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Compact Size (compact + size)
Selected AbstractsElectrocaloric Materials for Solid-State RefrigerationADVANCED MATERIALS, Issue 19 2009Sheng-Guo Lu Abstract The electrocaloric effect (ECE) in dielectric materials has great potential in realizing solid-state cooling devices with compact size and high efficiency, which are highly desirable for a broad range of applications. This paper presents the general considerations for dielectric materials to achieve large ECE and reviews the experimental efforts investigating ECE in various polar dielectrics. For practical cooling devices, an ECE material must possess a large isothermal entropy change besides a large adiabatic temperature change. We show that polar dielectrics operated at temperatures near order,disorder transition have potential to achieve large ECE due to the possibility of large change in polarization induced by electric field and large entropy change associated with the polarization change. We further show that indeed the ferroelectric poly(vinylidene fluoride,trifluoroethylene)-based polymers display a large ECE, i.e., an isothermal entropy change of more than 55,J,(kgK),1 and an adiabatic temperature change of more than 12,°C, at temperatures above the order,disorder transition. [source] Compact UWB microstrip lowpass filter with novel CMRCINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2007Fei Zhang Abstract A novel beeline compact microstrip resonant cell, entitled BCMRC (beeline compact microstrip resonant cell), is firstly proposed and analyzed. The photonic bandgap and slow-wave effect of the BCMRC are evaluated. The compact configuration presents ultrawide stopband and improved slow-wave characteristics. Investigation of its scattering/radiation level is also included. An ultrawide band lowpass filter, consisting of three BCMRCs connected in series, is designed and fabricated. The filter has the advantages of low insertion loss in the passband, sharp, high and wide rejection in the stopband and compact size. The experimental results show good agreements with simulation results. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [source] Dendrimers and other dendritic macromolecules: From building blocks to functional assemblies in nanoscience and nanotechnologyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2003Jean M. J. Fréchet Abstract Given their size, in the single-digit nanometer range, and the versatility of their functionality, dendrimers and other dendritic macromolecules are poised to make a significant contribution to the rapidly expanding fields of nanoscience and nanotechnology. This highlight focuses on nascent applications of dendrimers that take advantage of their structural features and polyvalent character. In particular, the concept of dendritic encapsulation of function, borrowed from Nature, can be applied to the design of a varied array of energy-harvesting, light-emitting, or catalytic macromolecules. Similarly, the compact size and hierarchical ordering of components within dendrimers make them ideal for exploring the limits of nanolithography. Finally, the presence of differentiated functionalities and the polyvalent character of dendrons and dendrimers constitute strong assets for their use in polymer therapeutics. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3713,3725, 2003 [source] Compact top-loaded ultra-wideband biconical antenna for indoor base-station applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010W. J. Lu Abstract A biconical antenna employing the top-loaded technique is proposed for ultra-band (UWB) operation. The antenna is composed of a small cone mounted on a top-loaded disc and a conical ground plane, with both cones electrically connected together using four shorting pins to reduce the lower cutoff frequency. The antenna is investigated using computer simulation and measurement. Results show that the antenna has an impedance bandwidth from 0.8 GHz to over 11.2 GHz, dipole-like omnidirectional radiation pattern, average gain of about 4.2 dBi, and average radiation efficiency of over 88%. The antenna has the advantageous features of compact size, low profile, simple structure, and ultra-wideband characteristic and so is suitable for indoor base-station applications of many existing and future wireless and UWB systems. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2594,2598, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25540 [source] Broadband microwave gas sensor: A coaxial designMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010J. Rossignol Abstract The method of gas detection by a broadband microwave gas sensor is presented in this article. The principle of this method is to use a sensitive material as substrate of a transmission coaxial line. The sensor represents an open line with an extreme surface in contact with gas. The interaction with the gas and the surface induces a dielectric variation of the substrate. From experimental results, the interaction between the sensitive material and each tested gas present a specific frequency spectrum of the reflection coefficient at the input of the line. The proposed method has the advantage of a compact size, wide bandwidth, simple structure, and capable with all sensitive materials. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1739,1741, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25359 [source] Design of a planar ultra-wideband miniature monopole antenna for wireless USB dongle devicesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010Yu-Chia Chang Abstract This article proposes a 3.1,5 GHz ultra-wideband antenna, defined by a ,10 dB return loss. The simplified planar antenna structures, compact size, and low profile make it profitable to the application of the embedded antenna in wireless universal serial bus dongle devices. The slit shape on the monopole radiator is tuned for miniature antenna size. A parasitic stub on the ground is adopted to increase antenna bandwidth for achieving 3.1,5 GHz impedance bandwidth. To reduce manufacturing cost and practical fabrication, we also propose a simplified rectangular antenna structure. It is found that wideband characteristics of the simplified rectangular structure antenna are similar to that of semicircular base structure. Finally, the antenna prototypes are fabricated and the antenna characteristics are measured. The radiation patterns are omnidirectional in azimuth cut. Moreover, the S -parameter of antenna characteristics has been measured. The consistency between the simulated results and the measurement results confirms the practicability of these techniques. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1013,1016, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25121 [source] A highly integrated Ka-band transceiver module with two channelsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010Zhigang Wang Abstract A compact Ka-band square-wave modulation transceiver module with two receiving and transmitting channels is presented. This module consists of 15 monolithic microwave integrated circuits, two dielectric resonator oscillators, a E-plane waveguide filter, a coupler, two power dividers, and over 200 components, and works at two Ka-band operating frequency points. The developed Ka-band transceiver module is fabricated using advanced packages techniques, which has a compact size of 120 mm × 60 mm × 20 mm and exhibits greater than 500 mw output power with amplitude imbalance of two output ports less than 30 mw, switch rise time and fall time less than 4 ns, isolation of transmitting two channels more than 63 dB, and voltage standing wave ratio of receiving ports better than 1.3. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 615,618, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25005 [source] Microstrip ring resonator bandpass filters using ceramic substrateMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2010Yuan-Bin Chen Abstract The miniaturization of ring bandpass filters by employing high-permittivity ceramic substrates (with respective dielectric constants of 9.7 and 23.5) are investigated. Microwave dielectric ceramics with high permittivity are commonly applied in several microwave communication components. With the advantages of compact size, high-permittivity ceramics can be used as the substrate for bandpass filters. Moreover, the fundamental characteristics of newly developed compact square-ring resonators have also been described and applied to the design of bandpass filters. In this paper, the designed square-ring resonators structures are simulated using an IE3D simulator. The responses of the fabricated bandpass filters using Al2O3 (,r = 9.7, tan , = 0.000036) and 0.875Mg0.95Zn0.05TiO3 -0.125Ca0.8Sm0.4/3TiO3 (,r = 23.5, tan , = 0.000021) ceramic substrates are designed at the center frequency of 2.4 GHz. This compact size, low loss bandpass filter should be useful in many wireless communication systems. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 218,220, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24847 [source] Compact directional antenna for ultra wideband microwave imaging systemMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2009A. M. Abbosh Abstract A planar antenna of tapered slot configuration for use in ultra wideband microwave imaging systems aimed for early breast cancer detection is presented. It is designed to operate across the ultra wideband frequency (3.1,10.6 GHz) in a liquid of a high dielectric constant that matches the electric properties of average breast tissues. It has a very compact size with overall dimensions of 0.9 cm × 1 cm. The antenna's ultra wideband performance even when it is close to the breast tissues and its distortionless response in the time domain make it suitable for the microwave imaging systems utilizing a short-pulse radar technique. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2898,2901, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24764 [source] Compact ultra-wide band microwave filter utilizing quarter-wave length short-circuited stubs with reduced number of viasMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2009Mohammad Shahrazel Razalli Abstract We present here a novel pattern with compact size of ultra-wide band microstrip filter. The filter is originally modeled from five poles quarter-wavelength short-circuited stubs. It is then, transformed into a new compact butterfly-like pattern. This new "butterfly-shaped" pattern consists of three vias instead of five vias from its original design. The prototype has shown an improvement in scattering parameters measurement compared with its original model. It delivers 112% of fractional bandwidth, magnitude of insertion loss better than 1.6 dB and return loss lower than ,8 dB. It is fabricated on RT Duroid 5880 with 2.2 dielectric constant, 0.508 mm of substrate thickness and 35 ,m copper thickness. The