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Microwave Theory and Techniques, IEEE Transactions on

Issue 7 • Date July 2005

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Displaying Results 1 - 25 of 34
  • Table of contents

    Page(s): c1 - c4
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  • IEEE Transactions on Microwave Theory and Techniques publication information

    Page(s): c2
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  • An improved FDTD formulation for general linear lumped microwave circuits based on matrix theory

    Page(s): 2261 - 2266
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    An improved finite-difference time-domain (FDTD) formulation using the matrix theory is presented to analyze hybrid general linear lumped and distribution microwave circuits. Traditionally, since discrete current expressions of lumped circuits should be substituted into Maxwell's equations explicitly, the different discrete formulations of Maxwell's equations should be reconstructed when different active circuits are used. It will be much more difficult when high-order linear lumped circuits are considered in a hybrid system. In our improved formulation, a high-order linear lumped circuit is expressed by a serials of first-order modified integral transforms. When their interior variables together with electric fields, port voltage, and port current/current density of active circuits are considered as a vector, a local implicit and iterative matrix expression can be built. Compared with the traditional method, since our improved FDTD formulation is implicit, it easily combines with other active circuits built by the matrix method and decreases the condition number, is more stable, flexible, and general. Based on this formulation, the numerical stability and condition number are discussed. Simulation shows that the results by our improved FDTD formulation are in good agreement with that from commercial software. View full abstract»

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  • A new six-port junction based on substrate integrated waveguide technology

    Page(s): 2267 - 2273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB) |  | HTML iconHTML  

    A six-port junction based on the substrate integrated waveguide (SIW) technology is proposed and presented. In this design of such a junction, the SIW is first converted to an equivalent rectangular waveguide, then regular rectangular waveguide design techniques are used. In this structure, an SIW power divider and SIW hybrid 3-dB coupler are designed as fundamental building blocks. A six-port junction circuit operating at 24 GHz is fabricated and measured. Good agreement between simulated and measured results is found for the proposed six-port junction. View full abstract»

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  • Off-grid perfect boundary conditions for the FDTD method

    Page(s): 2274 - 2283
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB) |  | HTML iconHTML  

    We implement off-grid boundary conditions within Yee's finite-difference time-domain (FDTD) method without disturbing the existing uniform mesh or changing the standard FDTD code. Both perfect electric conductor and perfect magnetic conductor walls are considered. Examples of straight, slanted, and curved walls are shown, the latter two being represented by an enhanced staircase approximation. We show that: 1) offsets comparable to the spatial step size lead to instabilities and 2) this issue is easily resolved by stepping into the neighboring cell. The method enhances the flexibility of the FDTD method with respect to complex geometrical domains without reducing the spatial step. View full abstract»

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  • Microwave-tomographic imaging of the high dielectric-contrast objects using different image-reconstruction approaches

    Page(s): 2284 - 2294
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1096 KB) |  | HTML iconHTML  

    Microwave tomography is an imaging modality based on differentiation of dielectric properties of an object. The dielectric properties of biological tissues and its functional changes have high medical significance. Biomedical applications of microwave tomography are a very complicated and challenging problem, from both technical and image reconstruction point-of-views. The high contrast in tissue dielectric properties presenting significant advantage for diagnostic purposes possesses a very challenging problem from an image-reconstruction prospective. Different imaging approaches have been developed to attack the problem, such as two-dimensional (2-D) and three-dimensional (3-D), minimization, and iteration schemes. The goal of this research is to study imaging performance of the Newton and the multiplicative regularized contrast source inversion (MR-CSI) methods in 2-D geometry and gradient and MR-CSI methods in 3-D geometry using high-contrast, medium-size phantoms, and biological objects. Experiments were conducted on phantoms and excised segment of a pig hind-leg using a 3-D microwave-tomographic system operating at frequencies of 0.9 and 2.05 GHz. Both objects being of medium size (10-15 cm) possess high dielectric contrasts. Reconstructed images were obtained using all imaging approaches. Different approaches are evaluated and discussed based on its performance and quality of reconstructed images. View full abstract»

