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Microwave Theory and Techniques, IEEE Transactions on

Issue 6 • Date Jun 1997

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Displaying Results 1 - 20 of 20
  • A high-accuracy realization of the Yee algorithm using non-standard finite differences

    Page(s): 991 - 996
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    New nonstandard second-order finite differences (FD's) are introduced, which when substituted into the Yee algorithm, reduce the solution error by a factor of 10-4 on a coarse computational grid. Using λ/h (grid spacings per wavelength)=8, one achieves the same accuracy as the standard Yee algorithm does at λ/h=1140. In addition, greater algorithmic stability allows a reduction in the number of iterations needed to solve a problem View full abstract»

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  • A high-performance W-band uniplanar subharmonic mixer

    Page(s): 955 - 962
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    A uniplanar subharmonic mixer has been implemented in coplanar waveguide (CPW) technology. The circuit is designed to operate at RF frequencies of 92-96 GHz, IF frequencies of 2-4 GHz, and LO frequencies of 45-46 GHz. Total circuit size excluding probe pads and transitions is less than 0.8 mm ×1.5 mm. The measured minimum single-sideband (SSB) conversion loss is 7.0 dB at an RF of 94 GHz, and represents state-of-the-art performance for a planar W-band subharmonic mixer. The mixer is broad-band with a SSB conversion loss of less than 10 dB over the 83-97-GHz measurement band. The measured LO-RF isolation is better than -40 dB for LO frequencies of 45-46 GHz. The double-sideband (DSB) noise temperature measured using the Y-factor method is 725 K at an LO frequency of 45.5 GHz and an IF frequency of 1.4 GHz. The measured data agrees well with the predicted performance using harmonic-balance analysis (HBA). Potential applications are millimeter-wave receivers for smart munition seekers and automotive-collision-avoidance radars View full abstract»

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  • Planar microwave integrated phase-shifter design with high purity ferroelectric material

    Page(s): 963 - 969
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    Ferroelectric materials (FEM's) are very attractive because their dielectric constant can be modulated under the effect of an externally applied electric field perpendicular to the direction of propagation of a microwave signal. FEM may be particularly useful for the development of a new family of planar phase shifters which operate up to X-band. The use of FEM in the microwave frequency range has been limited in the past due to the high losses of these materials; tan δ=0.3 at 3 GHz is typical for commercial BaTiO3 (BTO) and due to the high electric field necessary to bias the structure in order to obtain substantial dielectric constant change. In this paper, a significant reduction in material losses is demonstrated. This is achieved by using a new sol-gel technique to produce barium modified strontium titanium oxide [Ba1-xSrxTiO3 (BST)], which has ferroelectric properties at room temperature. Also demonstrated is how the use of thin ceramics reduces the required bias voltage below 250 V, with almost no power consumption required to induce a change in the dielectric constant. A phase shift of 165° was obtained at 2.4 GHz, with an insertion loss below 3 dB by using a bias voltage of 250 V. Due to the planar geometry and light weight of the device, it can be fully integrated in planar microwave structures View full abstract»

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  • Enhanced spatial network method for the analysis of open microstrip discontinuities

    Page(s): 905 - 910
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    In this paper, a new technique is presented for the numerical analysis of open boundary three-dimensional (3-D) vias embedded in multilayered strata. This approach is based on an enhanced spatial network method (SNM) algorithm, and leads to speed-up factors of 10-12 over the standard SNM implementation. Absorbing boundary conditions, based on the perfect matching layer (PML) concept, are implemented for open boundary truncation. Unlike the standard PML's, the proposed absorbing boundary conditions (ABC's) do not require introduction of additional variables View full abstract»

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  • Equivalent network representation of boundary conditions involving generalized trial quantities-application to lossy transmission lines with finite metallization thickness

