There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Preface to the Second Edition. Preface to the First Edition. 1 Introduction. 2 Network Analysis. 2.1 Network Variables. 2.2 Scattering Parameters. 2.3 Short-Circuit Admittance Parameters. 2.4 Open-Circuit Impedance Parameters. 2.5 ABCD Parameters. 2.6 Transmission-Line Networks. 2.7 Network Connections. 2.8 Network Parameter Conversions. 2.9 Symmetrical Network Analysis. 2.10 Multiport Networks. 2.11 Equivalent and Dual Network. 2.12 Multimode Networks. 3 Basic Concepts and Theories of Filters. 3.1 Transfer Functions. 3.2 Lowpass Prototype Filters and Elements. 3.3 Frequency and Element Transformations. 3.4 Immittance Inverters. 3.5 Richards' Transformation and Kuroda Identities. 3.6 Dissipation and Unloaded Quality Factor. 4 Transmission Lines and Components. 4.1 Microstrip Lines. 4.2 Coupled Lines. 4.3 Discontinuities and Components. 4.4 Other Types of Microstrip Lines. 4.5 Coplanar Waveguide (CPW). 4.6 Slotlines. 5 Lowpass and Bandpass Filters. 5.1 Lowpass Filters. 5.2 Bandpass Filters. 6 Highpass and Bandstop Filters. 6.1 Highpass Filters. 6.2 Bandstop Filters. 7 Coupled-Resonator Circuits. 7.1 General Coupling Matrix for Coupled-Resonator Filters. 7.2 General Theory of Couplings. 7.3 General Formulation for Extracting Coupling Coefficient k. 7.4 Formulation for Extracting External Quality Factor Qe. 7.5 Numerical Examples. 7.6 General Coupling Matrix Including Source and Load. 8 CAD for Low-Cost and High-Volume Production. 8.1 Computer-Aided Design (CAD) Tools. 8.2 Computer-Aided Analysis (CAA). 8.3 Filter Synthesis by Optimization. 8.4 CAD Examples. 9 Advanced RF/Microwave Filters. 9.1 Selective Filters with a Single Pair of Transmission Zeros. 9.2 Cascaded Quadruplet (CQ) Filters. 9.3 Trisection and Cascaded Trisection (CT) Filters. 9.4 Advanced Filters with Transmission-Line Inserted Inverters. 9.5 Linear-Phase Filters. 9.6 Extracted Pole Filters. 9.7 Canonical Filters. 9.8 Multiband Filters. 10 Compact Filters and Filter Miniaturization. 10.1 Miniature Open-Loop and Hairpin Resonator Filters. 10.2 Slow-Wave Resonator Filters. 10.3 Miniature Dual-Mode Resonator Filters. 10.4 Lumped-Element Filters. 10.5 Miniature Filters Using High Dielectric-Constant Substrates. 10.6 Multilayer Filters. 11 Superconducting Filters. 11.1 High-Temperature Superconducting (HTS) Materials. 11.2 HTS Filters for Mobile Communications. 11.3 HTS Filters for Satellite Communications. 11.4 HTS Filters for Radio Astronomy and Radar. 11.5 High-Power HTS Filters. 11.6 Cryogenic Package. 12 Ultra-Wideband (UWB) Filters. 12.1 UWB Filters with Short-Circuited Stubs. 12.2 UWB-Coupled Resonator Filters. 12.3 Quasilumped Element UWB Filters. 12.4 UWB Filters Using Cascaded Miniature High- And Lowpass Filters. 12.5 UWB Filters with Notch Band(s). 13 Tunable and Reconfigurable Filters. 13.1 Tunable Combline Filters. 13.2 Tunable Open-Loop Filters without Via-Hole Grounding. 13.3 Reconfigurable Dual-Mode Bandpass Filters. 13.4 Wideband Filters with Reconfigurable Bandwidth. 13.5 Reconfigurable UWB Filters. 13.6 RF MEMS Reconfigurable Filters. 13.7 Piezoelectric Transducer Tunable Filters. 13.8 Ferroelectric Tunable Filters. Appendix: Useful Constants and Data. A.1 Physical Constants. A.2 Conductivity of Metals at 25 C (298K). A.3 Electical Resistivity rho in 10-8 m of Metals. A.4 Properties of Dielectric Substrates. Index.

Microstrip filters for RF/microwave applications

In-band full-duplex (IBFD) operation has emerged as an attractive solution for increasing the throughput of wireless communication systems and networks. With IBFD, a wireless terminal is allowed to transmit and receive simultaneously in the same frequency band. This tutorial paper reviews the main concepts of IBFD wireless. One of the biggest practical impediments to IBFD operation is the presence of self-interference, i.e., the interference that the modem's transmitter causes to its own receiver. This tutorial surveys a wide range of IBFD self-interference mitigation techniques. Also discussed are numerous other research challenges and opportunities in the design and analysis of IBFD wireless systems.

