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Microwave Theory and Techniques, IEEE Transactions on

Issue 5 • Date May 2003

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Displaying Results 1 - 25 of 26
  • Rapid coupling matrix reduction for longitudinal and cascaded-quadruplet microwave filters

    Page(s): 1578 - 1583
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    To realize standard microwave filter structures, it is necessary to zero some of the elements in a general even-mode coupling matrix. The zeroing process involves solving a nonlinear set of equations, performed here by using the Newton-Raphson method. Thus, intelligence is added to the numerical iteration procedure, to ensure rapid convergence. The reproduced transmission coefficient S21 from the reduced matrix agrees well with the one synthesized. View full abstract»

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  • 2-D localization and identification based on SAW ID-tags at 2.5 GHz

    Page(s): 1584 - 1590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    An identification and localization system based on surface acoustic wave (SAW) radio sensors is presented in this paper. This system is able to identify and localize objects within a two-dimensional area. Identification is achieved with a fixed coded passive SAW identification-tag. Localization is carried out with three receiving antennas and with a following analysis of time delay between the sent interrogation signal and the received signals. For practical tests, a special interrogator has been established, as well as the receiving and demodulation unit. The whole system is controlled by a computer. View full abstract»

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  • Intrinsic noise equivalent-circuit parameters for AlGaN/GaN HEMTs

    Page(s): 1567 - 1577
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (765 KB) |  | HTML iconHTML  

    Intrinsic noise sources and their correlation in gallium-nitride high electron-mobility transistors (HEMTs) are extracted and studied. Microwave noise measurements have been performed over the frequency range of 0.8-5.8 GHz. Using measured noise and scattering parameter data, the gate and drain noise sources and their correlation are determined using an equivalent-circuit representation. This model correctly predicts the frequency-dependent noise for two devices having different gate length. Three noise mechanisms are identified in these devices, namely, those due to velocity fluctuation, gate leakage, and traps. View full abstract»

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  • An analysis of small-signal substrate resistance effect in deep-submicrometer RF MOSFETs

    Page(s): 1534 - 1539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    Two different explanations of the S22 kink phenomenon in deep-submicrometer RF MOSFETs have been reported: Hjelmgren and Litwin (see IEEE Trans. Electron Devices, vol.48, no.2, p.397-399, 2001) attributed the phenomenon to the substrate resistance, while Lu et al. (see ibid., vol.49, no.2, p.333-340, 2001) concluded that it results from the transconductance, or simply speaking, the size of the transistor. In this paper, we extend the dual-feedback circuit methodology for the three-terminal FET model proposed by Lu et al. into a more general four-terminal model in order to account for the influence of the substrate resistance. Our results show that, for a given MOSFET, either substrate resistance or transconductance may cause a kink in S22. In addition to the single kink, which results from the above two factors, the double kinks, which appear when the substrate resistance of a MOSFET is within a middle range (approximately 102 to 104 Ω), can also be accounted for by our extended model. Experimental data representative of 0.25 μm gate MOSFETs are adopted to verify our theory. Excellent agreement between theoretical values and experimental data has been found, which indicates our theory can successfully explain the S22 kink phenomenon in deep-submicrometer RF MOSFETs. View full abstract»

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  • 5.8-GHz circularly polarized dual-rhombic-loop traveling-wave rectifying antenna for low power-density wireless power transmission applications

    Page(s): 1548 - 1553
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    This paper reports a right-hand circularly polarized (RHCP) high-efficiency traveling-wave rectifying antenna (rectenna) designed in a coplanar stripline (CPS) circuit that is etched on a Rogers Duroid 5870 substrate with εr=2.2 and 20-mil thickness. A 4 × 1 traveling-wave array of RHCP high-gain dual-rhombic-loop antennas (DRLAs) and a reflecting plane are used to provide highly efficient RF-to-DC conversion in the presence of lower power densities regardless of the rectenna's broadside orientation. The DRLA array has a circularly polarized antenna gain of 14.6 dB with a 2:1 voltage standing-wave ratio bandwidth of 17% and a better than 3 dB axial ratio fractional bandwidth of 7% centered about 5.8 GHz. The rectenna achieves 82% RF-to-DC conversion efficiency at 5.8 GHz and uses a low-profile CPS band-reject filter to suppress the re-radiated second harmonic by over 14 dB. The rectenna operating at low power density should have many applications when the transmitting power is low and/or the transmission distance is long. View full abstract»

