This tutorial presents an overview of the technological advances in millimeter-wave (mm-wave) circuit components, antennas, and propagation that will soon allow 60-GHz transceivers to provide multigigabit per second (multi-Gb/s) wireless communication data transfers in the consumer marketplace. Our goal is to help engineers understand the convergence of communications, circuits, and antennas, as the emerging world of subterahertz and terahertz wireless communications will require understanding at the intersections of these areas. This paper covers trends and recent accomplishments in a wide range of circuits and systems topics that must be understood to create massively broadband wireless communication systems of the future. In this paper, we present some evolving applications of massively broadband wireless communications, and use tables and graphs to show research progress from the literature on various radio system components, including on-chip and in-package antennas, radio-frequency (RF) power amplifiers (PAs), low-noise amplifiers (LNAs), voltage-controlled oscillators (VCOs), mixers, and analog-to-digital converters (ADCs). We focus primarily on silicon-based technologies, as these provide the best means of implementing very low-cost, highly integrated 60-GHz mm-wave circuits. In addition, the paper illuminates characterization techniques that are required to competently design and fabricate mm-wave devices in silicon, and illustrates effects of the 60-GHz RF propagation channel for both in-building and outdoor use. The paper concludes with an overview of the standardization and commercialization efforts for 60-GHz multi-Gb/s devices, and presents a novel way to compare the data rate versus power efficiency for future broadband devices.

http://faculty.poly.edu/~tsr/wp-content/uploads/publications/abstract17.pdf

State of the Art in 60-GHz Integrated Circuits and Systems for Wireless Communications

Ubiquitous blood pressure (BP) monitoring is needed to improve hypertension detection and control and is becoming feasible due to recent technological advances such as in wearable sensing. Pulse transit time (PTT) represents a well-known potential approach for ubiquitous BP monitoring. The goal of this review is to facilitate the achievement of reliable ubiquitous BP monitoring via PTT. We explain the conventional BP measurement methods and their limitations; present models to summarize the theory of the PTT-BP relationship; outline the approach while pinpointing the key challenges; overview the previous work toward putting the theory to practice; make suggestions for best practice and future research; and discuss realistic expectations for the approach.

/pdf/toward-ubiquitous-blood-pressure-monitoring-via-pulse-3274861uea.pdf

Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice.

This paper reviews recent advances in biomedical and healthcare applications of Doppler radar that remotely detects heartbeat and respiration of a human subject. In the last decade, new front-end architectures, baseband signal processing methods, and system-level integrations have been proposed by many researchers in this field to improve the detection accuracy and robustness. The advantages of noncontact detection have drawn interests in various applications, such as energy smart home, baby monitor, cardiopulmonary activity assessment, and tumor tracking. While many of the reported systems were bench-top prototypes for concept verification, several portable systems and integrated radar chips have been demonstrated. This paper reviews different architectures, baseband signal processing, and system implementations. Validations of this technology in a clinical environment will also be discussed.

A Review on Recent Advances in Doppler Radar Sensors for Noncontact Healthcare Monitoring

A method and system for providing electrical stimulation to tissue includes implanting one or more battery-free microtransponders having spiral antennas into tissue. Energy is provided wirelessly to the plurality of microtransponders. Tissue is stimulated using the energy.

Implantable Transponder Systems and Methods

The performance of the mobile phone handset antenna-chassis combination is analyzed based on an approximate decomposition of the waves on the structure into two resonant wavemodes: the antenna-element wavemode and the chassis wavemode. A double resonator equivalent circuit model is presented and used to estimate the impedance bandwidth and the respective distributions of radiation losses with typical parameter values at 900 and 1800 MHz. It is noticed that at 900 MHz, the radiation losses of the antenna element wavemode represent typically less than 10% of the total power. Thus, the antenna element works mainly as a matching element, which couples to the low-Q resonant wavemode of the chassis. At 1800 MHz, the contribution of the antenna element wavemode is larger. By enhancing the coupling and by tuning the chassis resonance, it is possible to obtain an impedance bandwidth of over 50% (6 dB return loss) at both at 900 and 1800 MHz. The results given by the equivalent circuit study are fully supported by those of three-dimensional phone-model simulations, including calculation of the SAR and efficiency values. In prototyping, the 6 dB bandwidth of 5.5% was obtained at 980 MHz with a nonradiating coupling element with a volume of 1.6 cm/sup 3/ on a 120 mm long chassis.

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Resonator-based analysis of the combination of mobile handset antenna and chassis

An X-band microwave life-detection system has been developed for detecting the heartbeat and breathing of human subjects lying on the ground at a distance of about 30 m or located behind a cinder block wall. The basic principle of the system is to illuminate the subject with a low-intensity microwave beam, and then from the back-scattered microwave signal, extract the heart and breathing signals that modulate it. The circuit description of the system and some experimental results are presented. Potential applications of the system are noted.

