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Microwave and Optoelectronics Conference (IMOC), 2009 SBMO/IEEE MTT-S International

Date 3-6 Nov. 2009

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Displaying Results 1 - 25 of 184
  • Brazilian contributions to the study of the ionosphere: Electron Content

    Publication Year: 2009 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9797 KB) |  | HTML iconHTML  

    Brazilian contributions to the study of the Electron Content are shown. These studies gave a major contribution for understanding the errors in the measurements made with the Global Navigation Satellite Systems (GNSS) receivers. Furthermore, a correlation study with the solar activity, and global maps illustrating the behavior of the Ionospheric Equatorial Anomaly are shown. View full abstract»

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  • Historical aspects on the development of Microwave Integrated Circuits in Brazil

    Publication Year: 2009 , Page(s): 6 - 10
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    This paper recalls some markers in the history of Microwave Integrated Circuits (MIC) in Brazil over the last 35 years, showing some typical examples of this development. View full abstract»

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  • The legacy of Prof. Gabriel Freire to contemporary research on microwave photonics at ITA

    Publication Year: 2009 , Page(s): 11 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9895 KB) |  | HTML iconHTML  

    This paper highlights some of what, from the author's perspective, were notable contributions of Prof. Gabriel Freire to the advancement of microwave photonics at ITA, Brazil. For nearly three decades, beginning in the early 1960s when he completed Master's and PhD programs in Electrical Engineering at Stanford University, he was a driving force in the development of ITA's graduate studies program. He was without a doubt a very good researcher, a learned scholar, and an inspiring teacher who kindled the spirit of discovery in his students. The paper intersperses his academic achievements with a few personal reminiscences provided by his former students and attempts to review his notable legacy to microwave photonics. View full abstract»

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  • A history of reflector antenna development: Past, present and future

    Publication Year: 2009 , Page(s): 17 - 23
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (21139 KB) |  | HTML iconHTML  

    The purpose of a reflector antenna is to confine most of the electromagnetic energy over a distributed aperture into a focal plane for communication or energy transfer; whereas, the purpose of this article is to focus a good portion of the history of reflector antenna development over a large time frame - including present and future - into a few pages. View full abstract»

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  • Radio science issues - contribution to disaster management

    Publication Year: 2009 , Page(s): 24 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1182 KB) |  | HTML iconHTML  

    Radio science activities covered by URSI (International Radio Science Union) are briefly reviewed. They encompasses the knowledge and study of all aspects of electromagnetic fields and waves in a wide frequency range running from micropulsation frequencies (i.e. from ~1 mHz) to Terahertz. The topics include: electromagnetic measurements and standards, electromagnetic theory and applications, radio-communication systems and signal processing, electronics and Photonics, electromagnetic environment and interference, wave propagation and remote sensing, ionospheric radio and propagation, waves in plasmas, radio astronomy, and electromagnetics in biology and medicine. A very preliminary analysis of potential radio science contribution to natural disaster management is presented. It is focussed on problems raised by radio communication and observation systems: before, during and after disasters. It points out the importance of a close collaboration between geoscience and engineering science: both to interpret observational data and to design new instruments. More elaborated analyses are needed to identify other challenges and collaborations. A call for collaborations between Scientific Unions as well as Research and Application organisms is launched. View full abstract»

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  • A 1.9-GHz CMOS Low Noise Amplifier with Partial Source Degeneration

    Publication Year: 2009 , Page(s): 30 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3450 KB) |  | HTML iconHTML  

    A 1.9 GHz fully integrated Low Noise Amplifier with Partial Source Degeneration technique (LNA-PSD) has been implemented in a 0.35 ¿m CMOS technology. This amplifier provides a forward gain of 11 dB with a noise figure of 3.4 dB while drawing 11 mW from a 1.8 V supply source. View full abstract»

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  • A high efficiency Si LDMOS Doherty power amplifier with optimized linearity

    Publication Year: 2009 , Page(s): 33 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7454 KB) |  | HTML iconHTML  