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  • Analysis and reduction of cross-modulation distortion in CDMA receivers

    Page(s): 1591 - 1602
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (893 KB) |  | HTML iconHTML  

    The jammer cross modulation (XM) transferred from a transmitter (TX) CDMA leakage by a receiver circuit is analyzed using the Volterra series and statistical theory. The measured "double-hump" XM spectrum is explained based on the CDMA signal statistics derived using the proposed system model of a reverse-link CDMA signal. The analysis shows that the XM distortion is affected by the circuit behavior not only at the jammer and the TX leakage frequencies, but also in the CDMA signal baseband and at the sum and difference of the excitation frequencies. This theory was verified on a 2-GHz Si bipolar junction transistor low-noise amplifier whose out-of-band terminations were optimally tuned to significantly reduce its XM distortion. View full abstract»

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  • Finite-difference analysis of a loaded hemispherical resonator

    Page(s): 1506 - 1511
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    A rotationally symmetric inhomogeneously loaded open hemispherical resonator is analyzed using the finite-difference (FD) frequency-domain method. State-of-the art or new techniques are proposed to achieve high accuracy and efficiency of computations. These include applying the Galerkin method followed by an inexact shift-and-inverse Lanczos technique with an approximate starting eigenvector for selective computation of a single desired high-order mode, and compensating numerical dispersion error with the modified FD formulas. As a result, the final value of the computed resonant frequency for a desired mode agrees within 0.1% with the measured value and the computations involving a few 100000 unknowns are carried out in minutes on a personal computer. View full abstract»

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  • Modified transmission-reflection method for measuring constitutive parameters of thin flexible high-loss materials

    Page(s): 1560 - 1566
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (703 KB) |  | HTML iconHTML  

    The transmission-reflection method is modified for measuring constitutive parameters of thin high-loss materials used as radar absorbers. The method uses a two-layer structure, consisting of a layer of thin flexible unknown material supported by a thicker rigid known material. The analysis and measurements focus on nonmagnetic samples of a high dielectric constant and loss factor and on the waveguide configuration in the X-band. A nonlinear least-squares optimization is used to obtain the complex permittivity from the measured scattering parameters. The uncertainty analysis presented facilitates selection of the support layer thickness. Simulations with the finite-difference time-domain method explore the effects of sample imperfections. Accuracy of a few percent can be achieved for a sample thickness of a fraction of a millimeter, provided that the thickness of the support dielectric is close to optimum and sample has only small surface imperfections. View full abstract»

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  • Microwave characterization of a microstrip line using a two-port ring resonator with an improved lumped-element model

    Page(s): 1540 - 1547
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (467 KB) |  | HTML iconHTML  

    A two-port ring resonator is used to characterize the microwave properties of a microstrip line printed on Ferro A6-S low-temperature co-fired ceramic. The ring and its coupling gaps are simulated using a simple lumped-element model. The coupling gaps are modeled as capacitors, the values of which are extracted using a commercial two-and-one-half-dimensional electromagnetic simulator. The validity of the lumped-element model is assessed by comparing the simulated and experimental resonant frequencies and, for the first time, the simulated magnitudes of both the reflection and transmission coefficients are also compared with those obtained experimentally. A correction for the frequency pushing due to the capacitive loading of the coupling gaps is also presented. The resulting model is then shown to predict the resonant frequencies to within 0.11% from 5 to 40 GHz. The simulated and experimental reflection magnitudes are within 0.5 dB across the band, whereas the transmission magnitudes are within 3.5 dB up to 22 GHz. Experimental results indicate that the loss of the microstrip ranges from approximately 0.11 to 0.42 dB/cm across the band and that the relative permittivity of the substrate is nearly constant versus frequency with an average value of 6.17. View full abstract»

