Phase characterization of ferromagnetic materials using a coplanar waveguide

Two different types of cavity backed four-arm slot like spiral antennas, fed through a metal backed coplanar waveguide (CPW), are presented in this paper. The spiral antennas are designed to operate between 1 and 3 GHz for normal (broadside) beam and split mode operation. A finite element - boundary integral (FE-BI) code is used to numerically analyze various antenna parameters. The antennas are built on a dielectric substrate with permittivity 2.2 and thickness of 0.0787 cm to fit in an 8.16/spl times/8.16/spl times/1.5 cm/sup 3/ cavity. Measured and computed data are presented and generally good agreement was obtained.

A laterally shielded coplanar waveguide consisting of a coplanar waveguide of finite width placed vertically in a cutoff parallel-plate waveguide is proposed for millimeter-wave applications. Advantages of the waveguide over the conventional coplanar waveguide are weak dispersion and low loss characteristics due to elimination of undesired surface waves and radiation. Simple but accurate analytical formulas for circuit design are derived and semi-empirical formulas for the weakly dispersive characteristics are also examined. Transitions to coaxial line are devised and the propagation constant is measured at millimeter wavelengths.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Finite-difference time-domain method is adopted in this paper to build models and simulate full-space coplanar waveguide and shielded coplanar waveguide. The propagation constant and characteristic impedance of coplanar waveguide in different models are obtained and compared with the results of traditional modeling. Finally, the effects of different modeling on electromagnetic characteristics of coplanar waveguide are presented.

A reconfigured slot-ring antenna fed by a coplanar waveguide (CPW) is proposed for the wireless local area network dual-band applications at 2.4 and 5.2 GHz bands. The slot-ring antenna together with its feeding structure has preserved a uniplanar configuration. The slot-ring is directly connected to a feeding CPW. The slot-ring&apos;s first and third resonant modes provide antenna&apos;s passband. The antenna&apos;s spurious modes are suppressed by adding to the slot-ring four metal strips at proper positions. An additional short-circuited CPW is stretched out from the end of the CPW feed, entering into the central circular patch of slot-ring to improve the impedance matching at 5.2 GHz frequency band. A pair of shunt slot tuning stubs, which are placed at the inner edge of the slot-ring, are used to tune the antenna&apos;s third resonant frequency to 5.2 GHz. This antenna has achieved fractional bandwidths of 7.5 and 10.4% at 2.4 and 5.2 GHz frequency bands, respectively. The return losses obtained are −30.56 dB at 2.4 GHz and −41.71 dB at 5.2 GHz. Details of the antenna designs and experimental results are presented and discussed.

This paper demonstrates the ink-jet printing of a coplanar waveguide (CPW) transmission line on Kapton™ and Willow Glass substrates for space electronics. A customized Nordson EFD fluid dispensing system with xQR41 Series Microdot™ needle valve was used to print CPW transmission lines using DuPont 5025 conductive paste with feature sizes approximately 200 μm. The printing challenges related to viscosity of ink, deposit size, and fluid inlet pressure were identified and solutions are provided. The characterization of the propagation constant and reflection coefficient of the CPW lines have been carried out using a multiline TRL calibration technique. Additionally, the PNA was calibrated to the probe tips using a GGB Picoprobe Short-Open-Load-Thru (SOLT) calibration standard wafer for measuring the CPW lines over a broader bandwidth (up to 50 GHz). The RF power handling capability and the adhesion tape testing results of the CPW lines are also presented. At 10 W input power, the Kapton bent upwards and the CPW line discolored. Despite all these observed variations, the CPW line operated well.

This paper presents the characteristics of coplanar waveguides (CPW) on silicon substrates fabricated through the MCM-D process. The propagation constant and characteristic impedance are measured at frequencies from 0.05 GHz to 10.05 GHz, using a vector analyzer, and with LRRM on-wafer calibration techniques followed with a de-embedding procedure. Two quasi-TEM models are developed to account for the EM affects in the CPW structure: the distributed equivalent elements RLGC were modeled by both closed-form approximation and fully lumped-equivalent circuits. The calculated characteristics show good agreement with the measured ones. The proposed models should be useful for the analysis and design of RFIC on silicon.

