Nonradiative wireless power transfer using magnetically coupled coils is studied in order to transfer a predetermined amount of power at the maximum efficiency. Accordingly, a conceptual wireless power transfer system and a tuning method are presented. Such a study is essential for effectively exploiting the inherent ability of a given pair of coupled coils. With the equations for inductance and resistance calculations, the system performance is evaluated and verified with well-known experimental results and circuit simulations.

A Study of Loosely Coupled Coils for Wireless Power Transfer

The evolution of microwave filters and multiplexers for space application is described. The many advances are described within the context of the design of the overall communication subsystem. Emphasis is placed on the multipaction and passive intermodulation (PIM) considerations in designing high-power multiplexers. The impact of microwave filter technology in the channel characterization of satellite systems is described. The future directions of research and development are briefly discussed. >

Innovations in microwave filters and multiplexing networks for communications satellite systems

This paper reports on a new concept of narrow bandpass filters leading to perfectly controlled electrical responses within both the required operating bandwidth and adjacent undesired bands. A specific topology is considered for such a "global synthesis": in comparison with conventional filter performances, it provides significant improvements in terms of rejection control. The attenuated frequencies are each located apart from the bandpass frequencies and controlled by means of n transmission zeros introduced through original dual-behavior resonators (DBRs). These resonators are based on the association of different parallel open-ended stubs and allow the designer to independently control the in-band and out-of-band responses of the filter. A global synthesis approach is also discussed on a simplified architecture based on stepped impedance stubs, and the experimental results shown clearly validate the proposed concept. This simplification reduces the number of degrees of freedom when designing a DBR, and consequently the two transmission zeros become dependent.

Narrow bandpass filters using dual-behavior resonators

A class of new planar dual-mode filters are proposed and developed for hybrid and monolithic microwave and millimeter-wave integrated-circuit design. The novelty of the proposed structure is to use a pair of unequal crossed slots that are formed on a square patch resonator such that its radiation loss and structure size can be significantly reduced simultaneously. The physical background of the crossed slots on the patch resonator is explained. Our simulation results show that the proposed filter presents a number of attractive features for practical applications. It is found that the resonant frequency of a filter is reduced, e.g., by 36%, while its unloaded Q/sub 0/ is improved from 180 to 310 as the crossed slot length increases. The coupling characteristics of two degenerate modes backed by a resonator are studied with respect to unequal length of the crossed slots. A dual-mode filter is designed and fabricated with 1.6% bandwidth operating at 1.6 GHz to showcase our proposal. Measured results validate the design predictions well.

New planar dual-mode filter using cross-slotted patch resonator for simultaneous size and loss reduction

A compact circularly polarized (CP) co-designed filtering antenna is reported. The device is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system. In the proposed design, the patch functions simultaneously as the radiator and the last stage resonator of the filter, resulting in a low-profile integrated radiating and filtering module with a small overall form factor of $\mathbf{0.53{\lambda _0} \times 0.53{\lambda _0} \times 0.07{\lambda _0}}$ . It is shown that the filtering circuit not only ensures frequency selectivity but also provides impedance matching functionality, which serves to broaden both the impedance and axial ratio bandwidths. The designed filtering antenna was fabricated and measured, experimentally achieving an $\mathbf{{S_{11}} , an axial ratio of less than 3 dB and a gain higher than 5.2 dBi over a bandwidth from 3.77 to 4.26 GHz, i.e., around 12.2%, which makes it an excellent candidate for integration into a variety of wireless systems. A linearly polarized version of the integrated filtering antenna was also demonstrated. In addition, further full-wave simulations and experiments were carried out to verify that the designed CP filtering antenna maintains its properties even when mounted on different positions of the human body with various body gestures. The stable impedance and radiation properties also make it a suitable candidate as a wearable antenna for off-body wireless communications.