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  • Measurements of a leaky-wave ferrite isolator

    Page(s): 1476 - 1481
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (433 KB) |  | HTML iconHTML  

    A single ferrite/dielectric image line is analyzed using the effective permittivity method adapted for ferrites. Epqx modes are used in association with a transverse bias direction to obtain nonreciprocal behavior. It is shown that the required conditions can be obtained that enable the composite image line to guide in one direction and leak in the other. Thus, the structure behaves as a "leaky-wave isolator." Dispersion diagrams showing this behavior in the frequency range of 14-30 GHz are obtained for a 2 × 2 mm2 ferrite (type TT1-390) rod with adjacent dielectric loading with εr=10. The structure is built and the bias is applied externally in a direction transverse to and in the plane of the direction of propagation. The required modes are excited and probed by semirigid coaxial cables mounted on vernier mechanisms. The S-parameters indicating the nonreciprocal behavior in the frequency range expected are shown. View full abstract»

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  • A new multiple-tuned six-port Riblet-type directional coupler in rectangular waveguide

    Page(s): 1441 - 1448
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (561 KB) |  | HTML iconHTML  

    Directional couplers are fundamental components for the realization of power splitting and combining networks. A basic component is the four-port coupler realized in a wide range of different electrical and geometrical configurations. Using multiport directional couplers, with six or more ports, compact power splitting and combining networks can be designed. Most of the multiport directional couplers in a rectangular waveguide found in literature use an E-plane branch-line layout. A special configuration of a six-port narrow-wall short-slot directional coupler (Riblet type) is presented here. The coupler has only one central coupling region, following the Riblet concept based on the differences among the propagation constants of the modes through the coupling region. A number of different solutions have been investigated and some examples are presented here. Moreover, a multituning realized by using input resonators permits one to significantly enlarge the bandwidth. A six-port coupler equally splitting on the output ports the power injected at each input port has been designed for a 8.4% working band. The theoretical and measured responses presented here prove the effectiveness of the multituning concept. View full abstract»

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  • Integrated antenna with direct conversion circuitry for broad-band millimeter-wave communications

    Page(s): 1482 - 1488
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB) |  | HTML iconHTML  

    A compact integrated antenna with direct quadrature conversion circuitry for broad-band millimeter-wave communications is proposed. The conversion circuits include two even-harmonic mixers based on antiparallel diode pairs (APDPs). The equivalent circuit of the APDP derived here provides good agreement with the measured data from 17 to 23 GHz. Overall phase and amplitude imbalance between the in-phase/quadrature (I/Q) output channels are less than 1.2° and 1 dB at IFs of 10 and 100 MHz, respectively. An overall RF power conversion loss of 14.6 dB at the quadrature I/Q channels including the antenna is achieved in the frequency range from 39.75 to 40.25 GHz with a local oscillator (LO) power level of 11.8 dBm. LO leakages at 20 and 40 GHz are -31.5 and -44.8 dBm, respectively. In order to demonstrate the system capabilities for broad-band digital communication, a communication link is built with a pair of the proposed front-ends. Data transmission up to 1 Gb/s data rate for quadrature phase-shift keying modulation is demonstrated. View full abstract»

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  • Low conversion-loss fourth subharmonic mixers incorporating CMRC for millimeter-wave applications

    Page(s): 1449 - 1454
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    Low conversion-loss millimeter-wave fourth subharmonic (SH) mixer designs are proposed in this paper. A millimeter-wave (35 GHz) fourth SH mixer with four open/shorted stubs is designed and measured. The conversion loss is less than 15 dB within a 2.4-GHz bandwidth. The minimum loss is 11.5 dB at the center frequency. By replacing two of the shunt stubs with a dual-frequency in-line stub consisting of newly developed compact microstrip resonating cells (CMRCs), the performance of the SH mixer is improved significantly. At 35 GHz, the conversion loss of this new fourth SH mixer is as low as 6.1 dB with a 3-dB bandwidth of 6 GHz. The conversion loss in the whole Ka-band (26.5-40 GHz) is less than 16 dB. The proposed fourth SH mixer incorporating with CMRCs provides a low-cost high-performance solution for RF subsystem design. View full abstract»