An electromagnetic solution with finite element boundary integral (FEBI) method and multilevel complex source beam (MLCSB) method, which is referred to as FEBI-MLCSB, is proposed for analyzing composite metallic and material objects. The MLCSB method and the translation invariance of the dyadic Green's functions are derived into the boundary integration equation (BIE) to reduce the memory requirement and accelerate the solving process. Numerical results show the efficiency of the proposed method.

The radiation characteristics of a two-element array of equilateral triangular patch microstrip antenna on a ferrite substrate are studied theoretically by considering the presence of bias magnetic field in the direction of propagation of electromagnetic waves. It is found that the natural modes of propagation in the direction of magnetic field are left- and right-circularly polarized waves and these modes have different propagation constants. In loss-less isotropic warm plasma, this array antenna geometry excites both electromagnetic (EM) and electroacoustic plasma (P) waves in addition to a nonradiating surface wave. In the absence of an external magnetic field, the EM- and P-waves can be decoupled into two independent modes, the electroacoustic mode is longitudinal while the electromagnetic mode is transverse. The far-zone EM-mode and P-mode radiation fields are derived using vector wave function techniques and pattern multiplication approaches. The results are obtained in both plasma medium and free space. Some important antenna parameters such as radiation conductance, directivity and quality factor are plotted for different values of plasma-to-source frequency.

A compact design of dualband strip antenna for 2.4/5 GHz WLAN communication is proposed. Printed on a thin soft laminate dielectric substrate and easily fed by using a coplanar waveguide (CPW) stripline, a small, low-profile, and flexible antenna structure with two meandered strips, capable of generating two separate resonant modes accompanied with 60% of size reduction compared with the reported one, is achieved. Prototypes of the proposed antenna have been constructed and tested. The obtained impedance bandwidths reach about 14% for the 2.4 GHz band and 23% for the 5 GHz band, which meet the required bandwidth specification of 2.4/5 GHz WLAN standard. Also, good radiation performance and antenna gain (≥2 dBi) over the two frequency ranges have been obtained.

We report on the application of Si and Al ion-implantation patterning to the fabrication of low-loss microwave transmission lines in high-temperature superconductor (HTS) thin films. Using this technique, we have fabricated coplanar waveguide (CPW) transmission lines in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films deposited on LaAlO/sub 3/ substrates. We have used both resonant and broadband measurements in order to characterize the performance of the resulting transmission line structures. For the broadband measurements, on-wafer calibrations were used to obtain accurate S-parameters and transmission line propagation constants up to 25 GHz. The propagation constants of the ion-implanted transmission lines do not differ significantly from those of lines patterned using conventional ion milling over the frequency range studied, with a value for the attenuation constant of approximately 0.03-0.04 dB/cm at 50 K and 10 GHz. The relatively low losses of the ion-implanted devices demonstrate the effectiveness of this method of patterning for HTS microwave device fabrication.

A dual-band coplanar waveguide (CPW) fed folded printed pseudo-monopole antenna (PPMA) of T-shape having 5.4% bandwidth (BW) at 1.5 GHz and 54% BW in the 3.5 GHz bands is proposed for LTE/WLAN/WiMAX. Not only the T-shaped PPMA is more compact than the standard PPMA, but also the capacitive loading, caused by the folding of the strip, is shown to improve the impedance matching, where two resonances due to two higher order modes provide a wide return loss BW at the 3.5 GHz band. Further, the concept is extended to design of a compact Yagi-type MIMO antenna, where two oppositely oriented T-shaped PPPMAs are separated by a common reflector to achieve a good isolation (|S21|≤ − 24 dB) between the feeding ports and to provide radiation pattern diversity.

The voltage standing wave on a coplanar waveguide (CPW) is measured at W-band (75–110 GHz) using an array of bismuth microbolometers placed over the CPW. From this information, the impedance at the end of the line can be determined in addition to the complex propagation constant of the CPW. This measurement technique should also be applicable for other planar transmission lines and be extendable above 110 GHz. This work represents the highest frequency, direct measurement of a VSW on a CPW made to date.