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  • An efficient method to reduce the numerical dispersion in the ADI-FDTD

    Page(s): 2295 - 2301
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    A new approach to reduce the numerical dispersion in the finite-difference time-domain (FDTD) method with alternating-direction implicit (ADI) is studied. By adding anisotropic parameters into the ADI-FDTD formulas, the error of the numerical phase velocity can be controlled, causing the numerical dispersion to decrease significantly. The numerical stability and dispersion relation are discussed in this paper. Numerical experiments are given to substantiate the proposed method. View full abstract»

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  • Design of microstrip quadruplet filters with source-load coupling

    Page(s): 2302 - 2308
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (872 KB) |  | HTML iconHTML  

    Quadruplet microstrip filters with source-load coupling are proposed to achieve similar skirt selectivity and/or in-band flat group delay as that of a sixth-order canonical form or an extracted pole microstrip filter. The diagnosis method of unwanted effects such as asynchronous resonant frequencies and unwanted couplings, which often occurs in the microstrip's open environment, is described in detail. A systematic design flow to implement a quadruplet microstrip source-load coupled filter with proper filter response is also provided. Two trial filters exhibited quasi-elliptical and flat group-delay response are designed and fabricated. Both theoretical and experimental results are presented. View full abstract»

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  • Verification of first circulation conditions of turnstile waveguide circulators using a finite-element solver

    Page(s): 2309 - 2316
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB) |  | HTML iconHTML  

    One means of adjusting the first circulation condition of any waveguide circulator is to have recourse to a finite-element (FE) solver. The purpose of this paper is to do so for each of the three possible geometries of the turnstile waveguide circulator. A complete statement of the first circulation condition also requires one of the susceptance slope parameter of the junction. This quantity is separately evaluated. The resonators under consideration are the side and apex coupled half-wave-long prism structures open circuited at each flat face and the conventional cylindrical geometry. The classic E-plane turnstile circulator using a prism resonator is also dealt with. The agreement between the existing literature and the FE adjustment is excellent. View full abstract»

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  • Time reversal with the FDTD method for microwave breast cancer detection

    Page(s): 2317 - 2323
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    The feasibility of microwave breast cancer detection with a time-reversal (TR) algorithm is examined. This algorithm is based on the finite-difference time-domain method, and compensates for the wave decay and, therefore, is suitable for lossy media. In this paper, we consider a two-dimensional breast model based on magnetic resonance imaging data, and examine the focusing abilities of a TR mirror comprised of an array of receivers with a single ultra-wideband pulse excitation. In order to resolve small 3-mm-diameter tumors, a very short duration pulse is necessary, and this requirement may restrict the applicability of the system due to hardware limitations. We propose a way to overcome this obstacle based on the observation that the amplitude and phase information of the tumor response is sufficient to achieve focusing. The robustness of the TR algorithm with respect to breast inhomogeneities is demonstrated, and the good performance of the method suggests it is a promising technique for microwave breast cancer detection. View full abstract»

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  • Novel compact parallel-coupled microstrip bandpass filters with lumped-element K-inverters

    Page(s): 2324 - 2328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    Novel compact parallel-coupled microstrip bandpass filters are proposed by using additional lumped inductors to realize K-inverters between coupled-line sections to achieve an equivalent to the quarter-wavelength (λ/4) resonator filters. As a result, the filter order can be doubled without increasing the circuit area, and no repeated passband is observed at twice the center frequency. In addition, by introducing the cross-coupling effect, two transmission zeros at upper and lower stopbands may be created. Simple equivalent-circuit models are also established as effective design tools. Specifically, several compact fourth-order microstrip bandpass filters with good stopband rejection are implemented and carefully examined. View full abstract»