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  • Volterra-mapping-based behavioral modeling of nonlinear circuits and systems for high frequencies

    Page(s): 1433 - 1440
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (615 KB) |  | HTML iconHTML  

    Presents and validates a discrete-time/frequency-domain approach to the problem of Volterra-series-based behavioral modeling for high-frequency systems. The proposed technique is based on the acquisition of samples of the input/output data, both of which are sampled at the Nyquist rate corresponding to the input signal. The method is capable of identifying the time-/frequency-domain Volterra kernels/transfer functions of arbitrary causal time-invariant weakly nonlinear circuits and systems operating at high frequencies subject to essentially a general random or multitone excitation. The validity and efficiency of the proposed modeling approach has been demonstrated by several examples in high-frequency applications and good agreement has been obtained between results calculated using the proposed model and results measured or simulated with commercial simulation tools. View full abstract»

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  • General relations between IP2, IP3, and offsets in differential circuits and the effects of feedback

    Page(s): 1610 - 1612
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    In the presence of offsets, all balanced circuits show an apparent second-order distortion. Differential feedback lowers third-order nonlinearity and also these second-order effects. The results are important for the baseband circuits of zero-IF wireless receivers, which often need a very large second-order intercept point. It is shown that a published analysis of distortion in a bipolar double-balanced mixer is a special case of these general relationships. View full abstract»

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  • W-band waveguide photomixer using a uni-traveling-carrier photodiode with 2-mW output

    Page(s): 1455 - 1459
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (657 KB) |  | HTML iconHTML  

    Developed a W-band (75-110 GHz) waveguide photomixer with a uni-traveling carrier photodiode, which can be driven by two 1.5-μm lasers. It generates an output power of 2.2±0.2 mW at 100 GHz with a laser power of less than 100 mW, and its relative power variation is as small as 3 dB across the entire frequency range of the W-band. A 100-GHz superconductor-insulator-superconductor receiver driven by this photomixer shows the same noise temperature around 26 K as that driven by a conventional Gunn oscillator. View full abstract»

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  • Millimeter-wave active imaging using neural networks for signal processing

    Page(s): 1512 - 1516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (359 KB) |  | HTML iconHTML  

    A neural network has been successfully implemented in an active-mode millimeter-wave (60 GHz) imaging system with a Yagi-Uda antenna array in order to recognize objects and reconstruct images that appear distorted under coherent millimeter-wave illumination. With 10 × 10 sampling points and five teaching trials, a recognition rate of 98% has been obtained for ten dissimilar alphabetical letters used as objects. The success rate of reconstruction of distorted millimeter-wave images was 80% when five dissimilar letters were used for the reconstruction. The recognition rate after changing the spatial resolution of the optical system and sampling interval of the image is also discussed. View full abstract»

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  • A broad-band LTCC integrated transition of laminated waveguide to air-filled waveguide for millimeter-wave applications

    Page(s): 1613 - 1617
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB) |  | HTML iconHTML  

    In this paper, a compact and broad-band integrated transition between laminated waveguide in a multilayer low-temperature co-fired ceramic (LTCC) substrate and standard air-filled rectangular waveguide is presented. A parallel inter-coupled two-pole filter equivalent circuit is employed to interpret the working mechanism of the transition and to predict the performance. A Ka-band prototype of the proposed broad-band transition is designed and fabricated in an LTCC substrate. The simulated and measured results of the prototyped transition show good agreement. It has been demonstrated, through the experimental results of the Ka-band prototype that the proposed transition configuration gives an effective bandwidth of over 8% with -15-dB return loss and average -0.4-dB insertion loss over the bandwidth at the Ka frequency band. View full abstract»

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  • Microstrip stepped impedance resonator bandpass filter with an extended optimal rejection bandwidth

