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Microwave Theory and Techniques, IEEE Transactions on

Issue 10 • Date Oct. 2003

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Displaying Results 1 - 15 of 15
  • Comments on "Cross-coupling in coaxial cavity filters-a tutorial overview

    Publication Year: 2003 , Page(s): 2147
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  • Corrections to "Comparison of fully distributed and periodically loaded nonlinear transmission lines"

    Publication Year: 2003 , Page(s): 2147 - 2148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

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  • The transfinite-element time-domain method

    Publication Year: 2003 , Page(s): 2097 - 2105
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (506 KB) |  | HTML iconHTML  

    This paper presents an efficient time-domain method for computing the propagation of electromagnetic waves in microwave structures. The procedure uses high-order vector bases to achieve high-order accuracy in space, Newmark's method to provide unconditional stability in time, and the transfinite-element method to truncate the waveguide ports. The resulting system matrix is real, symmetric, positive-definite, and can be solved by using the highly efficient multilevel preconditioned conjugate gradient algorithm. Since the method allows large time steps and nonuniform grids, the computational complexity for problems with irregular geometries is superior to that of the finite-difference time-domain method. View full abstract»

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  • Feed horn coupled bolometer arrays for SPIRE - design, simulations, and measurements

    Publication Year: 2003 , Page(s): 2139 - 2146
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    In this paper, we present the design, modeling, and measurements of feed horn coupled large bolometer arrays being developed for the Herschel Space Observatory's Spectral and Photometric Imaging REceiver (SPIRE) instrument. SPIRE has five arrays of feed horn coupled silicon-nitride micromesh "spider-web" bolometers in two instruments, a three-band photometer, and a two-band Fourier transform spectrometer, each covering the 430-GHz-1.5-THz band. The optical coupling efficiency, bandwidth, and crosstalk between adjacent pixels of the arrays were investigated with numerical electromagnetic-field simulators, and prototype arrays were measured extensively in a test facility. The measured results were found to be in good agreement with simulation predictions, and the simulation results were used as a benchmark for the design goals of the instrument. View full abstract»

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  • A new method for pHEMT noise-parameter determination based on 50-Ω noise measurement system

    Publication Year: 2003 , Page(s): 2079 - 2089
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (701 KB) |  | HTML iconHTML  

    A new method for determining the four noise parameters of pseudomorphic high electron-mobility transistors (pHEMTs) based on a 50-Ω noise measurement system without a microwave tuner is presented. The noise parameters are determined based on the noise correlation matrix technique by fitting the measured noise figure of the active device. On-wafer experimental verification up to 26 GHz is presented and a comparison with a tuner-based method is given. The scaling rules for noise parameters have also been determined. Good agreement is obtained between simulated and measured results for 2×20 μm, 2×40 μm, and 2×60 μm gatewidth (number of gate fingers × unit gatewidth) 0.25-μm double-heterojunction δ-doped pHEMTs. View full abstract»

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  • Realization of transmission zeros in combline filters using an auxiliary inductively coupled ground plane

    Publication Year: 2003 , Page(s): 2112 - 2118
    Cited by:  Papers (38)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    The out-band transmission zeros of the multilayer low-temperature co-fired ceramic bandpass filter are studied. The design target of this filter, with passband between 2.3-2.65 GHz (the true application is 2.4-2.483 GHz), is to reject the local oscillator and image signals and, in the mean time, to suppress the harmonic frequency. This filter is a modified three-pole combline filter, which can easily achieve a high rejection rate and low insertion loss. The source-load coupling capacitor incorporation with cross-coupling grounding inductors can generate three transmission zeros. By properly adjusting the inductance values of the inductors between three resonators and ground the transmission zero can easily be manipulated at a high-side skirt to suppress the harmonic frequency. The measured results match well with the electromagnetic simulation that provides evidence for the feasibility of the proposed design. View full abstract»

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  • Evolutionary generation of 3-D line-segment circuits with a broadside-coupled multiconductor transmission-line model

    Publication Year: 2003 , Page(s): 2045 - 2054
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (716 KB) |  | HTML iconHTML  