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  • Compact EBG in-phase hybrid-ring equal power divider

    Page(s): 2329 - 2334
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    A novel electromagnetic-bandgap (EBG) in-phase hybrid-ring equal power divider is described. Coupled with the closed-form analytical expressions for the EBG structure, a systematic technique of design is presented for the first time. Compared to the conventional hybrid-ring equal power divider, based on the 15-dB return-loss criteria, an increase in both the input and output impedance bandwidth of approximately 10% from a starting frequency of 2.5 GHz, and a phase error of 0.006° within the passband have been achieved for the proposed structure. The proposed in-phase hybrid-ring equal power divider, besides providing a much broader bandwidth and occupying a smaller estate area, also possesses good harmonic suppression characteristic. View full abstract»

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  • Superconducting spiral wide bandpass filters with wide upper stopband

    Page(s): 2335 - 2339
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    Wide-band superconducting spiral bandpass filters have been successfully designed and tested. This extends the range of parameters that can be implemented using spirals. The shape of the spiral resonators was significantly modified to achieve the higher coupling coefficients required. A wide upper stopband was produced by using quarter-wave resonators for some of the spirals, and by shifting the second harmonic upwards for the others. One of the filters is eighth order with 1560-MHz center frequency and 27% bandwidth, and has an active area of only 9 mm×6 mm. View full abstract»

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  • Surface-passivated high-resistivity silicon as a true microwave substrate

    Page(s): 2340 - 2347
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (992 KB) |  | HTML iconHTML  

    This paper addresses the properties of a surface-passivated (enhanced) high-resistivity silicon (HRS) substrate for use in monolithic microwave technology. The detrimental effects of conductive surface channels and their variations across the wafer related to the local oxide and silicon/silicon-dioxide interface quality are eliminated through the formation of a thin amorphous layer at the wafer surface. Without passivation, it is found that the surface channels greatly degrade the quality of passive components in HRS by masking the excellent properties of the bulk HRS substrate and by causing a spread in parameters and peak values across the wafer. Moreover, it is seen that the surface passivation leads to excellent agreement of the characteristics of fabricated components and circuits with those predicted by electromagnetic (EM) simulation based on the bulk HRS properties. This is experimentally verified for lumped (inductors and transformers) and distributed (coplanar waveguide, Marchand balun) passive microwave components, as well as for a traveling-wave amplifier, through which also the integration of transistors on HRS and the overall parameter control at circuit level are demonstrated. The results in this paper indicate the economically important possibility to transfer microwave circuit designs based on EM simulations directly to the HRS fabrication process, thus avoiding costly redesigns. View full abstract»

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  • Wide-band superconducting coplanar delay lines

    Page(s): 2348 - 2354
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB) |  | HTML iconHTML  

    Two 25-ns high-temperature superconductor delay lines with novel double-spiral meander line structures were fabricated and measured, one based on the conventional coplanar waveguide (CPW) and the other based on the conductor-backed CPW. Compared with other published studies, the performance of the Conductor-backed CPW delay line is among the best in terms of the widest resonance-free band (2-18 GHz), low insertion loss (0.06 dB/ns at 60 K and 10 GHz), small ripple (<1 dB up until 16 GHz), and small dispersion (<2 ns in the variation of group delay between 2-18 GHz). This is also the first coplanar delay line successfully demonstrated without using wire bonding. The reflecting elements in the delay lines were identified through time-domain measurements. Full-wave simulations were performed to compare the double-spiral meander-line structure with conventional double-spiral line, and to identify the geometric factors restricting the bandwidth of the double-spiral meander line. View full abstract»

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  • On the RF/DSP design for efficiency of OFDM transmitters

