The Beauty of Symmetry: Common-mode rejection filters for high-speed interconnects and balanced microwave circuits

Common-mode rejection filters operating at microwave frequencies have been the subject of intensive research activity in the last decade. These filters are of interest for the suppression of common-mode noise in high-speed digital circuits, where differential signals are widely employed due to the high immunity to noise, electromagnetic interference (EMI) and crosstalk of differential-mode interconnects. These filters can also be used to improve common-mode rejection in microwave filters and circuits dealing with differential signals. Ideally, common-mode stopband filters should be transparent for the differential mode from DC up to very high frequencies (all-pass), should preserve the signal integrity for such mode, and should exhibit the widest and deepest possible rejection band for the common mode in the region of interest. Moreover, these characteristics should be achieved by means of structures with the smallest possible size. In this article, several techniques for the implementation of common-mode suppression filters in planar technology are reviewed. In all the cases, the strategy to simultaneously achieve common-mode suppression and all-pass behavior for the differential mode is based on selective mode-suppression. This selective mode suppression (either the common or the differential mode) in balanced lines is typically (although not exclusively) achieved by symmetrically loading the lines with symmetric resonant elements, opaque for the common-mode and transparent for the differential mode (common-mode suppression), or vice versa (differential-mode suppression).MINECO, Spain-TEC2013-40600-R, TEC2013-41913-PGeneralitat de Catalunya-2014SGR-15

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

Wideband phased array antennas and compact, harmonic-suppressed microstrip filters

Modern satellite, wireless communications, and radar systems often demand wideband performance for multi-channel and multi-function operations. Among these applications, phased array antennas play an important role. This dissertation covers two wideband phased array antennas, one produces linear polarization and one produces circular polarization. The main difference between these two phased array antennas is the antenna array. For the linearly polarized array, a wideband microstrip line to slotline transition is used to feed a Vivaldi antenna. For the circularly polarized array, a wideband microstrip line to parallel stripline transition is used to feed a spiral antenna. From 3 to 12 GHz, the linearly polarized beam is steered over ± 15º. Since the electromagnetic spectrum is limited and has to be shared, interference is getting serious as more and more wireless applications emerge. Filters are key components to prevent harmonic interference. The harmonic signals can be suppressed by cascading additional lowpass filters or bandstop filters. A bandstop filter combining shunt open stubs and a spurline is proposed for a compact size and a deeper rejection. Two lowpass filters with interdigital capacitors and slotted ground structures are also studied. Harmonic suppression can also be achieved with the modification of bandpass filters. Three conventional bandpass filters with spurious passbands are investigated. The first one is a dual-mode patch bandpass filter. The second passband of the proposed filter is at 2.88fo, where fo is the fundametal frequency. The second filter is an open-loop bandpass filter. Two open stubs are added to achieve high suppression in the second harmonic signal. The suppression of 35 dB at the second harmonic is obtained. For the third filter using half-wavelength open stubs, a T-shaped line is used to replace the quarter-wavelength connecting line. The T-shaped line has the same response with the connecting line in the passband. Furthermore, the T-shaped line works as a bandstop filter at the second harmonic. Finally, a new compact slow-wave resonator and bandpass filters are presented. A simple transmission-line model is used to predict the resonant frequency. Compared with the conventional uniform half-wavelength resonator, the slow-wave resonator shows a 25% size reduction

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

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

Size Reduction and Gain Enhancement of a Microstrip Antenna using Partially Defected Ground Structure and Circular/Cross Slots

Microwave engineers have been known to designedly created defects in the shape of carved out patterns on the ground plane of microstrip circuits and transmission lines for a long time, although their implementations to the antennas are comparatively new. The term Defected Ground Structure (DGS), precisely means a single or finite number of defects. At the beginning, DGS was employed underneath printed feed lines to suppress higher harmonics. Then DGS was directly integrated with antennas to improve the radiation characteristics, gain and to suppress mutual coupling between adjacent elements. Since then, the DGS techniques have been explored extensively and have led to many possible applications in the communication industry. The objective of this paper is to design and investigate microstrip patch antenna that operates at 2.4 GHz for Wireless Local Area Network WLAN IEEE 802.11b/g/n, ,Zigbee, Wireless HART, Bluetooth and several proprietary technologies that operate in the 2.4 GHz band. The design of the proposed antenna involves using partially Defected Ground Structure and circular/cross slots and compare it to the traditional microstrip patch antenna.  The results show improvement in both the gain of 3.45 dB and the S11 response of -22.3 dB along with reduction in the overall dimensions of the antenna. As a conclusion, the performance of the antenna has been improved through the incorporation with the DGS and slots structures regarding the S11 response and the gain. The proposed antenna become more compact. Finally, the radiation pattern of proposed antenna has remained directional in spite of adding slots on the ground plane

The beauty of symmetry : common-mode rejection filters for high-speed interconnects and band microwave circuits

Common-mode rejection filters operating at microwave frequencies have been the subject of intensive research activity over the last decade. These filters are of interest for the suppression of common-mode noise in high-speed digital circuits, where differential signals are widely employed due to the high immunity to noise, electromagnetic (EM) interference, and crosstalk of differential-mode interconnects. These filters can also be used to improve common-mode rejection in microwave filters and circuits dealing with differential signals. Ideally, common-mode stopband filters should be transparent for the differential mode from dc up to very high frequencies (all pass), preserve the signal integrity for such mode, and exhibit the widest and deepest possible rejection band for the common mode in the region of interest. Moreover, these characteristics should be achieved by means of structures with the smallest possible size

Slotted Ground Structures and Their Applications to Various Microwave Components

This thesis discusses microstrip circuits and components with a slotted area on the ground plane. In recent years, various slot geometries have been placed on the ground plane with the purpose of reducing harmonics, producing frequency pass/stop-bands, and enhancing coupling effects. Among several ground slot geometries, a dumbbell shaped slot (DSS) is attractive because of its simple structure and easy analysis. The DSS and its applications to RF/microwave filters are studied and discussed. A lumped equivalent circuit model of the dumbbell shaped ground slot is introduced by utilizing resonator and filter theories. The accuracy of the equivalent circuit model is demonstrated through the comparison of circuit simulations and measurements. A lowpass filter (LPF) using slotted ground structure (SGS) with dumbbell shape is designed and measured to validate its theories. By using SGS techniques presented in this thesis, some other RF/microwave components such as a periodic structure, ultra-wideband bandpass filter (UWB-BPF), and rectenna with SGS-LPF are designed and tested