    Page(s): 869 - 876
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    The derivation of integral equations for solving boundary conditions by mere application of analog Kirchhoff's and Ohm's laws is used. Generalized trial quantities are introduced as virtual adjustable sources in the equivalent network representation of boundary conditions. The lossy conductor domain of a planar transmission line is represented by a particular two-port. Thus, metallic losses can be evaluated for any metallization thickness without restricting the conductor modeling to a simple surface impedance approximation. In this paper, this two-port model is discussed and numerical results relative to a lossy coplanar waveguide (CPW) are presented. These results are in very good agreement with those obtained from the mode-matching technique and with other experimental data available in the literature. The size of matrices involved in the calculation of losses is twice as large as that in the lossless case. Moreover, the authors' formulation can be easily applied to superconducting planar transmission lines View full abstract»

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  • Characteristics of coplanar transmission lines on multilayer substrates: modeling and experiments

    Page(s): 939 - 945
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    Characteristics of coplanar transmission lines on multilayer substrates expressed in analytic formulas have been obtained using conformal mapping. The accuracy of these formulas has been verified experimentally on a variety of coplanar transmission lines using differential electro-optic (DEOS) sampling. For coplanar waveguides, the theory differs from the experiment by less than 3%; for coplanar striplines, the differences are less than 6% View full abstract»

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  • Inductance and quality-factor evaluation of planar lumped inductors in a multilayer configuration

    Page(s): 918 - 923
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    Integral representations for the self and mutual inductance of planar loops on a multilayered structure are derived. The integrals are of the Sommerfeld type and can be easily evaluated under the quasi-static approximation which is validated by the small dimensions relative to a wavelength. Enhancement of loop inductance by inclusion of a magnetic layer is investigated. It is shown that such a layer can increase the inductance by a percentage which has the upper limit of [(μr-1)/(μr+1)]×100%, where μr is the relative permeability of the layer. A study is also made on the inductor quality factor (Q) as affected by losses caused by finite electrical conductivity of the magnetic layer and the underlying substrate View full abstract»

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  • Open- and short-circuit terminated series stubs in finite-width coplanar waveguide on silicon

    Page(s): 970 - 976
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    Open- and short-circuit terminated series stubs in finite-width coplanar waveguide (FCPW) fabricated on high-resistivity Si are experimentally characterized over the frequency range of 2-40 GHz. In coplanar waveguide (CPW), these stubs are typically placed in the center conductor, but in FCPW, the stubs may also be placed in the ground planes resulting in novel circuit elements with characteristics that make the stubs useful for matching circuits and filters. Equivalent circuit models for the stubs are presented, and it is shown that when the stub is in the ground plane the resonant frequency is equal, the inductance and resistance is halved, and the capacitance is double the values of the same stub in the center conductor. Furthermore, it is shown that by varying the stub position in the ground plane, higher Q stubs can be obtained View full abstract»

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  • Millimeter-wave amplitude-phase modulator

    Page(s): 911 - 917
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    A millimeter-wave amplitude-phase modulator, using Fox's (polarization) principle of phase changing has been developed. Using this modulator, it is possible to perform the following types of phase modulation: binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), differential QPSK (DQPSK), π/4-DQPSK with peak phase error 5° (rms error: 2°), and peak amplitude error 2% (rms error: 1%) in the frequency range of 36-37.5 GHz. The achievable switching time is less than 35 ns. A low level of insertion loss (1 dB) is achieved. The modulator is able to switch up to 25 dBm of RF power. This modulator can also be used for changing the amplitude of the output wave from 0 to -6 dB with an accompanying phase modulation less than 3°. The modulator is suitable for use in high-speed millimeter-wave communication systems View full abstract»

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  • A modified Chebyshev bandpass filter with attenuation poles in the stopband

    Page(s): 898 - 904
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    This paper describes a design method of a modified Chebyshev bandpass filter with attenuation poles in the stopband. The insertion of attenuation poles into resonators in the authors' bandpass-filter design is accomplished by connecting a lumped inductor or capacitor in series with a shunt-type coaxial transmission-line resonator. The inserted poles which are distributed over the stopband can be chosen such that the insertion loss of the filter has equiripple characteristic and maximum attenuation in the stopband with the given number of attenuation poles. The modified Chebyshev bandpass filter designed by this method can be effectively used in diplexer design View full abstract»

