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May 2008 Electrically Tune A Planar Inverted-F Antenna WITH THE PLETHORA of wireless standards being applied to today’s handheld devices, the antennas integrated in those products must often operate in 10 or more frequency bands. For the antenna designer, this translates into the challenge of having to cover a single very wide frequency band or multiple frequency bands while maintaining small size and high efficiency. A novel solution may be to use antennas that have a reconfigurable operating frequency with... — Nancy Friedrich May 2008 Dielectric Blood Measurement Detects HIV/AIDS DESPITE THE FACT THAT HIV/AIDS has grown into a worldwide pandemic, Elisa and Western Blot tests are still the only tests available for detecting it. Yet a new testing method could be based on the measurement of the dielectric properties of blood at microwave frequencies. Behind this proposed method are the efforts of C. Rajasekaran from the Department of Medicine at Medical College (Kerala, India) together with Anil Lonappan, Vinu Thomas, G. Bindu, Joe Jacob,... — Nancy Friedrich May 6, 2008 RFID Tags Take A Space Trip To Test Durability Laser coding and printing specialist DataLase along with US company Intermec and NASA have collaborated in the launch of a selection of marked RFID tags and aluminium discs into space... — Paul Whytock May 6, 2008 Wireless Brain Monitoring System Is Powered By Patient’s Body Heat Independent research centre, IMEC, has developed a battery-free wireless 2-channel EEG (electroencephalography or brain wave monitoring system) powered by a hybrid power supply using body heat and ambient light... — Paul Whytock April 2008 Constraints Impact UWB Antenna Performance Solutions for Optimal Waveforms for an Ultra-Wideband (UWB) link have been presented using transmit and receive antennas that are realistic and specific. Yet antenna expert David M. Pozar, who hails from the Department of Electrical and Computer Engineering at the University of Massachusetts (Amherst, MA), asserts that a better approach might be to determine the best performance that can be obtained for any antenna with certain constraints, such as... — Nancy Friedrich April 2008 UHF CPUs Promise To Secure RFID Communications To Attach to Merchandise Ranging from books to fresh foods, radio-frequency identification (RFID) tags need physical flexibility. RFID RF integrated circuits (RFICs) also must be produced at extremely low cost. In addition, they have to be able to provide secure communication. To meet these demands, a 13.56-MHz RF central-processing unit (CPU) with a flexible and a glass substrate was proposed by Hiroyuki Takashina and Yoshinari Yamashita from TDK... — Nancy Friedrich March Rectifier Circuit Powers Sensor Network Tags At 950 MHz In 1996, R.S. Dixon of Ohio state University proposed a new concept for a radio telescope array dubbed “Argus.” This approach used a large array of broadband antennas with broad beamwidth that provides all-sky field of view (FOV), can generate multiple simultaneous beams, and performs “retroactive observing.” The design of Argus, its theoretical performance, the system’s ability to detect and localize the sun, and various capabilities were recently... — Nancy Friedrich February 40-Gb/s Amplifiers Achieve 3-dB Bandwidth With High Gain MOST 40-Gb/s AMPLIFIERS suffer from limited gain, as the gain is often sacrificed for adequate bandwidth in high-speed operations. To conquer these design limitations, a circuit structure for broadband amplifiers has been proposed by Jun-Chau Chien and Liang-Hung Lu from the Department of Electrical Engineering and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei. In this new architecture, the gain cells in the conventional ... — Nancy Friedrich February Horn Antenna Aids Ground-Penetrating Radar TO SATISFY THE NEEDS FOR BOTH low and high frequencies in ground-penetrating radar (GPR), an Ultra Wideband (UWB) GPR that transmits a short-time pulse signal is often used. To ensure that its performance is sufficient, Ahmet Serdar Turk and Hakkl Nazli from the Scientific and Technical Research Council of Turkey (TUBITAK) have developed a hyper-wideband horn-array design. It is essentially an array combination of partial-dielectric transverse electromagnetic ... — Nancy Friedrich February DC-To-50-GHz LTCC Package Suits MM-Wave MMICs SURFACE-MOUNT monolithic-microwave-integrated- circuit (MMIC) packages must contain high-performance vertical transitions. Usually, such a transition will use viaholes, which act as an inductance and generates a discontinuity. In contrast, Inkwon Ju, In-Bok Yom, and Seung-Hyeub Oh from ETRI’s Satellite Communications RF Technology team have proposed a vertical transition that utilizes a trough line, slab line, and shielded multilayer coplanar waveguides (SMCPWs).... — Nancy Friedrich January 2008 Radio-Astronomy LNA Boasts Noise Figure Under 0.2 dB THE SQUARE KILOMETER ARRAY (SKA) radio synthesis telescope is estimated to require millions of receivers. To keep receiver cost down, CMOS technology is being looked at as an option. With recent improvements in CMOS transistors, this technology can even achieve the low noise figures needed