overall dimension of the filter is 20.7 × 15.8 mm2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2116,2119, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24568 [source] A novel compact ultrawideband (UWB) bandpass filter using multiple-mode resonatorMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2009D. Chen Abstract In this letter, a novel compact ultrawideband (UWB) bandpasss filter (BPF) using the proposed multiple-mode resonator (MMR) is presented. The MMR is composed of a conventional microstrip hairpin resonator of which the two arms are connected by a section of microstrip line and a short-circuited point located in the middle of the hairpin resonator. Its first three resonant modes can be utilized to construct the UWB band. The tapped feeding structure has been used to realize desired tight couplings for designing the UWB BPF. The filter has been investigated numerically and experimentally. Both the simulated and measured results show that the filter has good performance, such as compact size, low-insertion loss, small group delay variation, and improved out-of-band performances. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1662,1664, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24424 [source] Compact low pass filter using novel elliptic shape DGSMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2009XiaoQun Chen Abstract A novel elliptic shape defected ground structure (DGS) is investigated for low pass filter (LPF) applications. An equivalent RLC circuit model is presented and its corresponding parameters are also extracted from the measured S-parameters. The filter presents the advantages of compact size, high selectivity, low insertion loss and high out-band suppression more than 32 dB from 5.15 to 10 GHz. Good agreements with response of equivalent circuit, electromagnetic simulation, and measurement is demonstrated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1088,1091, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24263 [source] Compact dual-band multilayer antenna element for nonlinear junction detector applicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009Krzysztof Wincza Abstract A compact dual-band antenna element for application in a nonlinear junction detector is proposed. To achieve broadband characteristics in two separate frequency ranges a stratified structure is proposed in which two driven and two parasitic patches are properly placed. For transmitting, a circularly polarized antenna is used in which stacked square ring resonators are applied to achieve simultaneously broadband operation and compact size. For receiving, a dual-polarized antenna is proposed in which a square patch is loaded by a square ring resonator to provide wide band and to allow for integration with the transmitting antenna. Theoretical calculations confirmed by measurement results are presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 696,699, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24136 [source] Low profile DOA finder at 2.4 GHzMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2009M. Uthansakul Abstract Technique to find direction of arrival (DOA) has been promisingly constructed by smart antenna technology. It consists of array antennas and signal processing unit. Because of the limitation of space in commercial products, the size of antenna array should be designed with the smallest dimension. Also the processing unit is expected in low complexity and expense. Most of DOA finders were recently proposed employing linear array in which the size is linearly increased as a number of antenna elements. Also the processing units were fully comprised with high level of computation. In this paper, the low profile of 2.4 GHz DOA finder is proposed. The DOA finder is designed in the compact size of 2 × 2 array antennas. Using modified Butler matrix, the processing unit is very simple in which it can be handled by any economic microprocessors. The proposed finder is able to delicately specify DOA in every angle from 0° to 360°. The experimental results confirm the success of proposed DOA finder. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 252,256, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23984 [source] A novel ultra-wideband monopole antenna with two symmetrical stripsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008Hyo W. Song Abstract In this article, we have described a novel ultra-wideband (UWB) monopole antenna with two symmetrical strips for wireless UWB communications. The proposed antenna consists of a center monopole, two symmetrical strips having one step on the strip, and CPW feeding. Three techniques (one monopole and two strips, symmetrical structure, and step on the strip) are used to produce the multiple resonance and low dispersion. The proposed UWB antenna has an omnidirectional radiation pattern, UWB, compact size, almost flat gain and linear phase, and low cost. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2845,2848, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23838 [source] Internal wideband monopole antenna for MIMO access-point applications in the WLAN/WIMAX bandsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2008Jui-Hung Chou Abstract A three-antenna MIMO system capable of generating a wide operating bandwidth of 2400,5850 MHz for access-point applications is introduced. The proposed design is based on a bent metal-plate monopole antenna with a compact size of 20 × 20 × 14 mm3. The three antennas are equally spaced along the perimeter of a circular ground and all generate a wide bandwidth of larger than 4 GHz. With the antenna short-circuiting facing the center of the ground, not only the overall antenna size is reduced but also good isolation of less than ,20 dB can easily be obtained. Calculated envelope correlation is also less than 0.002 across the operating band. The design prototype of the antenna is discussed in detail in the article. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1146,1148, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23333 [source] Compact design of T-type monopole antenna with asymmetrical ground plane for WLAN/WiMAX applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2008Wen-Shan Chen Abstract The article proposed and studied a compact coplanar waveguide-feed antenna for WiMAX applications. In this design, using notches on the ground plane and trapezoid-feed line is to generate broadband operation of 10-dB return loss from 1.95 to 6.55 GHz. Furthermore, embedded a narrow slit etching on the radiation patch accounts for triple-band operation of 1.68,2.71 GHz, 3.26,4.06 GHz, and 5.03,6.24 GHz. It plays a role as a filter to eliminate the undesired band. The proposed antenna with a band-reject characteristic is calibrated for WLAN/WiMAX applications which covers the band from 2.4 to 2.7, 3.3 to 3.8, and 5.15 to 5.85 GHz. And, this antenna has advantages of good radiation characteristics, compact size, and omni-directional patterns. Details of the proposed antenna configuration and experimental results are discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 515,519, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23120 [source] Ultra-wideband bandpass filter with a compact two-layered structureMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007Xinan Qu Abstract A novel ultra-wideband (UWB) bandpass filter with a compact size is proposed. By using a two-layered substrate configuration and an H-shaped slot on the ground, a vertical-coupled microstrip resonator structure is formed. Three resonant peaks of the proposed structure are extracted around the lower end, the center, and the upper end of the UWB passband. The compact two-layered filter has an overall length of about a half guided wavelength at the center UWB frequency and exhibits promising performance for UWB applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1049,1051, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22351 [source] A novel LTCC patch filter with sharp transition bandsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2007Jianhua Deng Abstract A novel compact low temperature co-fired ceramic (LTCC) patch filter is designed with sharp transition bands. The design is based on modified resonators, which can be used to provide transmission zeros located at arbitrary stopband frequency. Simple design procedure of the filter is also described. Good simulation and experimental results are obtained with insertion loss 1.2 dB and return loss of 15 dB at passband. This filter has a compact size of 2.5 mm × 4 mm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 989,991, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22313 [source] Internal GSM/DCS dual-band open-loop antenna for laptop applicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007Cheng-Hao Kuo Abstract A novel open-loop antenna with a coupled-line gap for application as an internal laptop antenna for GSM/DCS dual-band operation is presented. Owing to the use of the coupled-line gap, the proposed antenna can operate both as a half-wavelength loop structure at 900 MHz and a one-wavelength loop structure at 1800 MHz. The antenna is easily printed on a dielectric substrate with a low cost and is then integrated to the supporting metal frame of the laptop display to achieve a compact size of 9 mm in height and 70 mm in length, making it very promising to be embedded within the casing of the laptop as an internal antenna. Design considerations of the proposed antenna are described, and experimental and simulation results of the constructed prototype are presented. Effects of the coupled-line gap on the dual-band operation of the proposed antenna are also analyzed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 680,684, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22224 [source] High selective stepped-impedance dual-band bandpass filterMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2006Jianpeng Wang Abstract A high selective stepped-impedance dual-band bandpass filter is presented. The filter has a feature of two tunable passbands over a wide frequency range and compact size. A multi-coupling scheme is introduced so that two finite transmission zeros are generated between the two passbands to achieve a high out-of-band rejection. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1964,1966, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21831 [source] Compact CPW-fed dual folded-strip monopole antenna for 5.8-GHz RFID applicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2006Wen-Chung Liu Abstract A coplanar waveguide (CPW)-fed monopole antenna with dual folded strips for the radio frequency identification (RFID) application is presented. The proposed antenna has a very compact size, with, including ground plane, only 14 × 8 mm2, and can operate at the 5.8-GHz band with measured impedance bandwidth and average antenna gain of 450 MHz and ,5.5 dBi, respectively, and also monopolelike radiation patterns. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1614,1615, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21686 [source] A compact inverted double-L antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006Zhiming Zhuang Abstract A compact inverted double-L antenna (CDLA) fed by a microstrip line and operating at 2.45 GHz is presented in this paper. The linearly polarized CDLA can be constructed using conducting wires mounted on a small PCB board. This antenna maintains a simple structure, low profile, and compact size, which can be very useful for mobile communication systems such as Bluetooth and radio frequency identification (RFID) applications. Simulated and measured results are provided and good agreement between them is observed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 968,969, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21535 [source] High-dynamic-range C+L band variable optical attenuator using a titled angle shutterMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006Shien-Kuei Liaw Abstract A high-dynamic-range variable optical attenuator (VOA) using a movable shutter, which moves in a tilted-angle direction to the collimate fiber pair, is proposed. The VOA operates in the C+L band with the advantages low cost, high dynamic range of more than 50 dB, low insertion loss of 0.8 dB, low wavelength-dependent loss (WDL), and low polarization-dependent loss of ±0.4 dB and 0.4 dB, respectively, with attenuation of 50 dB. A compact size of 5.0 × 1.5 × 1.5 cm is obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1000,1002, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21547 [source] Printed band-notched ultra-wideband quasi-dipole antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2006Saou-Wen Su Abstract A printed ultra-wideband (UWB, 3.1,10.6 GHz) quasi-dipole antenna with the band-notched characteristic is presented. The antenna mainly comprises two radiating elements: an upper semi-circular disk and a lower semi-circular disk embedded with a pair of narrow slits, whose length is about one quarter-wavelength at the desired notched frequency. Both the upper and lower semi-circular disks are of the same dimensions, thus making the proposed antenna tend to be a dipole structure. With a compact size of 25 × 25 mm2, the proposed antenna showing UWB operation with a notched frequency band at 5 GHz is demonstrated. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 418,420, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21368 [source] Folded meandered-patch monopole antenna for low-profile GSM/DCS dual-band mobile phoneMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2002Fa-Shian Chang Abstract A novel low-profile monopole mobile phone antenna capable of GSM and DCS dual-band operations is proposed. The monopole antenna is easily constructed by folding a planar meandered patch into a rectangular-tube-like structure, and has a compact size of 9 × 9 × 34 mm3 for achieving 900- and 1800-MHz operations. Details of the proposed antenna design are described, and experimental results of a constructed prototype are presented and discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 84,86, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10380 [source] Compact dual-frequency PIFA with a chip-inductor-loaded rectangular spiral stripMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2002Shih-Huang Yeh Abstract By loading a chip inductor of suitable inductance (about 12 nH or less) to a planar inverted-F antenna (PIFA) with a shorted rectangular spiral strip, the frequency ratio of the antenna's first two resonant frequencies can be controlled, which makes dual-frequency operation with a desired frequency ratio easy to achieve. In addition, with the use of a shorted rectangular spiral strip, the proposed PIFA, has compact dimensions for a fixed dual-frequency operation. Design examples of the proposed PIFA with a compact size of 7.2 × 10 × 26 mm3 to achieve dual-frequency operation at about 900 and 1800 MHz are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 394,397, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10333 [source] The physical scale of the far-infrared emission in the most luminous submillimetre galaxies , II.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2010Evidence for merger-driven star formation ABSTRACT We present high-resolution 345-GHz interferometric observations of two extremely luminous (Lir, 1013 L,), submillimetre-selected galaxies (SMGs) in the Cosmic Evolution Survey (COSMOS) field with the Submillimeter Array (SMA). Both targets were previously detected as unresolved point sources by the SMA in its compact configuration, also at 345 GHz. These new data, which provide a factor of ,3 improvement in resolution, allow us to measure the physical scale of the far-infrared in the submillimetre directly. The visibility functions of both targets show significant evidence for structure on ,0.5,1-arcsec scales, which at z, 1.5 translates into a physical scale of ,5,8 kpc. Our results are consistent with the angular and physical scales of two comparably luminous objects with high-resolution SMA follow-up, as well as radio continuum and CO sizes of other SMGs. These relatively compact sizes (,5,10 kpc) argue strongly for merger-driven starbursts, rather than extended gas-rich discs, as the preferred channel for forming SMGs. [source] | |||||||||||||