    This paper presents a high efficiency uneven UMTS Doherty power amplifier (DPA) based on Si LDMOS technology. An optimum output combining network was designed to enhance the efficiency at backoff power. High efficiency Si LDMOS transistors were used for the DPA design. The designed DPA has a maximum output power of Psat=39.7 dBm (9.4 W). A maximum drain efficiency of ¿max=54% (PAEmax=40%) was measured. The efficiency was maintained above ¿=40% (PAE =36%), over 6 dB backoff, and above ¿=32% (PAE=30%), over 9 dB backoff, relative to the maximum (saturated) output power. The designed PA was experimentally optimized to enhance its linearity. For a 1-carrier W-CDMA test signal, an ACPR of -44 dBc was measured at an average output power of Pout=30.7 dBm. View full abstract»

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  • Design techniques and considerations for mmwave SiGe power amplifiers

    Publication Year: 2009 , Page(s): 37 - 41
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (13422 KB) |  | HTML iconHTML  

    This paper describes the techniques to design a SiGe power amplifier (PA) for millimeter wave (mmW) applications. The design methodology of a balanced four-stage common emitter circuit topology was reported. The power amplifier was fully integrated including matching elements and bias circuit. The matching networks use coplanar waveguide (CPW) lines and MIM capacitors. Design considerations including parasitic elements, interconnections, pad model and matching structures are detailed. All these elements are taken into account to optimize the maximum output power. A comparison of the simulated and measured small-signal results is presented up to 110 GHz. The simulated and measured large-signal parameters are shown at 60, 65 and 77 GHz. View full abstract»

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  • Quaternary amplitude optical packets generated by four-wave mixing: Power level optimization

    Publication Year: 2009 , Page(s): 42 - 46
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1917 KB) |  | HTML iconHTML  

    A recent proposal suggests that four-wave mixing may be used to generate quaternary amplitude optical packets. We consider the reception of these packets and determine the optimal power level spacing that minimizes the bit error rate under the dominance of signal dependent noise. Results indicate a sensitivity of -23 dBm for a 12.5 GBaud optical packet. View full abstract»

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  • Protection schema for optical packet switching network with large number of nodes

    Publication Year: 2009 , Page(s): 47 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5913 KB) |  | HTML iconHTML  

    This work describes a new protection schema suitable for transparent optical networks with a large number of nodes. The protection and recovery processes are described as emerging functions in a bottom-up organized network obtained by connecting a large number of autonomous 2×2 optical packet switching nodes. The links are classified into sub-domains containing only four nodes each. During an emergency situation, only the small sub-domain that contains the failure must be reconfigured. Results show that the number of hops enhancement, due to failure, is smaller for larger number of nodes. View full abstract»

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  • Up-grading the physical topology of transparent optical networks using a multiobjective evolutionary algorithm considering quality of service and capital cost

    Publication Year: 2009 , Page(s): 51 - 56
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3137 KB) |  | HTML iconHTML  

    In this paper we propose a methodology based on an evolutionary multiobjective optimization algorithm for the problem of up-grading (expansion) the physical topology of transparent optical networks. The aim is to define the new topology layout and the specification of the new optical devices that should be deployed in an existing network in order to improve its performance, considering simultaneously the total installation cost (capital cost) and the total network blocking probability (performance criteria). To accomplish that, we propose a capital cost model for the network. We considered the following physical layer impairments: losses in optical devices, amplified spontaneous emission in optical amplifier and homodyne crosstalk in optical cross connect. The multiobjective optimization evolutionary algorithm used in the optimization process is the NSGA-II. Our proposed methodology can solve the expand physical topology design problem taking into account the physical layer impairments and the capital costs simultaneously. We also present a case study to show the effectiveness of our methodology. View full abstract»

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  • Cavity-backed cylindrical wraparound antennas

    Publication Year: 2009 , Page(s): 57 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3198 KB) |  | HTML iconHTML  

    This paper presents a method of moments analysis of cavity backed cylindrical wraparound antennas. It shows results for radiation pattern and input impedance, and compares them with those for similar geometries. The effects of the cavity are evaluated. View full abstract»

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  • Analysis of tapered micostrip patch antenna by the Wave Concept Iterative Procedure

    Publication Year: 2009 , Page(s): 61 - 66
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (14891 KB) |  | HTML iconHTML  

    This work presents the analysis of the tapered microstrip patch antenna by the Wave Concept Iterative Procedure, WCIP. The resonant frequencies variation with the patch dimensions and how to include it as project flexibility is discussed. The behavior of the electric fields is presented and analyzed for the first two resonant frequencies. Numerical and measured results are compared and a good agreement is observed. View full abstract»