Summary form only given. Numerical analysis of electromagnetic scattering has been widely studied in the past. The method of moments (MoM) is suitable to simulate scattering from an object in an open region. In order to solve problems with complicated geometries and materials, the finite element method (FEM) is preferred. However, when solving unbounded problems with FEM, the use of absorbing boundary conditions or perfectly matched layers will result in truncation errors. To combine the advantages of both MoM and FEM, the finite element-boundary integral (FE-BI) method was developed and widely used (J. M. Jin, The Finite Element Method in Electromagnetics, Second Edition. New York: Wiley, 2002). This algorithm is not only able to deal with highly complicated geometry and material, but also able to eliminate the truncation error. However, since the MoM has O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2)</sup> computational and storage complexities, the computational cost of the BI-related algorithm is still prohibitively high when solving large-scale scattering problems. To alleviate this problem, the multilevel fast multipole algorithm (MLFMA) has been incorporated into the FE-BI method (J. Liu and J. M. Jin, IEEE Trans. Antennas Propag., vol. 51, pp.1157-1167, Jun. 2003). Another important technique to accelerate the computation is to resort to parallel computers. Recently, the graphics processing unit (GPU), as one of many-core computing systems, has received intensive attention from the scientific computing community due to its low price, a massive number of processors, and the resulting high computational efficiency. In this work, we discuss the GPU implementation of the FE-BI algorithm for solving electromagnetic scattering problems. First, the assembly of the BI-related matrix is parallelized on GPU by NVIDIA's compute unified device architecture (CUDA). A massive number of threads are assigned to carry out the assembly, and each thread computes one element in the BI-related matrix. Second, both the direct and iterative solvers are implemented on GPU. For the direct solver, the Intel's math kernel library (MKL) is used for LU decomposition, and the CUSPARSE (a set of basic linear algebra subroutines used for handling sparse matrices) is employed to speedup forward and backward substitutions. For the iterative solver, the high performance CUDA Basic Linear Algebra Subprograms (BLAS) is utilized for the matrix-vector multiplication and the vector-vector multiplication. Extensive numerical experiments are conducted to validate the implementation and demonstrate the achievable computational speedup.

By virtue of their low operation count, the application of fast integral methods such as the fast multipole (FMM) and adaptive integral methods (AIM) result in a substantial quickening of the boundary integral portion of the hybrid finite element-boundary integral (FE-BI) method, independent of the shape of the BI contour. Recently, various versions of the FMM have been proposed, each introducing a different approximation to the implementation of the boundary integral. The main goal of this Letter is to provide a comparison of the effect of these fast integral algorithms on the boundary integral when used in conjunction with the traditional FE-BI method.

This paper addresses the time-harmonic, electromagnetic analysis of a three-dimensional inhomogeneous radiator/scatterer in free-space. Such analysis can be carried out by combining the finite element method (FEM) with the method of moments (MoM), which yields finite element-boundary integral (FE-BI) formulations. A general framework is presented, within which stationary FE-BI formulations can be established (variational boundary-value problems), which relate to equivalent, underlying variational principles (stationary functionals). The formulations are shown to be accurate, robust and computationally efficient. They avoid the problem of interior resonances without resorting to the combined field integral equation and they result in symmetric system matrices, which preserve reciprocity explicitly. Thus, the stationary FE-BI framework combines the FEM and MoM on the continuous level, as opposed to the usual approach of hybridization after discretization, which generally leads to asymmetric matrices. The stationary FE-BI framework allows one to solve either for the electric and magnetic fields on the volume of the problem domain, or for one volume and one exterior surface field quantity, with only marginal differences in computational cost. The volume-surface formulations have the same storage requirements as previous FE-BI formulations and can be more efficiently solved. The volume-volume formulations provide simultaneous solutions of the electric and magnetic fields, which could for instance be used to construct error estimators directly based on Maxwell's equations.