An X-Band Microwave Life-Detection System

A planar triangular monopole antenna (PTMA) is presented for high-frequency structure simulator ultra-wideband (UWB) communication. The high-frequency structure simulator three-dimensional electromagnetic solver is employed for design simulation. A printed PTMA has been realized by using the FR-4 printed circuit board substrate. The measured voltage standing wave ratio is less than 3 from 4 to 10 GHz. In the UWB communication frequency range, the measured phase distribution of the input impedance is quite linear and the H-plane patterns are almost omni-directional. The Kirchhoff's surface integral representation was adopted in the developed finite-difference time-domain code to compute the far field distributions from the near filed ones in time-domain. This is to investigate the radiated power density spectrum (PDS) shaping to comply with FCC emission limit mask. The effect of various source pulses (first-order Rayleigh pulses with /spl sigma/ of 20, 30, and 50 ps) on the radiated PDS shaping is also studied.

A planar triangular monopole antenna for UWB communication

Detailed numerical simulation, fabrication, and experimental measurements of a 2.4-GHz polarization-diversity printed dipole antenna are presented for wireless communication applications. Two orthogonal printed dipole antennas, each with a microstrip via-hole balun feeding structure, are combined and fabricated on an FR-4 printed-circuit-board substrate. A p-i-n diode circuit is used to switch and select the desired antenna polarization. In the antenna design simulation, a full-wave method of a three-dimensional finite-difference time-domain (FDTD) method is employed to analyze the entire structure of the printed antenna including the lumped elements of the polarization-selected p-i-n diode switching circuit. The Berenger perfectly matched layer absorbing-boundary condition is used for the FDTD computation. Numerical and measured results of antenna radiation characteristics, including input standing-wave ratio, radiation patterns, and polarization diversity are presented.

3-D FDTD design analysis of a 2.4-GHz polarization-diversity printed dipole antenna with integrated balun and polarization-switching circuit for WLAN and wireless communication applications

The design simulation, fabrication, and measurement of a 2.4-GHz horizontally polarized omnidirectional planar printed antenna for WLAN applications is presented. The antenna adopts the printed Alford-loop-type structure. The three-dimensional (3-D) EM simulator HFSS is used for design simulation. The designed antenna is fabricated on an FR-4 printed-circuit-board substrate. The measured input standing-wave-ratio (SWR) is less than three from 2.40 to 2.483 GHz. As desired, the horizontal-polarization H-plane pattern is quite omnidirectional and the E-plane pattern is also very close to that of an ideal dipole antenna. Also a comparison with the popular printed inverted-F antenna (PIFA) has been conducted, the measured H-plane pattern of the Alford-loop-structure antenna is better than that of the PIFA when the omnidirectional pattern is desired. Further more, the study of the antenna printed on a simulated PCMCIA card and that inserted inside a laptop PC are also conducted. The HFSS model of a laptop PC housing, consisting of the display, the screen, and the metallic box with the keyboard, is constructed. The effect of the laptop PC housing with different angle between the display and keyboard on the antenna is also investigated. It is found that there is about 15 dB attenuation of the gain pattern (horizontal-polarization field) in the opposite direction of the PCMCIA slot on the laptop PC. Hence, the effect of the large ground plane of the PCMCIA card and the attenuation effect of the laptop PC housing should be taken into consideration for the antenna design for WLAN applications. For the proposed antenna, in addition to be used alone for a horizontally polarized antenna, it can be also a part of a diversity antenna

A Horizontally Polarized Omnidirectional Printed Antenna for WLAN Applications

A novel technique to increase the bandwidth of the conventional planar triangular monopole antenna (PTMA) is presented. With two symmetrical corrugations extended from the flat ground plane, a significant improvement on the impedance bandwidth up to about 4:1 can be achieved. The proposed antenna design is a modification from the conventional volcano smoke antenna (VSA) and can be more compact and easily fabricated. The HFSS 3-D EM solver is employed for design simulation. The effects of the ridged ground plane on the impedance bandwidth are studied. A printed PTMA is fabricated on the FR-4 PCB substrate. Measured VSWR of the printed PTMA with the ridged ground plane is less than 2 from 3 to 12 GHz which covers the UWB frequency band. The measured antenna patterns also show the monopole-type omni-directional radiation patterns from 3 to about 10 GHz.

/pdf/a-3-12-ghz-uwb-planar-triangular-monopole-antenna-with-3ccuncnzjr.pdf

Huey-Ru Chuang

Papers

An X-Band Microwave Life-Detection System

A planar triangular monopole antenna for UWB communication

3-D FDTD design analysis of a 2.4-GHz polarization-diversity printed dipole antenna with integrated balun and polarization-switching circuit for WLAN and wireless communication applications

A Horizontally Polarized Omnidirectional Printed Antenna for WLAN Applications

A 3-12 GHz UWB Planar Triangular Monopole Antenna with Ridged Ground-Plane