in radio astronomy. At the University of Calgary’s (Calgary, Canada) Department of Electrical and Computer Engineering, Leonid Belostotski and James W. Haslett have achieved... — Nancy Friedrich January 2008 Imaging Systems Overcome Atmosphere And Materials BOTH HOMELAND SECURITY and military agencies have been seeking technologies that detect guns, knives and improvised explosive devices (IEDs). Using the millimeter and sub-millimeter wavebands, techniques to image people when they are close to a sensor have already been developed. Yet research by Roger Appleby from QinetiQ (Malvern, UK) and H. Bruce Wallace of MMW Concepts LLC (Havre De Grace, MD) examines standoff ranges above 5 m. In this range and in the open,... — Nancy Friedrich January 2008 Dielectric Waveguides Feed Millimeter-Wave Antennas FOR RECEIVER AND TRANSMITTER front ends in the millimeter-wave range to be widely used, certain problems must be resolved. An example is the connection of a miniature millimeterwave, monolithic integrated-circuit chip to an external antenna. To address this issue, Andreas Patrovsky and Ke Wu from the Poly-Grames Research Center at Ecole Polytechnique (Montreal, Quebec, Canada) developed a linear-array antenna fed by substrate integrated image guide (SIIG) at 94... — Nancy Friedrich December 2007 Luneberg Lens Offers Wide Scan With Multiple Pencil Beams Recently, there has been a resurgence in research interest in spherical Luneberg and homogeneous lens antennas for launching multiple pencil beams. With these approaches, all of the generated beams are almost identical because of the inherent symmetry of the structure. The result is very wide scan coverage of up to 180 deg. To specifically target millimeter-wave multi-fan-beam applications, a two dimensional (2D) Luneberg lens was recently proposed by Xidong Wu of... — Nancy Friedrich December 2007 BiCMOS VCO Competes For W-Band Applications Typically, millimeter-wave applications in the 75-to-100-GHz W-band requiring active devices have been considered the territory of III-V compound semiconductor technology. With fT/fMAX frequencies above 150 GHz, however, newer silicon- germanium (SiGe) processes can compete for those applications. W-band radar and radio transceivers require a phase-locked loop (PLL) in which the most critical components are the voltage- controlled oscillator (VCO) and frequency ... — Nancy Friedrich December 2007 Reflector System Could Satisfy Antennas On Spinning Platforms Current spacecraft antenna design must confront the problem of how to mount and deploy large reflector antennas on spinning platforms. The reflector spins at approximately 10 to 40 rpm to cover the desired scanned area on Earth. One solution - a back-to-back reflector antenna with a reduced moment of inertia - has been proposed by Keyvan Bahadori and Yahya Rahmat-Samii from the University of California, Los Angeles (UCLA).When both back-to-back reflectors are ... — Nancy Friedrich November 2007 SiGe Bipolar Broadband Amplifier Boasts 3-dB Bandwidth Above 84 GHz IN TODAY´S HIGH-SPEED communications systems, wideband amplifiers are created through a variety of techniques. Recently, engineers from Austria´s Technical University Vienna began working with designers from Infineon Technologies (Munich, Germany) on design considerations for inductorless broadband amplifiers based on the properties of the transistor in common collector configuration. This theory was then validated by a four-stage amplifier, which shows... — Nancy Friedrich November 2007 GaN HEMT Amplifier Delivers 80-Percent PAE At 2 GHz COMPARED TO THEIR gallium-arsenide (GaAs) counterparts, gallium-nitride transistors can offer significant performance improvements. GaN HEMT transistors in particular are suitable for Class F amplifiers, as they have a high fmax compared to the fundamental operating frequency. This aspect helps in the generation of higher-order harmonics needed for waveshaping. At the University of California, Santa Barbara, David Schmelzer and Stephen I. Long successfully... — Nancy Friedrich November 2007 Wireless Distribution System Eliminates Dispersion In Clock Networks AS SYSTEM OPERATING frequency and projected die size increase, it has become more difficult to distribute clock signals across a chip. The resulting problems include larger R-C delays, tighter skew and jitter tolerance, and signal dispersion along metal interconnect paths. To reduce skew and the impact of dispersion, a compact, wireless clock distribution system with an external planar antenna has been proposed by Maxim´s Ran Li, Silicon Laboratories´... — Nancy Friedrich October 2007 Negative-Resistance Cell Benefits Millimeter-Wave CMOS VCO Many advanced communication and sensor systems include millimeter-wave voltage-controlled oscillators (VCOs) as key components. Recently, such devices have been realized in CMOS technology. Compared to III-V compound devices or silicon-germanium (SiGe) HBT, CMOS devices boast lower unit current-gain frequency and maximum oscillation frequency. It is therefore essential to investigate the highfrequency behavior of a negative-resistance cell when designing... — Nancy Friedrich  prev. page
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