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Microwaves, Antennas and Propagation, IEE Proceedings

Issue 3 • Date Jun 2001

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Displaying Results 1 - 15 of 15
  • Analysis of a ridged circular disc microstrip antenna element using the cavity model

    Page(s): 213 - 217
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    A theoretical analysis of a ridged circular patch microstrip antenna element is presented by modelling it as a cylindrical cavity with a magnetic wall along its edge. The approach is based on conserving the reaction at the ridged position. This antenna, excited in the dominant mode, resonates at higher frequencies and has a wider bandwidth than a simple conventional circular patch antenna with the same size. Design graphs show the variation of the resonant frequency, quality factor, radiation efficiency, feeding position at resonance and bandwidth (VSWR ⩽2), for the dominant mode as a function of the ratio of inner to outer-disc radius for different ridge thicknesses View full abstract»

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  • Effect of superstrate on radiated field of probe fed microstrip patch antenna

    Page(s): 141 - 146
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    A dielectric superstrate with a high permittivity can be used to enhance the gain of a microstrip antenna. The effect of the superstrate is investigated experimentally in the case of a probe fed microstrip patch antenna. The measured radiation properties of the antenna structure are discussed in terms of an increasing spacing between the patch and the superstrate. The well known theoretical resonance conditions are clearly illustrated. The phenomenon of the splitting of the main beam is observed View full abstract»

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  • Scaling-function based multiresolution time domain analysis for planar printed millimetre-wave integrated circuits

    Page(s): 179 - 187
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (924 KB)  

    The paper applies a scaling-function based multiresolution time domain (MRTD) scheme, in conjunction with an anisotropic perfectly matched layer (APML) for open and PEC-shielded boundary truncations, to analyse various planar millimetre-wave integrated circuits (MICs). Although adding complexity in deriving update equations and extracting MIC characteristics compared with the conventional finite difference time domain (FDTD) method, the MRTD scheme does provide a systematic, constructive, and flexible tool for the analysis of practical planar printed MIC structures. In particular, it is shown that the MRTD scheme is very efficient and requires only about 15% of the computational space and 25% or less of the time needed for the conventional FDTD techniques for all structures investigated in this research View full abstract»

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  • Application of FDTD method to conformal patch antennas

    Page(s): 218 - 220
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The paper presents an application of the conformal finite difference time domain (CFDTD) method to model a conformal patch antenna mounted on a coated PEC cylinder. A conformal technique and non-uniform mesh are used to model the entire antenna configuration including the PEC cylinder, the thin dielectric layer and the patch antenna, as opposed to a hybrid approach, which is sometimes used to solve this type of problem View full abstract»

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  • Reduction of drift error of a network analyser in small antenna measurement

    Page(s): 188 - 192
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    The radiation resistances of electrically small antennas are precisely measured on the basis of the Wheeler cap method, reducing drift error, which is due to thermal fluctuation of components of a network analyser, by using a double-stub tuner. For the first time in antenna measurements, quantitative consideration of the reduction of the drift error for the network analyser is conducted. Also, time fluctuation of the drift error is characterised with a vector diagram to find an effective method for the drift error reduction. As a result, the measurement precision of the antenna with a very large input reactance (more than 180Ω in its absolute value) is considerably improved using the stub tuner View full abstract»

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  • Global modelling of microwave active circuits by an efficient iterative procedure

    Page(s): 209 - 212
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    A new rigorous iterative process is proposed for studying a rectangular waveguide which includes the Gunn diode GaAs AH445 (THOMSON). It consists in generating a recursive relationship between a given wave source and reflected waves from the discontinuity plane which is divided into cells. A high computational speed has been achieved by using fast mode transformation (FMT). The theory as well as its implemention procedure are described. Numerical results are successfully compared with experimental published data View full abstract»

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  • Single-layer miniature broadband microstrip antenna using wirebonding technique

    Page(s): 199 - 202
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A wirebonding technique is presented for designing a single-layer miniature and broadband microstrip antenna on the basis of experiments. The technique most commonly applied in device assembly will support manufacturing and packaging of small antennas by avoiding via-holes. Consisting of three short-circuited elements fed by a parasitic wirebonding configuration, the antenna in a package format has the merits of wide impedance bandwidth, miniature structure, flexible matching and easy integration into RF front-end units. Its stable and broadside copolarised radiation patterns in the frequency range of 2.40-2.51 GHz are satisfactory for Bluetooth application View full abstract»

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  • Accurate FDTD wavelet-Galerkin representation of field singularities near conductive wedges

    Page(s): 163 - 166
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    A novel hybrid technique for the precise representation of field singularities generated by hard to model geometrical peculiarities, such as arbitrarily angled conductive wedges, is presented. Its primary concept lies in the combined implementation of the FDTD method and the wavelet (Daubechies' basis)-Galerkin formulation in different, distinct areas of the computational domain. The robustness and simplicity of the former, used in regions of smooth field variations, and the ability of the latter, utilised near discontinuities, to efficiently simulate highly varying phenomena, allow the precise treatment of sharp wedges. Hence, the proposed algorithm yields sufficiently accurate coarse grid results and short time-advancing intervals, as the numerical verification reveals View full abstract»