/pdf/in-band-full-duplex-wireless-challenges-and-opportunities-djlyhtrciu.pdf

In-Band Full-Duplex Wireless: Challenges and Opportunities

The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

http://science.sciencemag.org/content/sci/311/5758/208.full.pdf

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

Fiber-based structures are highly desirable for wearable electronics that are expected to be light-weight, long-lasting, flexible, and conformable Many fibrous structures have been manufactured by well-established lost-effective textile processing technologies, normally at ambient conditions The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns However, imparting electronic functions to porous, highly deformable and three-dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation This article attempts to critically review the current state-of-arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber-based wearable electronic products In addition, this review elaborates the performance requirements of the fiber-based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber-based electronic devices Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

A systematic study of the high frequency electrical properties of electro-textiles is presented in this paper. First, conductive thread characterization is completed with a waveguide cavity method. The effect of conductive thread density and comparison of several different types of conductive threads are included. Second, comparisons of knitted patterns and weave patterns are made in terms of effective electrical conductivity through a microstrip resonator method. The effect of various weave patterns on conductive and dielectric loss is detailed. Finally, the relevance of the high frequency characterization of the electro-textile materials is shown through electro-textile patch antenna fabrication and measurements. The efficiency of the fully fabric patch antenna is as high as 78% due to the use of low loss electrotextiles characterized in this paper.

High Frequency Properties of Electro-Textiles for Wearable Antenna Applications

This paper presents a fully wireless cardiac pressure sensing system. Food and Drug Administration (FDA) approved medical stents are explored as radiating structures to support simultaneous transcutaneous wireless telemetry and powering. An application-specific integrated circuit (ASIC), designed and fabricated using the Texas Instruments 130-nm CMOS process, enables wireless telemetry, remote powering, voltage regulation, and processing of pressure measurements from a microelectromechanical systems (MEMS) capacitive sensor. This paper demonstrates fully wireless-pressure-sensing functionality with an external 35-dB·m RF powering source across a distance of 10 cm. Measurements in a regulated pressure chamber demonstrate the ability of the cardiac system to achieve pressure resolutions of 0.5 mmHg over a range of 0-50 mmHg using a channel data-rate of 42.2 kb/s.

Fully Wireless Implantable Cardiovascular Pressure Monitor Integrated with a Medical Stent

This paper presents the modeling, design, fabrication, and measurement of microelectromechanical systems-enabled continuously tunable evanescent-mode electromagnetic cavity resonators and filters with very high unloaded quality factors (Qu). Integrated electrostatically actuated thin diaphragms are used, for the first time, for tuning the frequency of the resonators/filters. An example tunable resonator with 2.6:1 (5.0-1.9 GHz) tuning ratio and Qu of 300-650 is presented. A continuously tunable two-pole filter from 3.04 to 4.71 GHz with 0.7% bandwidth and insertion loss of 3.55-2.38 dB is also shown as a technology demonstrator. Mechanical stability measurements show that the tunable resonators/filters exhibit very low frequency drift (less than 0.5% for 3 h) under constant bias voltage. This paper significantly expands upon previously reported tunable resonators.

High- $Q$ Tunable Microwave Cavity Resonators and Filters Using SOI-Based RF MEMS Tuners

In this paper, the authors present a design technique that enables inter-resonator and external coupling control for high-quality-factor (Q) tunable bandpass filters. The design incorporates low-Q varactors as part of the inter-resonator and external coupling mechanisms without degrading the overall high Q of the original filter. Detailed design methodology and equations are presented to illustrate the concepts. A first-time demonstration of these concepts is presented for a widely tunable high-Q evanescent-mode cavity bandpass filter. The cavities are integrated in a low-loss substrate with commercially available piezoelectric actuators and solid-state varactors for frequency and bandwidth tuning. This technique allows for reduced bandwidth variation over large tuning ranges. As one example, a constant 25-MHz absolute-bandwidth filter in the 0.8-1.43-GHz tuning range with loss that is as low as 1.6 dB is presented as an example. The filter third-order intercept point is between 32.8 and 35.9 dBm over this tuning range. To further show the impact of the technique on high- Q filters, a filter Q that is as high as 750 is demonstrated in the range of 3-5.6 GHz, while using low-Q varactors (Q < 30 at 5 GHz for a 0.4-pF capacitance) to achieve more than 50% reduction in bandwidth variation over the tuning range.

William J. Chappell

Papers

High Frequency Properties of Electro-Textiles for Wearable Antenna Applications

Fully Wireless Implantable Cardiovascular Pressure Monitor Integrated with a Medical Stent

High- $Q$ Tunable Microwave Cavity Resonators and Filters Using SOI-Based RF MEMS Tuners

High- $Q$ Fully Reconfigurable Tunable Bandpass Filters

Paper spray ionization devices for direct, biomedical analysis using mass spectrometry