微波通信电路中传输线电磁特性与过渡结构夹角关系

微波通信电路中会广泛应用共面波导（CPW）-共面波导以及共面波导-微带（MS）过渡结构。实际应用时,为了布线的方便,通过过孔连接的2段传输线并非始终处于直线上,而可能是任意夹角。仿真分析了经由过孔连接的2段传输线在不同夹角情况下的传播特性。仿真结果表明过渡结构的散射参数受两线夹角影响显著,总体而言,2种过渡结构的|S11|随夹角增大而增大,而|S21|则随夹角增大而减小。散射参数的变化趋势在夹角大于和小于90°时存在差异,在夹角为180°时更明显。此外,还比较并分析了CPW-CPW和CPW-MS结构传播特性的区别。     

Broadband Resonant-Type Metamaterial Transmission Lines

In this letter, it is shown that, contrary to previous assumptions, the broadband characteristics of metamaterial transmission lines are not exclusive of the so called CL loaded composite right/left handed (CRLH) structures. In the balance condition, the typical frequency gap between the left handed (LH) and right handed (RH) transmission bands of these CRLH lines collapses, the characteristic impedance varies smoothly in the vicinity of the transition frequency, and broadband response results. However, through an appropriate design, similar behavior can be obtained in resonant type metamaterial transmission lines, namely transmission lines loaded with complementary split rings resonators. A detailed analysis of the structures, based on the equivalent circuit model is provided, and implications of balancing are pointed out. In this letter, it is clearly demonstrated that broadband balanced CRLH lines can also be implemented by means of the resonant type approach     

Broad-band microstrip-to-CPW transition via frequency-dependent electromagnetic coupling

An improved broad-band microstrip-to-coplanar-waveguide (CPW) transition is developed on a basis of the frequency-dependence characteristic of an electromagnetic surface-to-surface coupling. A self-calibrated method of moments is extended to model this unbounded two-port discontinuity with the two dissimilar microstrip/CPW feeding lines. Numerical results are provided to demonstrate its frequency response of transmission under varied strip/slot dimensions and further exhibit its attractive ultra-broad-band transmission with low radiation loss. Next, the back-to-back transition circuits with the two different lengths are fabricated and measured to deembed in experiment the S-parameters of two single-transition structures. Predicted and measured results show good agreement with the return loss less than -10dB over the frequency of 3.2-11.2 GHz.     

Analysis and design of novel structures of artificial transmissionlines for MMIC/MHMIC technology

In this paper, some new types of artificial transmission lines, compatible with monolithic-microwave integrated-circuit/miniature hybrid-microwave integrated-circuit technology are presented. In the new designs, short subsections of different lines are connected together to achieve the needed performance of various transmission-line functions such as impedance transformation, power coupling, etc. Theoretical calculations are given and some typical design data are provided, including models of extremely low impedance lines, which are very practical in the design of microwave power amplifiers and oscillators using heterojunction bipolar transistors or high electron-mobility transistors. Calculation results are validated by simulations and experiments. The proposed structures are very flexible and can easily provide transmission lines with widely varying characteristics     

Vertical microstrip transition for multilayer microwave circuits with decoupled passive and active layers

A novel broadband (including dc) microstrip-to-microstrip vertical transition for multilayer microwave circuits is proposed. This transition solves the problem of the discontinuity typically appearing in via hole transitions between two microstrip transmission lines in different layers. An analogy existing between this transition and a rectangular coaxial line is discussed. A parametric study alongside with the experimental results of the transition are presented. Reduction of local oscillator to radio frequency leakage in a mixer with this transition is demonstrated.     

Process development in metal/BCB multilayer interconnections of MMCM with embedded chip in Si substrate

A vertical interlayer connection via (VILCV) fabrication process is presented. This process is used for the interconnection of multilayer benzocyclobutene (BCB) based microwave multichip modules (MMCM). The excellent planarity of BCB allows VILCV to be formed using gold electroplating or stud bumps prior to BCB application. And mechanical polishing (MP) planarization is adopted to expose the VILCV, enabling interconnection between different layers. Subsequently upper interconnection is patterned. Metal/BCB multilayer structure can be made by repeating above steps. This approach eliminates the need for laser drilling and plasma etching. Both four terminal Kelvin structures and via chains are fabricated as test vehicles. Finally, a transition of transmission lines in different layers and a packaged MMIC embedded in Si substrate are presented and measured in high frequency range up to 20 GHz. The results show there is only minimal performance degradation.     