    Page(s): 2355 - 2361
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    In this paper, a system-level RF/digital signal processing (DSP) design approach of power-efficient orthogonal frequency-division multiplexing (OFDM) transmitters is proposed. A DSP-based low-IF architecture, which allows a significant enhancement of their power and spectrum efficiencies, is proposed. The cascade of the peak-to-average power ratio (PAPR) reduction technique, predistortion technique, and the in-phase and quadrature modulation led to impressive improvement in the power efficiency and effective linear output power of the OFDM transmitter. Measurement results carried out on an IEEE 802.11a transmitter designed and built for this experiment are presented in terms of error vector magnitude (EVM), adjacent channel leakage ratio, and power efficiency. The power stage of this transmitter uses a heterojunction bipolar InGaP transistor operating in a deeply class AB. The cascade of the PAPR reduction and baseband predistortion processing modules results in the reduction of the power backoff operation point by approximately 10 dB accompanied by a relative increase in the wireless local area network transmitter power efficiency by roughly 400% while meeting the emission mask spectrum and EVM levels demanded by the 802.11a standard. View full abstract»

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  • Full-wave analysis of coupled lossy transmission lines using multiwavelet-based method of moments

    Page(s): 2362 - 2370
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    Full-wave analysis for coupled lossy transmission lines with finite thickness is conducted using a multiwavelet-based method of moments (MBMM). We use the multiscalets with multiplicity r=2 as the basis and testing functions, and take the discrete Sobolev-type inner products to discretize the integral equation and its derivative at the testing points. Since the numerical integration is not needed in the testing procedure, the new approach is faster, yet preserves high accuracy due to the derivative sampling. In the new approach, we compute the incoming fields in the spatial domain directly without resorting to the inverse Fourier transform. Hence, the local coordinate system used to perform the Sommerfeld integral is avoided and the computational cost is reduced remarkably. In addition, a coarser mesh can be used owing to the smoothness of the multiscalets. Numerical examples show that the MBMM speeds up the traditional method of moments 3 ∼ 10 times. View full abstract»

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  • Impedance matching considerations for ferrite Faraday rotators

    Page(s): 2371 - 2374
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    When a linearly polarized plane wave propagates from a dielectric medium into a medium with Faraday rotation, a reflected wave will always occur at the interface. This reflection is necessary because the normal-mode wave impedances in the medium with Faraday rotation are nondegenerate, while the equivalent normal-mode wave impedances for the dielectric medium are degenerate. Therefore it is not possible to match both normal modes simultaneously at the interface. This paper investigates the peculiar reflected wave associated with impedance matching of Faraday rotators, and shows that it should have minimal impact on practical devices. View full abstract»

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  • Experimental verification of nonuniform plasma layer model for quartz-silicon image guide phase shifters

    Page(s): 2375 - 2382
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    The optical control of millimeter waves in image guides composed of a quartz-silicon sandwich structure is investigated for use at W-band frequencies. The controllability of the dispersion characteristics is confirmed both theoretically and experimentally for single-moded guides using a pulse-modulated high-power semiconductor laser source. For the first time, measurement results of the frequency response of the phase shift are presented and, in addition to top side illumination, lateral illumination of the image guide is investigated. Differences between experimental and theoretical data based on a one-dimensional diffusion-controlled nonuniform plasma layer model are attributed to an inhomogeneity of the plasma distribution along the broadside of the silicon strip due to the impact of a huge surface recombination at the cutting area of the silicon strip. View full abstract»

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  • Bandpass filter of serial configuration with two finite transmission zeros using LTCC technology

    Page(s): 2383 - 2388
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    This study proposes a second-order bandpass filter of serial configuration. The filter schema incorporates a grounding capacitor, connecting the two conventional parallel LC resonators with the ground, to provide two finite transmission zeros. The impedance matrix and graphical solutions describe proposed filter's operation principle. To demonstrate the proposed filter schema, two bandpass filters, with center frequencies of 2.44 and 4.8 GHz, were designed and implemented using low-temperature co-fired ceramic multilayer technology. The measured results were found to agree well with the simulation results. The 2.44-GHz fabricated bandpass filter was found to possess low in-band insertion loss and high out-band suppression, making it suitable in wireless local area networks, Bluetooth, and RF home links. View full abstract»

