimental results in order to illustrate the filter development process and showcase practical filter performance. The third section reveals a novel highly compact planar dual-mode resonator with sharp rejections characteristics for UWB applications. A bandwidth reconfiguring technique is demonstrated by splitting its even-mode resonance. Filter structure with the dual-mode resonator is shown to have a relatively wide tuning range, significantly low insertion loss and a constant selectivity along with frequency variations in comparison to similar published works. Finally, the earlier dual-mode structure are modified to realise a dual wideband behaviour. A detail analysis with comprehensive design procedures is outlined and a solution for controlling the frequency bandwidths independently according to the application interest is provided. In line with the previous section, experimental verification is presented to support and supplement the discussions

Harmonic Suppressed Reconfigurable Dual-band, Multi-mode Ultra-wideband, and Compact High Selective Microstrip Bandpass Filters

As an indispensable component, microwave bandpass filters play a very important role in many modern wireless systems. They are used to carry out the selection of only the wanted frequencies from RF signals with various spurious frequencies. The reconfigurable filter with multi-band has attracted much attention for both research and industry because of the increasing importance in making RF components that have multi-function with compact size. Wide or Ultra-wideband (UWB) bandpass filters are becoming more and more in demand in many wireless applications due to the high data transmission rate. This dissertation focuses on the study of microwave filters with many applications in various wireless systems. Firstly, bandpass filters using stepped impedance stubs are presented. The resonant frequencies and transmission zeros are analyzed, and harmonic suppression by novel S-shaped coupled feed lines is presented. A resonator with a dual-band characteristic is introduced, and it is analytically shown that each passband can be independently controlled by the parameters of the resonator. PIN diodes are used to introduce an electrically controlled dual-band bandpass filter. Secondly, symmetric stepped impedance resonators with asymmetric stepped impedance stubs are also presented to develop Ultra-wide band (UWB) bandpass filters with and without a notched band. The resonant frequencies and transmission zeros of the resonator are effectively located to achieve a very wide passband and a high attenuation rate in rejection bands. The interdigital coupled feed lines with rectangular slots are designed for a better passband characteristic. A notched characteristic is introduced by using modified feed lines to avoid the interferences with other existing signals. UWB bandpass filter performances in time-domain and frequency-domain are analyzed and discussed. Thirdly, UWB bandpass filters with a different configuration are developed. Similarly, the analyzed resonant frequencies are used to achieve a passband for UWB applications. A different technique is used to introduce a very narrow notched band within the passband. Time-domain analysis is made to verify the frequency-domain performance. Lastly, a very high selective wideband bandpass filter is presented using an inverted T-shaped resonator. The characteristic of the resonator is analyzed to design a bandpass filter with specified bandwidth. The short stubs are introduced to achieve a very high attenuation rate at both sides of the passband and a wide stopband characteristic. In summary, various microwave filters to meet the requirements of specific applications are studied and designed. Analysis and design methodology of the proposed microwave filters in this dissertation can be applied in many applications in wireless systems

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Impedance Transformers

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