基片集成波导和微带转换器的理论与实验研究

基片集成波导(SIW)技术中非常重要的问题之一是该类波导与其它形式传输线的过渡问题.最近已有文章探讨了SIW与微带线过渡的一种锥形结构,在本文中对此类结构进行了全面的拓展,分析了直接过渡、凸型过渡和凹型过渡几种情况,并实验验证了C波段的微带SIW转换器.实验结果表明,在4.1～5.5GHz的频段内,驻波比小于1.2,插损优于0.5dB.     

Fractal Geometries of Complementary Split-Ring Resonators

Complementary split-ring resonators (CSRRs) are typically used as negative-permittivity particles in microstrip left-handed structures. In this paper, novel CSRRs that use a square Sierpinski fractal curve are proposed and studied in detail. It is shown that the application of fractal geometries results in significant miniaturization of the metamaterial unit cell in comparison with conventional and equivalent meander structures. Multiple fractal CSRRs are also analyzed. The influence of different geometrical parameters and the order of the fractal curve on the performances are investigated, as well as the efficiency of excitation of the particles. When used in the design of left-handed transmission lines, fractal complementary split rings improve frequency selectivity in the upper transition band when compared to other nonfractal topologies.     

Propagation and coupling characteristics of microstrip lines withlaminated ground plane

In this paper, we analyze the effect of laminated ground plane on the propagation and coupling characteristics of microstrip lines. Each lamina is modeled as an anisotropic layer, and transition matrix is used to relate the tangential field components in different laminae. An integral equation is formulated in the spectral domain, and the Galerkin's method is applied to solve the integral equation for the phase and the attenuation constants of several microstrip line structures. The effects of substrate dielectric are also studied. The attenuation constant variation thus obtained will be useful in circuit board design and in studying signal transmission in lamina environment     

Bandpass Filters Using Strip Line Techniques

Strip lines provide a convenient transmission medium for the realization of microwave filters. Since bandpass filters designed in waveguide and coaxial lines would be large at ultra-high frequencies, strip lines afford a practical means of realizing filters which are simply fabricated, are readily reproduced, and, in most cases, represent an appreciable savings in size and weight. Of the different types of strip transmission lines currently in use, the so-called "sandwich" structure has been employed at Melpar for two reasons: (1) very broad-band coax-to-strip-line transitions are easily realize; and (2) the electromagnetic field is essentially confined between the two ground planes, thus reducing problems in packaging.     

Micromachined W-band filters

Results are presented for high performance planar W-band filters based on silicon micromachining techniques common in microsensor fabrication. Two types of micromachined planar transmission lines are studied: microshield line and shielded membrane microstrip (SMM) line. In both of these structures, the conducting lines are suspended on thin dielectric membranes. These transmission lines are essentially “floating” in air, possess negligible levels of dielectric loss, and do not suffer from the parasitic effects of radiation and dispersion. A 90 GHz low pass filter and several 95 GHz bandpass filters are tested and display excellent performance which cannot be achieved with traditional substrate supported circuits in CPW or microstrip configurations. A full-wave finite-difference time-domain (FDTD) technique verifies the measured performance of the W-band circuits and provides a basis for comparison between the performances of membrane supported circuits and equivalent substrate supported circuits     

Direct measurement of crosstalk between integrated differentialcircuits

Silicon integrated-circuit test structures have been fabricated that allow direct measurement of crosstalk between differential transmission lines and between single-ended transmission lines in the presence of metal ground plane. The differential test structures are characterized with mixed-mode scattering parameters (common mode, differential mode, and mode conversion), as measured with the pure-mode vector network analyzer. Comparisons with simulation show good agreement for differential-mode crosstalk, and the dependence of crosstalk on transmission-line separation is presented. Difficulties in simulating crosstalk fur even simple structures illustrate the utility of direct measurement of crosstalk     

Multipartite Secret Sharing by Bivariate Interpolation

Given a set of participants that is partitioned into distinct compartments, a multipartite access structure is an access structure that does not distinguish between participants belonging to the same compartment. We examine here three types of such access structures: two that were studied before, compartmented access structures and hierarchical threshold access structures, and a new type of compartmented access structures that we present herein. We design ideal perfect secret sharing schemes for these types of access structures that are based on bivariate interpolation. The secret sharing schemes for the two types of compartmented access structures are based on bivariate Lagrange interpolation with data on parallel lines. The secret sharing scheme for the hierarchical threshold access structures is based on bivariate Lagrange interpolation with data on lines in general position. The main novelty of this paper is the introduction of bivariate Lagrange interpolation and its potential power in designing schemes for multipartite settings, as different compartments may be associated with different lines or curves in the plane. In particular, we show that the introduction of a second dimension may create the same hierarchical effect as polynomial derivatives and Birkhoff interpolation were shown to do in Tassa (J. Cryptol. 20:237–264, 2007). A preliminary version of this paper appeared in The Proceedings of ICALP 2006.     