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  • Accurate non-uniform transmission line model and its application to the de-embedding of on-wafer measurements

    Page(s): 153 - 156
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    An accurate model for lossy non-uniform transmission lines is presented. The technique provides a coplanar waveguide (CPW) taper model, which has been used to accurately de-embed measurements of passive CPW components in line geometries differing from the nominal 50Ω geometry of the calibration. The model accounts for both dielectric and conductor losses, and is shown to be in excellent agreement with measured results from 45 MHz to 120 GHz View full abstract»

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  • Analysis of Rotman lenses using a hybrid least squares FEM/transfinite element method

    Page(s): 193 - 198
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (916 KB)  

    A hybrid procedure that combines the least squares finite element method (LSFEM) and the transfinite element method is applied to the analysis of multiport Rotman lenses. The LSFEM is employed to build a functional based on the L2-norm of the residuals of the full first-order Maxwell equations governing the electromagnetic fields in the structure. Because the full first-order Maxwell equations are solved, the method is free from spurious solutions. The transfinite element method is used to transfer the exterior conditions in the port regions to the interior region. The method is applied to a Rotman lens to determine the field distribution in the lens and the scattering parameters. Measured results for a microstrip Rotman lens with nine beam ports and eight array ports show good agreement with theoretical predictions View full abstract»

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  • Study of out of plane bistatic scattering from rough dielectric surfaces

    Page(s): 157 - 162
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    The paper examines the like- and cross-polarised bistatic scattering characteristics from random rough surfaces along the azimuth angle. To compare the contributions of single and multiple scattering, it studies the effect of multiple scattering under different surface parameters. The single cross-polarised scattering coefficient vanishes in the plane of incidence, but the single like-polarisations reach their minima near 90° from the incident plane. The multiple scattering therefore shows the significant contribution to the cross-polarised scattering in the plane of incidence and the like-polarisations in the orthogonal plane. The model is evaluated by comparing the prediction with the measurement and demonstrates good agreement between the prediction and the experimental data for both like- and cross-polarised scattering coefficients View full abstract»

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  • Pattern shaping using a reactively loaded wire loop antenna

    Page(s): 203 - 208
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    A method for obtaining continuous beam steering of ±30° from bore-sight by reactively loading a one-wavelength square wire loop antenna placed over a ground plane is presented. By introducing a small gap at the middle of one of the two non-radiating sides, the phase difference of current on the two radiating sides of the wire loop can be adjusted. This is done by varying a single reactive load at the middle of the opposite non-radiating side. As a result, the far-field radiation pattern of the antenna can be controlled in the plane perpendicular to the radiating sides. The input VSWR for the arrangement is shown to be insensitive to loaded reactance variation. An analytical explanation for the behavior of the antenna is given, together with experimental verification View full abstract»

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  • Integrated multibeam dual-polarised planar array

    Page(s): 174 - 178
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    A novel four-beam dual-polarised microstrip antenna array at the 10 GHz band is presented. By using a multilayered structure and multiport slot-coupled microstrip lines, two Butler matrix microstrip circuits corresponding to two orthogonal polarisations can be located on different substrate layers (above and below the ground plane) and integrated with a patch array. The antenna has eight input ports corresponding to two orthogonal polarisations and four beams. The theoretical design is based on the finite-difference time-domain (FDTD) method. The measured return loss and isolation characteristics exceed 10 and 23 dB, respectively, in the 9.7-10.3 GHz band. The radiation pattern is close to an ideal Butler pattern and the cross-polarisation level is lower than -18 dB in the beams. Details of the antenna and its characteristics are presented View full abstract»

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  • Cavity model of circularly polarised cross-aperture-coupled microstrip antenna

    Page(s): 147 - 152
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    A cavity model is used to analyse an aperture-fed nearly square circularly polarised patch antenna. The form of the aperture is that of a symmetric cross-slot that couples the excitation between a single microstrip feed line and the patch antenna. Using equivalent magnetic current sources at the slots, the modal electric and magnetic fields under the patch are obtained, and hence analytical expressions for the patch admittances at the aperture are derived and used to obtain an equivalent circuit of the circular polarised antenna. Good agreement is obtained between the circuit modelling and practical results View full abstract»

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  • Effects of gaps and bypass capacitors on interconnect of PCB with multilayered geometry

    Page(s): 167 - 173
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    A microstrip with gap discontinuity and bypass capacitors on the ground plane for interconnects in multilayered digital circuits is analysed. The approach is based on integral equations using the spatial-domain magnetic field Green's function in a layered medium. The method of moment solution is obtained with RWG basis functions and Galerkin testing. The method is applied to gaps with bypass capacitors in single and double layer structures. Simulation results are obtained for various values and locations of bypass capacitors and for the case of a second reference plane. The effects of bypass capacitors and a second reference plane are analysed based on the simulation results. Numerical results give a quantitative description of the reduction in inductance created by the gap with bypass capacitors and a second reference plane View full abstract»

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