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  • Current distribution of a printed dipole with arbitrary length embedded in layered uniaxial anisotropic dielectrics

    Publication Year: 2009 , Page(s): 72 - 77
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2589 KB) |  | HTML iconHTML  

    The current distribution of a printed dipole with arbitrary length embedded in several layers of anisotropic dielectrics is evaluated using the spectral domain immittance functions. In particular, the currents on a printed dipole on a single anisotropic layer and in three anisotropic layers are determined. A good comparison between the isotropic cases, commercial software and published literature is observed. Finally, general comments are made on how each component of the anisotropic permittivity affects the current distribution of the dipole. View full abstract»

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  • Ferrite substrate in patch antennas for millimeter wave applications

    Publication Year: 2009 , Page(s): 78 - 82
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2923 KB) |  | HTML iconHTML  

    This paper aims to study the radiation characteristics of annular ring microstrip antennas printed on a double-layered substrate that is constituted by an isotropic and a ferrite layers. The influence of the applied dc magnetic bias field on the radiation characteristics of these structures is examined. The analysis is performed in the Hankel transform domain using Hertz vector potentials and Galerkin method. Numerical results are presented for the antenna main characteristics such as resonant frequency and radiation pattern. View full abstract»

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  • Analysis of omnidirectional antennas with radome operating in LMDS band for signals of digital TV

    Publication Year: 2009 , Page(s): 83 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3073 KB) |  | HTML iconHTML  

    This work considers the use of dual-reflector antennas for omnidirectional coverage in a LMDS system base station to operate with the distribution of digital TV signals. We investigate the performance of omnidirectional antenna with and without dielectric radome. Numerical simulations based the method of moments are presented to illustrate the usefulness of the omnidirectional antennas to operate in LMDS systems. The analyses are conducted for a 20% bandwidth. It is used a radome with thickness equal to ¿/2 and relative permittivity equal to 2.08. The analyses intend to demonstrate the radome influence in the antenna behavior across the operation band and to identify the best radome thickness. View full abstract»

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  • Multilayer antenna with metamaterial using a full wave method

    Publication Year: 2009 , Page(s): 87 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5534 KB) |  | HTML iconHTML  

    This paper presents a study and development of equations consisting metamaterials of negative refraction index. The equations developed for this structure are based in full wave Transverse Transmission Line (TTL) method. This method allows obtaining concise equations. In order to analyze this structure the complex resonant frequency was determined. The results obtained for this application are presented. View full abstract»

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  • Skin effect considerations in K-Band designs

    Publication Year: 2009 , Page(s): 92 - 95
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5070 KB) |  | HTML iconHTML  

    In this paper, the skin effect of on-chip transmission lines and inductors at K-Band operating frequencies are investigated. Two microstrip lines with different lengths are simulated and compared with each other. A patterned ground shielded inductor is simulated using various meshing strategies and the results are compared. A 24 GHz common source CMOS low noise amplifier is designed, simulated and measured. The results show that, at K band operating frequencies Electro Magnetic simulations with proper edge mesh are able to model the skin effect precisely and show good agreement with the measured performance. View full abstract»

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  • Fabrication and testing of RF-MEMS switches using PCB techniques

    Publication Year: 2009 , Page(s): 96 - 100
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5415 KB) |  | HTML iconHTML  

    In this paper some design considerations and process development for fabricating RF MEMS switches on microwave laminate printed circuit boards (PCBs) are presented. PCB MEMS is a new technology, in which RF MEMS devices can be fabricated on any substrate, and can be monolithically integrated with other elements on the same substrate offering adaptability and reconfigurbility features to the communication systems. This work describes an alternative technique to improve manufacturing for fabrication of RF-MEMS switches on PCB. The integrated process uses metal as part of the sacrificial layer and the isotropic profile (undercut) of the wet etching to help on the bridge release. The mechanical characteristic and theory of operation of capacitive membrane switches is detailed. Pull-in voltage is in the range of 30-40 V. In the OFF state (up-position), the insertion loss is less than 0.3-0.4 dB up to 6 GHz. In the ON state (down-position), the isolation value is about 16 dB at 6 GHz and increases to 34 dB at 18 GHz. View full abstract»