Analysis of shielded striplines and finlines with finitemetallization thickness containing magnetized ferrites

The applicability of the spectral domain approach is extended to analyze various types of shielded planar transmission lines, taking the anisotropy of the magnetized ferrites and the finite metallization thickness into consideration. The numerical computations include the propagation characteristics of finlines and striplines and the metallization thickness effect in these lines. Numerical data of simpler structures are compared with the available exact solution as well as with published data     

IV–VI Compound heterostructures grown by molecular beam epitaxy

Structural and optical characterization of some IV–VI superlattices (SL) and multi-quantum wells (MQW) grown by molecular beam epitaxy (MBE) on BaF₂ (111) substrates are shown. Three different types of systems were investigated, namely, PbTe/PbSnTe, PbTe/SnTe and PbTe/PbEuTe. High-resolution X-ray diffraction analysis was performed to determine the strain in the structures. The analysis revealed sharp interfaces and good thickness control. The transition energies between the confined levels in the wells were obtained from the absorption steps observed in infrared transmission measurements. Preliminary results on PbTe/Si heterojunction grown by MBE are also presented.     

Transmission-Line Properties of a Round Wire in a Polygon Shield

A family of transmission lines is based on a round wire in a cylindrical shield of polygon cross-section. There is presented a simple formula which gives a smooth transition between the extremes of a small wire and a wire near contact. The same formula is adapted for different shapes by entry of different constants depending on the number of shield planes and the degree of symmetry. The formula is reversible for synthesis or analysis by explicit expression of either shape ratio or wave resistance in terms of the other. For comparison in the transition region, there is computed for each shape a close approximation by the method of images.     

A method for determining the characteristic impedance of transmission lines embedded in transitions

This paper presents a method for determining the characteristic impedance (Z_L) of transmission lines embedded in reciprocal transitions. This method is based in two properties: (1) a reliable method for calculating the propagation constant (γ) of reflecting lines, and (2) the calculation of the S₁₁ parameter of each transition employed for this kind of transmission lines. For calculating the characteristic impedance of these lines, the proposed method uses measurements of two transmission lines with different lengths.     

Compact low-loss monolithic CPW filters using air-gap overlaystructures

In this letter, two types of compact low-loss monolithic coplanar waveguide (CPW) filters using air-gap overlay structures are presented. Vertical stacking in overlay structures offers size reduction. Furthermore, air-gap overlay structures do not require additional dielectric process and are free from dielectric losses. An X-band bandpass filter using air-gap overlaid artificial transmission lines showed 67% size reduction. A stepped-impedance low-pass filter using highly separated metal-air-metal (MAM) capacitors as low-impedance lines achieved not only size but also loss reduction. Small size, low loss, and simple process steps make the air-gap overlay structures very promising for monolithic CPW passive devices such as filters     

New multilayer planar transmission lines for microwave andmillimeter-wave integrated circuits

New types of planar transmission lines employing multilayer structures are proposed for possible applications in microwave and millimeter-wave integrated circuits. Detailed investigations are presented through numerical results calculated using the spectral domain technique. The newly proposed transmission lines have many attractive features such as a large impedance range, flexibility and ability to realize complicated, densely packed integrated circuits, as well as miniaturization through the use of thin dielectric layers. Additionally, they possess all of the inherent advantages of the CPW and microstrip line. Their use in microwave circuits is exemplified through a low-pass filter realized using the new slot-coplanar lines with less than 0.5-dB insertion loss and better than 20-dB return loss. The filter's measured and calculated performances also agree well     

An Investigation of Printed Franklin Antennas at X-Band Using Artificial (Metamaterial) Phase-Shifting Lines

Non-radiating artificial phase-shifting lines are constructed using conventional positive-refractive-index (PRI) transmission lines (TL) and the recently developed negative-refractive-index (NRI) transmission lines. The two types of fully printed artificial lines are used to implement microstrip Franklin antennas. The aim is to provide co-phase excitation to an array of half-wavelength dipoles, which generate a broadside beam at the design frequency. The proposed antenna structures not only retain the benefits of previously published designs but also feature a smaller footprint in the transverse direction. Between the two proposed antenna configurations, the PRI-TL based design allows broadside radiation with minimal beam squinting, while the NRI-TL based design provides a frequency steerable beam. A 14-element antenna array for each configuration is characterized using an intuitive TL model, and the study is experimentally verified at 12 GHz. The measured radiation patterns, directivity, gain, and beam-scanning capability are presented.