    Evolutionary generation of three-dimensional microwave line-segment circuits embedded in a multilayer structure is presented. Connections of the line segments and their lengths are expressed by sets of parameters, which are evolutionarily optimized by the genetic algorithms. Practical optimization time is achieved by introducing models of broadside-coupled multiconductor transmission lines instead of full-wave electromagnetic (EM) calculations. The scattering parameters of the models are connected with the scattering parameters of vias, and are synthesized into that of the whole circuit. Using line segments, we can obtain not only small components for limited-space applications, but also large components for wide-band frequency specifications without increasing computational complexity. Two bandpass filters and a bandstop filter were designed and tested by an EM simulator. The bandpass filters were also fabricated and measured. The results validated our proposing procedure. View full abstract»

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  • Insertion loss of magnetostatic-surface wave transducers $transmission-line model and experiment

    Publication Year: 2003 , Page(s): 2126 - 2132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB) |  | HTML iconHTML  

    In this paper, a transmission-line model is developed for the computation of the insertion loss of magnetostatic-surface wave transducers and measurements are carried out by the authors to check this model. In a first step of the analysis, closed-form expressions for the solution of the telegrapher's equations for the two microstrip transducers are obtained. The insertion loss is then derived from this solution as a function of three transmission-line parameters, i.e., the propagation constant and the characteristic impedance of the YIG-loaded microstrip line and the mutual inductance between the two microstrips, these quantities being, in general, complex. In a second step, these transmission-line parameters are numerically computed by applying a full-wave method-of-moments technique. Thus, the theoretical results obtained are found to be in good agreement with experimental results. View full abstract»

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  • Electrical tuning of dispersion characteristics of surface electromagnetic-spin waves propagating in ferrite-ferroelectric layered structures

    Publication Year: 2003 , Page(s): 2090 - 2096
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    Electrical tuning of dispersion characteristics has been studied experimentally for hybrid surface electromagnetic-spin waves propagating perpendicularly to the direction of the static magnetization in tangentially magnetized layered structures containing ferrite and ferroelectric layers. The tuning is realized through the variation of the dielectric constant of the ferroelectric layer by changing the applied electric field. A comparison between experimentally measured and theoretically calculated dispersion characteristics is presented and shows a good agreement. View full abstract»

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  • Compact planar microstripline branch-line and rat-race couplers

    Publication Year: 2003 , Page(s): 2119 - 2125
    Cited by:  Papers (109)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    Both branch-line and rat-race couplers are easily realized using planar circuit technology as they employ only transmission lines without additional components. However, as the electrical lengths of the transmission line elements are either 90° or 270°, such couplers consume a significant amount of circuit area. This paper shows the development of branch-line and rat-race couplers that use artificial transmission lines (ATLs) in place of conventional transmission lines resulting in significant size reduction. As the ATLs are constructed entirely from microstriplines, the couplers are easily fabricated using conventional printed-circuit processes. The design formulas developed for the ATLs are explicit. Full-wave simulation and experimental results were used to confirm the design approach for hybrids operating at 1.8 GHz. The frequency response of the proposed hybrids is similar to conventional hybrids. View full abstract»

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  • Temperature compensation of total power radiometers

    Publication Year: 2003 , Page(s): 2073 - 2078
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    This paper describes a new technique to compensate output variations of total power radiometers due to physical temperature changes of the instrument. This technique performs the correction without the addition of expensive microwave hardware required in Dicke switching or many other widely used methods. A characterization period, over which the input antenna temperature is known, indicates the appropriate output adjustment needed for a change in physical temperature of the radiometer. The method effectively corrects the output in an example radiometer system built with inexpensive commercially available parts. For a 30-K variation in physical temperature, the measured data shows an improvement from 60-K peak-to-peak error to 6.9 K with an average absolute error of 1.1 K. View full abstract»

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  • Measurement/computation of effective permittivity of dilute solution in saponification reaction