    Page(s): 1554 - 1559
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    Bandpass filters with an optimal rejection bandwidth are designed using parallel-coupled stepped impedance resonators (SIRs). The fundamental (fo) and higher order resonant harmonics of an SIR are analyzed against the length ratio of the high-Z and low-Z segments. It is found that an optimal length ratio can be obtained for each high-Z to low-Z impedance ratio to maximize the upper rejection bandwidth. A tapped-line input/output structure is exploited to create two extra transmission zeros in the stopband. The singly loaded Q(Qsi) of a tapped SIR is derived. With the aid of Qsi, the two zeros can be independently tuned over a wide frequency range. When the positions of the two zeros are purposely located at the two leading higher order harmonics, the upper rejection band can be greatly extended. Chebyshev bandpass filters with spurious resonances up to 4.4fo, 6.5fo, and 8.2fo are fabricated and measured to demonstrate the idea. View full abstract»

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  • Characteristics of striplines with inhomogeneous cylindrical substrate

    Page(s): 1496 - 1505
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    A mode-matching technique combined with Galerkin's method is proposed in this paper to analyze the characteristics of striplines embedded in an inhomogeneous cylindrical medium. The potential in each layer is expressed in terms of eigenmodes obtained numerically. Coupling between two sets of eigenmodes in contiguous layers is described by defining potential ratio coefficient matrices. An integral equation is derived based on these eigenmodes with charge on the stripline as unknown. The method of moments is then applied to solve this integral equation. Various parameters are analyzed for their effects on transmission characteristics. View full abstract»

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  • Transmission-line filters with capacitively loaded coupled lines

    Page(s): 1517 - 1524
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (713 KB) |  | HTML iconHTML  

    Coupled lines with loads at one end, which can create tunable transmission zeros, are studied in this paper. The equation for the transmission zeros is derived from the analysis of even- and odd-mode excitations. Based on this equation, coupled lines with different loads are analyzed and the rules for controlling the transmission-zero frequency are given. The structures are used in the designs of several second-order filters and they are experimentally verified. The use of a skew-symmetric (0°) feed structure in these filters is also discussed and an example is given. View full abstract»

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  • Efficient calculation of the band structure of artificial materials with cylindrical metallic inclusions

    Page(s): 1460 - 1466
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    We present a new hybrid method that makes the calculation of the band structure of artificial materials with cylindrical metallic inclusions very efficient. We derive an auxiliary problem whose band structure is that of the metallic crystal along with several dispersionless bands. The eigenfunctions of the auxiliary problem have continuous derivatives up to order 2. Thus, the spectrum of the auxiliary problem can be efficiently computed using the plane-wave method. The band structure of the metallic crystal is then obtained by extracting from the computed results the dispersionless bands. View full abstract»

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  • A wide-band on-wafer noise parameter measurement system at 50-75 GHz

    Page(s): 1489 - 1495
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (427 KB) |  | HTML iconHTML  

    A wide-band on-wafer noise parameter measurement system at 50-75 GHz is presented. This measurement system is based on the cold-source method with a computer-controlled waveguide tuner. Calibrations and measurement methods are discussed and measured results for passive and active on-wafer devices are shown over a 50-75 GHz range. An InP high electron-mobility transistor device is used as a test item for the active device. A Monte Carlo analysis to study measurement uncertainties is also shown. The measurement system is a useful tool in the development and verification of device noise models, as well as in device characterization. View full abstract»

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  • Multiport scattering matrix measurement using a reduced-port network analyzer

    Page(s): 1525 - 1533
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB) |  | HTML iconHTML  

    A novel method for acquiring the scattering matrix of an n-port network from measurements using a reduced-port network analyzer is developed. This method can obtain the scattering matrix of a nonreciprocal or reciprocal n-port network with the use of a three- or two-port network analyzer. The formulation of this method considers the imperfection of terminators used in the measurement, and only two of the terminators are required to be known. Experimental results from a four-port microstrip circuit show good accuracy using the developed method. View full abstract»

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  • A microwave radar technique for dynamic testing of large structures

    Page(s): 1603 - 1609
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2149 KB) |  | HTML iconHTML  

    In this paper, the authors propose an innovative survey radar technique based on microwave holographic images for dynamic testing of large structures providing both vibration amplitude pattern and frequency. Theoretical background is provided and experimental results obtained during a dynamic test on a concrete and masonry building are reported. 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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