A Compact, Wideband Circularly Polarized Co-designed Filtering Antenna and Its Application for Wearable Devices With Low SAR

Foreword Preface Acknowledgments 1 Radio Frequency (RF) Filter Networks for Wireless Communications-The System Perspective PART I: INTRODUCTION TO A COMMUNICATION SYSTEM, RADIO SPECTRUM, AND INFORMATION PART II: NOISE IN A COMMUNICATION CHANNEL PART III: IMPACT OF SYSTEM DESIGN ON THE REQUIRMENTS OF FILTER NETWORKS 2 Fundamentals of Circuit Theory Approximation 3 Characterization of Lossless Lowpass Prototype filter functions 4 Computer-Aided Synthesis of Characteristic Polynomials 5 Analysis of Multiport Microwave Networks 6 Synthesis of a General Class of the Chebyshev Filter Function 7 Synthesis of Network - Circuit Approach 8 Coupling Matrix Synthesis of Filter Networks 9 Reconfiguration of the Folded Coupling Matrix 10 Synthesis and Application of Extracted Pole and Trisection Elements 11 Microwave Resonators 12 Waveguide and Coaxial Lowpass Filters 13 Waveguide Realization of Single- and Dual-Mode Resonator Filters 14 Design and Physical Realization of Coupled Resonator Filters 15 Advanced EM-Based Design Techniques for Microwave Filters 16 Dielectric Resonator Filters 17 AllPass Phase and Group Delay Equalizer Networks 18 Multiplexer Theory and Design 19 Computer-Aided Diagnosis and Tuning of Microwave Filters 20 High-Power Considerations in Microwave Filter Networks Appendix A Appendix B Appendix C Appendix D Index

Microwave Filters for Communication Systems: Fundamentals, Design and Applications

This paper describes the evolution and development of low power superconductive filters and multiplexers for satellite applications under the HTSSE-II program. Experimental results and tradeoffs are presented for thin film and dielectric loaded HTS multiplexer configurations, leading to the development and implementation of a fully integrated four-channel C-band HTS input multiplexer. Measured data shows performance comparable to conventional technology and promise of large reduction in mass and volume of such equipment. The multiplexer is scheduled to fly as part of the HTSSE-II package on the ARGOS satellite in 1996.

Design considerations of superconductive input multiplexers for satellite applications

The objective of this paper is to address the issues related to the commercial viability of employing high-power high-temperature superconductor (HTS) filters and multiplexers for communication satellites. Experimental results are presented for fully integrated contiguous HTS manifold-coupled output multiplexers. Both hybrid dielectric-resonator HTS filters as well as planar HTS filters are used to construct these multiplexers. The paper provides a detailed analysis of the cooling load of HTS high-power multiplexers, and describes how it varies with the achievable filter Q and the type of I/O RF cables. It also demonstrates the role that the I/O RF cables play in determining the cooling load of HTS subsystems.

Feasibility and commercial viability issues for high-power output multiplexers for space applications

This paper presents the measured results of a C-band 60-channel superconductive input multiplexer integrated with pulse-tube space-qualified cryocoolers. The multiplexer is developed to duplicate the requirements of the INTELSAT 8 program. The channel filters are self-equalized ten-pole high-temperature superconductor (HTS) planar structures designed with drop-in cryogenic ferrite circulators and isolators. This paper presents details on RF design, packaging, and cryocooler integration, as well as an assessment of overall reliability of using HTS equipment in a space environment. This paper demonstrates that at least 50% reduction in mass and 65% reduction in size can be achieved by replacing the INTELSAT 8 C-band dielectric-resonator input multiplexer with a superconductive multiplexer.

A 60-channel superconductive input multiplexer integrated with pulse-tube cryocoolers

The paper demonstrates the feasibility of building a fully integrated C-band 4-channel superconductive multiplexer employing 8-pole hybrid dielectric/HTS thin film filters. Experimental results are presented for 4-pole and 8-pole externally-equalized superconductive filters having 1% bandwidth. The measured data for the integrated multiplexer clearly indicates that C-band superconductive multiplexers are approaching the performance requirements of typical satellite systems and have the potential of large reduction in mass and volume over conventional technologies. The critical design considerations of such type of superconductive multiplexers are discussed. >

Chandra M. Kudsia

Papers

Microwave Filters for Communication Systems: Fundamentals, Design and Applications

Design considerations of superconductive input multiplexers for satellite applications

Feasibility and commercial viability issues for high-power output multiplexers for space applications

A 60-channel superconductive input multiplexer integrated with pulse-tube cryocoolers

A C-band superconductive input multiplexer for communication satellites