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  • Conversion efficiency in axial monotrons

    Publication Year: 2009 , Page(s): 101 - 105
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5412 KB) |  | HTML iconHTML  

    A comparative study is given on the bunching mechanisms which develops in transit-time tubes with RF-field bunching, often referred to as monotrons. Uniform and stepped wise longitudinal electric-field profiles are discussed, and it is shown that the two-fold enhancement in the conversion efficiency of a monotron operating in the ¿ mode-instead of the longitudinally uniform TM010 mode for which the efficiency is limited to 20 percent-arises from a phase synchronization process due to the action of RF electric fields of reversed signs in each partition of the bisected cavity. View full abstract»

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  • 40 Gb/s RZ DQPSK transmission with SPM and ASE suppression by dispersion management

    Publication Year: 2009 , Page(s): 106 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3808 KB) |  | HTML iconHTML  

    We demonstrate a 40 Gb/s RZ DQPSK single channel transmission over 2900 km of SMF, using a 40 GHz bandwidth optical receiver filter to suppress ASE and improve OSNR. The interaction of SPM and accumulated dispersion is evaluated by minutely system dispersion management. Additionally, we successfully employ a 10 channel DWDM ranging from 1560.20 nm to 1563.86 nm at 40 Gb/s RZ DQPSK and 50 GHz of channel spacing over 1000 km, without raman amplification or special polarization multiplex. View full abstract»

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  • Dynamic PMD compensation at 43Gb/s for NRZ-ASK transmission

    Publication Year: 2009 , Page(s): 110 - 112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1556 KB) |  | HTML iconHTML  

    We report experimental PMD compensation in an ASK-NRZ transmission system at 43Gb/s. One- and two-section optical delay lines were evaluated. A large improvement in PMD robustness was achieved. View full abstract»

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  • Comparison of modulation formats for 40 Gb/s transmission in a 170 km link of the Kyatera Testbed

    Publication Year: 2009 , Page(s): 113 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5391 KB) |  | HTML iconHTML  

    This paper presents a theoretical comparison among six types of modulation formats applied to a 40 Gb/s transmission through the 170 km long Kyatera Testbed (Campinas - Sao Carlos, State of Sa¿o Paulo, Brazil). The formats are: NRZ-OOK, 33% RZ-OOK, 33% RZ-AMI, NRZDPSK, and 33% RZ-DPSK. The performance comparison, in terms of bit error ratio, is made for two system configurations: single-channel and 4-channel WDM in the ITU-T 100 GHz channel-spacing grid. For the single-channel results, NRZ-OOK is the only format which has not presented adequate BER, whilst all others resulted in a BER lower than 10-12, each one for a different range of transmitted power. For the WDM configuration, NRZ-OOK and CSRZ have not reached a satisfactory performance. The NRZ-DPSK has been the less impacted format in the WDM configuration in comparison to its results in the single-channel configuration. View full abstract»

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  • Multi-pump optimization for Raman+EDFA hybrid amplifiers under pump residual recycling

    Publication Year: 2009 , Page(s): 117 - 121
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4602 KB) |  | HTML iconHTML  

    A new technique to optimize the gain profile of broadband hybrid amplifiers is here proposed. It is based on the equalization of Erbium's gain spectrum by adjusting the flexible gain profile of a multi-pump Raman amplification stage. However, for increased power pump efficiency, the residual Raman pump is recycled by the Erbium-doped section. This hybrid amplifier is assessed in terms of single-channel global gain, ripple, and noise figure. Ripple values below 1 dB have been found in a bandwidth of approximately 30 nm under two and three pump configurations. View full abstract»

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  • Design of photonic devices using bio-inspired algorithms

    Publication Year: 2009 , Page(s): 122 - 126
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7022 KB) |  | HTML iconHTML  

    The design of photonic devices in computer simulators is a complex task and, in some cases, there are not analytical solutions to support. An alternative is the application of some optimizations techniques. For this reason, this work presents three different bio-inspired algorithms (GA, ES and AIS) to optimize three different photonic devices. The main objectives are providing a flexible and efficient computational optimization tool to design different photonic devices and benchmarking the efficiency of each one. In addition, the efficiency results compare the optimization convergence and computational efforts necessary for each optimization. View full abstract»

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