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  • Analysis and design of wide-band SiGe HBT active mixers

    Page(s): 2389 - 2397
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    The frequency response of SiGe HBT active mixers based on the Gilbert cell topology is analyzed theoretically. The time-varying operation of the active mixer is taken into account by applying conversion matrix analysis. The main bandwidth-limiting mechanisms experienced in SiGe HBT active mixers performing frequency conversion of wide-band signals is discussed. The analysis is verified by computer simulations using a realistic high-frequency large-signal SiGe HBT model. An active mixer design based on the Gilbert cell topology modified for wide-band operation using emitter degenerated transconductance stage and shunt feedback load stage is discussed. Experimental results are given for an active mixer implemented in a 0.8-μm 35-GHz fT SiGe HBT BiCMOS process. View full abstract»

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  • On-wafer noise-parameter measurement using wide-band frequency-variation method

    Page(s): 2398 - 2402
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    In this paper, it is demonstrated that the newly proposed wide-band frequency-variation method, where only one set of matched and mismatched noise measurements is used, can efficiently determine the noise parameters of an ultra-sensitive transistor on-wafer at room temperature. Since the experimental setup is similar to that of conventional noise-temperature measurement while no complicated hardware is employed, this new approach is straightforward, yet efficient, and can be easily extended to applications with much higher or broader frequency ranges. Both the measured noise parameters of the post-amplifier stage and the transistor under test will be presented and investigated. View full abstract»

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  • Design and analysis of a 70-ps SiGe differential RF switch

    Page(s): 2403 - 2410
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    This paper presents the design and analysis of an SiGe high isolation single-pole double-throw (SPDT) differential absorptive switch at 24 GHz for pulsed ultra-wideband applications. Sub-100-ps envelope rise times are achieved through the use of differential current steering. The SPDT results in 1.9 dB of gain in the passband and an isolation of 35 dB while remaining matched at its ports (absorptive). The measured rise time of the RF envelope is 70 ps using a transistor with an fT of 80 GHz and agrees with both the simulated and analytically determined values. View full abstract»

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  • Design of generalized Chebyshev filters with asymmetrically located transmission zeros

    Page(s): 2411 - 2415
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    A simple design technique is introduced for generalized Chebyshev filters with asymmetrically located transmission zeros. The efficient and exact procedure is given for the calculation of transmission zeros for a class of generalized Chebyshev low-pass prototype filters with a maximum of four asymmetrically located transmission zeros of any multiplicity. This technique is based on obtaining the frequencies of magnitude characteristic extreme values in closed form, and after this, transmission zeros can be calculated by solving a system of nonlinear equations. Novel formulas for orders of zeros of maximally selective filters with equiripple characteristics in the passband and stopband are deduced. The obtained results are verified and illustrated by given examples. View full abstract»

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  • Parameter extraction for on-chip interconnects by double-image Green's function method combined with hierarchical algorithm

    Page(s): 2416 - 2423
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    A novel double-image Green's function approach combined with the hierarchical algorithm is proposed to compute the frequency-dependent capacitance and conductance for the on-chip transmission lines and interconnects embedded in multiple SiO2 layers of the general CMOS process. The effect of a protective layer and lossy silicon substrate layer of the CMOS process are considered in the four-layer structure deduced by the equivalent dielectric-constant approach whose adaptability is further proven in this paper. This double-image Green's function approach is fast convergent with the increasing order of reflections and transmissions, which is further accelerated by the hierarchical algorithm for computation of the Green's function rapidly. Moreover, the proposed method avoids the computation of bound charges on the dielectric interfaces. The frequency-dependent capacitance and conductance gained from the proposed method are shown to be in good agreement with the data obtained by other relevant methods. View full abstract»

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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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