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  • Hybrid integration technology of planar circuits and NRD-guide for cost-effective microwave and millimeter-wave applications

    Page(s): 946 - 954
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    An architecture called the hybrid planar/non-radiative-dielectric (NRD) waveguide integrated technology is proposed as a building block for constructing microwave and millimeter-wave circuits. This hybrid approach of integration offers a unique possibility of exploiting inherent complementary advantages of planar structures and NRD waveguides for low-cost wireless applications while eliminating the potential drawbacks associated with both dissimilar structures. Compared to the existing NRD-guide related technology, the proposed framework consists of relocated planar structures on the top and/or the bottom plates of an NRD-guide, sharing the common ground planes. Such a hybrid scheme is particularly suitable for millimeter-wave systems in which active devices can be made with the planar-line technique while passive components can be made with the NRD-guide technique. The two subsets of a complete functional system are interconnected through a class of aperture-based transitions which can be designed to have wide-band performance. In addition, the multichip module (MCM) technique is readily achieved under this proposed scheme. Experimental prototypes, including passive-component and active-device, based on the new hybrid technology presented in this paper, show that the novel hybrid technology promises to be useful in the design of future microwave and millimeter-wave circuits and systems View full abstract»

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  • DC to high-frequency HBT-model parameter evaluation using impedance block conditioned optimization

    Page(s): 886 - 897
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    A new heterojunction bipolar transistor (HBT) small-signal equivalent-circuit parameter-extraction procedure employing multibias S-parameter data is presented. The algorithm combines analytical and empirical parameter evaluation techniques and results in a bias-dependent HBT model. To minimize the risk of nonphysical parameter estimation, elements such as the DC transport factor, αo, and the emitter-base conductance are evaluated from the device DC characteristics, and the frequency dispersion of α is related to the RC time-constant of the emitter-base junction. Moreover, initial values for the extrinsic device parasitics are obtained from “hot” as well as “cold” S-parameter data. The method results in excellent fit between measured and modeled S-parameter data in the frequency range DC-40 GHz and for a wide range of bias operating points View full abstract»

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  • Quasi-static design technique for MM-wave micromachined filters with lumped elements and series stubs

    Page(s): 931 - 938
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    This paper describes micromachined, membrane-supported low-pass and bandpass filters which are suitable for microwave and millimeter-wave (MM-wave) application. The designs are realized in coplanar-waveguide (CPW) form using short- and open-end series stubs with integrated metal-insulator-metal (MIM) capacitors, and are compact in lateral and longitudinal dimensions. A computationally efficient analysis has been developed for the design and characterization of the filters. The technique is based on a quasi-static coupled-line (CL) treatment of the series stubs, and uses normal mode impedance parameters, which are calculated with the spectral-domain approach (SDA). Due to the broad TEM-bandwidth of the membrane-supported transmission lines, the method can accurately predict filter responses well into the rejection band. To demonstrate the above claims, the measured and simulated S-parameters of a 0.3 mm ×2.2 mm low-pass filter with a cutoff frequency at 17 GHz, and a second passband at 115 GHz, are presented. The new approach is also used in the design of bandpass filters which exhibit 1.5-2-dB insertion loss and bandwidths around 10% View full abstract»

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  • Solving microstrip discontinuities by the measured equation of invariance

    Page(s): 877 - 885
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    The measured equation of invariance (MEI) is a newly developed computational method which allows finite-difference (FD) or finite-element (FE) mesh to be terminated very closely to objects of interest. In this paper, the authors show how the MEI method may be applied to microstrip antennas and discontinuity problems. The authors demonstrate its use in general full-wave three-dimensional (3-D) microstrip problems, and give results for open-ended microstrip lines and microstrip bends View full abstract»

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  • Nonlinear surface waves on the interface of two non-Kerr-like nonlinear media