    Publication Year: 2003 , Page(s): 2106 - 2111
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    For better application of microwaves in chemistry, the interaction between microwaves and the chemical reaction needs further study. Since the reactants form a complicated mixture, which changes with time, an effective permittivity can be used to describe the molecular polarization of the mixture in the reaction. The effective permittivity is expected to change with microwave frequency, temperature and reaction time. However, in many cases, the change of effective permittivity in a saponification reaction is too small to be detected using traditional methods. In this paper, we present a hybrid experimental/computational method for determining the effective permittivity in a saponification reaction. We use a resonant coaxial sensor to measure the reflection coefficients. To predict its performance, the electromagnetic-field distribution near the sensor and the reflection coefficient are calculated employing a frequency-dependent finite-difference time-domain method. Next, we develop a genetic-algorithm-based inverse-calculation technique and employ it to determine the complex permittivity of pure water from the measured reflection coefficient and compare the results with those obtained from Debye's equation. Finally, the hybrid experimental/computational method is employed to determine the effective permittivity of a dilute solution in a typical saponification reaction. Results are presented and discussed. View full abstract»

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  • Photodetectors based on heterostructures for opto-electronic applications

    Publication Year: 2003 , Page(s): 2063 - 2072
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1025 KB) |  | HTML iconHTML  

    In this paper, we present four photodetector devices that have the benefit of compatibility with established high electron-mobility transistor technology and are, thus, more conducive to monolithic integration with high-speed opto-electronic integrated circuitry. These AlGaAs-GaAs heterojunction-based planar devices all use the wide-gap material to enhance the Schottky barrier height between metal and semiconductor. We show that doping of this layer produces an internal electric field that aids in the transport and collection of photoelectrons. Addition of a resonant optical cavity by means of a distributed Bragg reflector reduces the required thickness of the absorption layer, thus achieving good responsivity and high speed, as well as wavelength selectivity. Current-voltage, current-temperature, photocurrent spectra, high-speed time response, and on-wafer frequency-domain measurements are presented, which point out that the often contradictory requirements of responsivity, noise, and speed may be addressed by proper engineering of the internal electric field and optical properties. Numerical simulations are performed to describe internal electric and optical behavior and a small-signal model based on frequency-domain data is extracted in order to facilitate photoreceiver design. The low dark current, in tens of femtoamps per square micrometer, full-width at half-maximum time responses below 10 ps, and high bandwidth in tens of gigahertz, make these devices of interest for applications ranging from optical communications to imaging systems. View full abstract»

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  • Guided-wave characteristics of periodic coplanar waveguides with inductive loading - unit-length transmission parameters

    Publication Year: 2003 , Page(s): 2133 - 2138
    Cited by:  Papers (45)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    Periodic coplanar waveguides (CPWs) with inductive loading are thoroughly studied by resorting to unit-length transmission parameters, i.e., propagation constant and characteristic impedance, of an equivalent dispersive and/or lossy transmission line. The admittance-type method of moments (MoM) is at first formulated to full-wave modeling of a finite-cell periodic CPW with the two feeding lines and then the short-open-calibration procedure is carried out to deembed the two-port ABCD matrix of the core periodic CPW section. Thus, the above two parameters can be extracted from the MoM simulation to exhibit their guided-wave characteristics, i.e., slow-wave and bandstop behaviors. It is demonstrated for the first time that, within the bandstop or bandgap, the propagation constant must become complex with a nonzero attenuation constant, while the characteristic impedance appears purely imaginary. Three periodic CPW circuits with six finite cells are then characterized on a basis of the transmission-line theorem and the derived S-parameters are validated by Momentum simulation and RF measurement. View full abstract»

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  • A time-domain approach to simulation and characterization of RF HBT two-tone intermodulation distortion

    Publication Year: 2003 , Page(s): 2055 - 2062
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (931 KB) |  | HTML iconHTML  

    In this paper, we evaluate the two-tone intermodulation distortion for heterojunction bipolar transistors (HBTs) operated at RF. We directly solve the nonlinear differential equations of the HBT large-signal model in time domain by employing the waveform-relaxation and monotone-iterative methods. Based on time-domain results, sinusoidal waveform outputs are transformed into the frequency domain with the fast Fourier transform. Furthermore, the output third-order intercept-point values of the HBT are computed with the spectra. Results for a fabricated InGaP HBT under different testing conditions are reported and compared among the HSPICE results, the results with harmonic balance methodology, and the measured data. Comparisons among these results show that our method demonstrates its superiority over the conventional approaches. This characterization alternative has allowed us to study RF device properties, perform thermal consumption and sensitivity analysis, and extract model parameters. View full abstract»

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Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

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