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September 2008 [Components] Filter Covers 87.9 Percent Bandwidth Over 430 To 1105 MHz Mobile-coMMunications services require a filter’s tuning range to be extended by at least 2:1. Yet such a wide tuning range often yields increased insertion loss at the lowest resonant frequency. To compensate for this insertion loss, designers can leverage an active filter with negative resistance characteristics. Unfortunately, such a filter will require additional area and power consumption compared to passive designs. To solve this dilemma, a... — Jack Browne September 2008 [Computer-Aided Engineering] FETD Simulation Depicts In-Building Radar By simulating the radar pulses directed at buildings, engineers can better understand complex scattering mechanisms. They also can provide benchmark data for evaluating imaging algorithms. Previous work on wall-imaging algorithms has been rooted in techniques like synthetic-aperture-radar (SAR) imaging, time reversal, the boundary scattering transform, and beamforming with nonlinear inverse scattering algorithms. More recently, large-scale,... — Jack Browne September 2008 [Components] Filter Enables Control Of Resonant Frequency Mobile-communications systems have inspired the increasing development of high-dielectricconstant (K) microwave substrates. With a bandpass filter fabricated on a high-K piezoelectric substrate using an interdigital capacitor and bond-wire inductor, researchers hope to eliminate the inductive effect of wire bonds. The individuals behind this effort are: Min-Hang Weng from Taiwanâ??s National Nano Device Laboratories; Ru-Yuan Yang from National ... — Jack Browne August 2008 [Research & Development] X-Band Oscillator Antenna Targets Phased-Array Systems Active integrated antennas (AIAs) with one or more active devices and circuits within the radiating element have been garnering quite a bit of attention. They promise to deliver advantages like compact size, low cost, and adaptability to phased-array-antenna systems. Recently, an AIA element was successfully fabricated on a high-dielectric-constant ({? r} = 10.2) microwave laminate that is 0.635 mm thick. The development hails from Carl H. Mueller, Carol... — Nancy Friedrich August 2008 [Research & Development] 60-GHz Receiver May Be Realized In CMOS Wireless communications systems like highspeed personal-area networks and real-time video transmission demand performance that is above the Gigabit-per-second range. As a result, such systems may require the bandwidth provided by a 60-GHz millimeter-wave transceiver. The traditional approach behind such a transceiver is to leverage compoundsemiconductor monolithic microwave integrated circuits (MMICs). Yet, that 60-GHz transceiver may potentially be realized in... — Nancy Friedrich August 2008 [Research & Development] Three-Branch Antenna Serves GPS, UMTS, And ISM Bands Mobile-phone antennas must become increasingly multiband in order to accomplish their many functions. In response to these trends, researchers have proposed a design method that provides quarter-band operation for the following bands: GPS (1565 to 1585 GHz), UMTS/W-CDMA (1920 to 2170 MHz), Industrial Scientific Medical (ISM; 2400 to 2483.5 MHz), and SDMB (2630 to 2655 MHz). This work is credited to Byung-chan Jang, Che-young Kim, and Jeung-keun Park from the... — Nancy Friedrich July 2008 [Research & Development] Planar Folded Dipole Antenna Achieves Wideband Performance WIDEBAND WIRELESS SYSTEMS like Ultra Wideband (UWB) require antennas that are wideband and compact. One solution is a dipole antenna with folded elements, which is constructed by folding both ends of a folded dipole antenna to widen the antenna’s bandwidth. Research into a simplified configuration has been performed in Kanagawa, Japan by Shingo Tanaka, Satoru Horiuchi, Yasunori Atsumi, and Yoichi Ido from Yazaki Corp.’s Microwave Technology ... — Nancy Friedrich July 2008 [Research & Development] 24-Gb/s Software-Controlled Transmitter Outperforms Baseband Systems RECENTLY, A STUDY REVEALED a large gap between the fundamental limits of signaling (Shannon capacity) and the limits that are achievable with baseband signaling. In some applications, notches in the frequency domain are part of the link channels’ frequency response. Multitone (MT) signaling may then be employed to potentially reduce the gap between current link performance and Shannon capacity. Unfortunately, conventional MT techniques are not... — Nancy Friedrich July 2008 [Research & Development] On-Chip Slot Antennas Prove CMOS Approach ON-CHIP ANTENNAS can be used in applications from radio-frequency-identification (RFID) tags to RF sensors/radars. Gallium arsenide (GaAs) has been the most commonly used substrate in many of these applications. Yet active RF devices are expected to increasingly turn to silicon for its low cost, high integration and other advantages. Many researchers have sought to fabricate antennas on a silicon substrate. At China’s Shanghai Jiao Tong University,... — Nancy Friedrich June 2008 [Research & Development] Dielectric-Resonator Antenna Serves As Filter THE TREND TOWARD BUNDLING multiple components into a single module for wireless communications has researchers eying a dual-function DRA that can simultaneously act as the antenna and packaging cover. The problem is that the DRA’s quality (Q) factor tends to be low to enhance both radiation and bandwidth. In contrast, the Q-factor of the dielectric-resonator filter (DRF) is usually high to reduce insertion loss. It is therefore contradictory to... — Nancy Friedrich June 2008 [Research & Development] Microwave Approach Detects Lymphatic Disease LYMPHATIC FILARIASIS (LF) is a parasitic infection spread by mosquitoes. This disabling and disfiguring disease is caused by thread-like parasitic worms. To accomplish the earlier detection of LF, a microwave method has been presented by Anil Lonappan, Vinu Thomas, G. Bindu, Joe Jacob, and K.T. Mathew from the Department of Electronics, Microwave Tomography, and Materials Research Laboratory at India’s Cochin University of Science and Technology... — Nancy Friedrich June 2008 [Research & Development] Define Lightwave Antennas For Measurement Systems COMPARED TO MICROWAVE ANTENNAS, lightwave antennas have different measurement characteristics because of their use of shorter wavelengths. This aspect makes it difficult to design lightwave antennas according to each application system. A technique for measuring the far-field radiation pattern (FFP), gain, and transmissivity of each portion of an aperture has been described by Yasushi Munemasa, Tadashi Takano, and Makoto Mita from Tokyo University... — Nancy Friedrich May 2008 [Communications] 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 [Research & Development] 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 April 2008 [Communications] 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 [Communications] 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 [Components] Metamaterials Show Potential For Planar Components Metamaterials intrigue researchers for their potential to fabricate tunable and wideband passive components. Because of line parasitics, the reactive elements responsible for the left-handed (LH) band exhibit a forward or right-handed (RH) transmission band at higher frequencies. Usually, they are separated from the LH band by a stop band. Due to the composite behavior of LC loaded lines, these structures were called composite right/left-handed (CRLH) transmission lines.... — Nancy Friedrich March [Communications] 19.7-MHz Chebyshev LPF Targets IEEE 802.11n The IEEE 802.11n wireless-local-area-networking (WLAN) standard employs a high-throughput extension option. As a result, a WLAN system’s bandwidth can be 40 MHz in support of higher data rates. When the direct-conversion architecture is employed for these systems, a lowpass filter (LPF) with a bandwidth of 10 and/or 20 MHz is required. The design of a wideband LPF involves the selection of both the filter inductor-capacitorresistor (LCR) prototype (i.e.,... — Nancy Friedrich March [Research & Development] 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 [Research & Development] 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  prev. page
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