    Page(s): 924 - 930
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    In recent years, there has been growing interest in studying nonlinear guided-wave propagation as they present potential, yet not fully-explored, applications for high-speed optical signal processing and transmission. In this paper, analytical solutions for nonlinear surface waves on the interface of two nonlinear non-Kerr-like media are derived. The dispersion relations and their relations to the transmission power and initial field distributions are calculated. Several observations are made on the behaviors of the surface waves and their potential applications View full abstract»

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  • Finite-difference approach to the solution of time-domain integral equations for layered structures

    Page(s): 984 - 990
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A numerical algorithm for the analysis of transient electromagnetic fields in planar structures is proposed based on the time-domain magnetic-field integral equation (MFIE), electric-field integral equation (EFIE), and the marching-on-in-time approach. The field vectors are represented in terms of vector potential functions which are calculated either by integration or by the three-dimensional (3-D) wave equation according to the geometry of the structure. Thus, the algorithm combines the advantages of integral equation techniques and finite-difference schemes. While this approach is applicable to any geometries, it is especially suitable for multilayered planar structures and is competitive to the finite-difference time-domain (FDTD) method in the case of open and radiating problems. Theoretical results are verified by the analysis of a pulse propagation in a homogeneous open-end microstrip line View full abstract»

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  • Analysis and measurement of mode polarizers in square waveguide

    Page(s): 997 - 1000
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    A general analysis approach for strip metallization structures enclosed in rectangular or square waveguide is presented. The technique involves the novel application of a commercially available 2.5-dimensional (2.5-D) method-of-moments-based (MoM) electromagnetic (EM) analysis tool to a three-dimensional (3-D) waveguide problem. Very good agreement is demonstrated between computed and measured results for several printed strip linear polarizers embedded within a square waveguide environment. This paper, to the authors' knowledge, represents the first such comparison of phase and magnitude between computed and measured data for strip grid polarizers in a waveguide environment. The developed approach involves construction of a theoretical waveguide “test fixture” and an associated theoretical de-embedding procedure. Computational advantages are expected over the alternative approach of using a finite-element-based fully 3-D analysis approach. The polarizer results have potential application to shielded versions of quasi-optic array components that have been demonstrated in open geometries, as well as to multimode antenna feeds, waveguide filters, and matching networks View full abstract»

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  • A wide-band microwave photonic phase and frequency shifter

    Page(s): 1003 - 1006
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    Advanced radar deception systems require wide-band devices which perform microwave processing of frequency and phase information. A wide-band microwave photonic phase shifter was constructed which is capable of imposing greater than 2π phase shift to microwave signals in the 2-18-GHz frequency range. The maximum standard deviation from the phase setting was 10° (7° typical). The phase shifter was then incorporated into a frequency translation architecture. The carrier suppression obtained was 50 dB with a spurious harmonic suppression of 23 dB View full abstract»

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  • Investigation and modeling of impact ionization with regard to the RF and noise behavior of HFET

    Page(s): 977 - 983
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    A new small-signal and noise-equivalent circuit for heterostructure field-effect transistors (HFET's), including the influence of impact-ionization and gate-leakage current on the electronic properties, is presented. The capability of the new model is demonstrated by bias-dependent investigations of the high-frequency (HF) (45 MHz up to 40 GHz) and noise behavior (2 GHz up to 18 GHz) of the InAlAs/InGaAs/InP HFET. Furthermore, based on these results, the bias-dependence of the newly implemented small-signal equivalent elements and the equivalent intrinsic noise sources, are discussed View full abstract»

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  • Study of a combined millimeter-wave resonator

    Page(s): 1000 - 1002
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    We present a theoretical investigation and measurements of a multielement open resonator composed of corrugated waveguides and plane semitransparent reflectors. A periodic-transmission-line model is used to analyze the transverse mode structure and the diffraction Q-factor of the proposed resonator. The setup containing the resonator (equipped with Bragg reflectors), mode converters, and an elliptical mirror is employed for measurements in Ka-band. Two- and three-waveguide-section resonators have been studied. The proposed resonators demonstrate good mode selectivity that permits one to utilize them in high-power millimeter-wave sources 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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