Multilayer Stripline Research Articles

Stripline Multilayer Devices Based on Complementary Split Ring Resonators.

A new analytic design for multilayer stripline devices in planar circuit technology is presented. The Complementary Split Ring Resonator (CSRR) is used as a sub-wavelength resonant particle, which provides high-Q resonances in a compact size. The electromagnetic field distribution achieved along the stripline enables enhanced excitation of the resonators. An optimal solution for multilayer power dividers is presented, in a configuration in which each output is obtained in different layers and also in a different layer than the input line. The solution is expanded to design different devices, such as diplexers, resonators, and multi-frequency resonators, leading to vertical filters. As the resonances are achieved by stacking resonators, the effective circuit footprint is very compact. The proposed devices can be implemented in a volumetric chip fashion, allowing integration with planar transmission line circuits and flexible output connection placement. A complete analysis of the different devices is proposed, extracting and verifying their equivalent circuit models.

Using N-Norms for Analyzing Symmetric Protective Electrical Circuits with Triple Modal Reservation

The redundancy of functional blocks and critical assemblies in radio-electronic equipment is among the most widely used techniques for increasing reliability. Complex redundant systems raise the problem of electromagnetic compatibility (EMC). Ignoring EMC requirements can lead to partial or complete REE failures. In this paper, the authors analyze a noise-protective electrical circuit with triple modal reservation (a promising type of cold redundancy). A multilayer stripline is investigated, the conductors of which are symmetrically arranged relative to two planes. On account of the strong electromagnetic coupling, this protective circuit can decompose dangerous ultra-wideband (UWB) interference received at the input of the primary or redundant circuits into unipolar pulses of lower amplitude. Using this approach, due to the symmetry of the conductors, equal decomposition efficiency could be achieved. However, the effect of UWB interference at the input of one of the conductors produces bipolar pulses at the output of the other conductors. In this paper, the authors evaluate the dangers of unipolar and bipolar decomposed pulses and use modal analysis to mathematically determine the polarities and amplitudes of the decomposed pulses at all output nodes for a pseudo-matched structure. By using the quasistatic approach with and without losses, the time responses to a trapezoidal pulse with a total duration of 60 ps, which simulates UWB interference, are obtained. To confirm the results of modal analysis and quasistatic simulation, an experimental study is performed. Using a stroboscopic oscilloscope DSA 8300, the authors obtained a transient response to a step excitation. Then, taking the derivative, the response to a trapezoidal pulse with a total duration of 140 ps was obtained. To analyze the criticality of the decomposed pulses, N-norms are used. In the general case, it is shown that the UWB interference is decomposed into four pulses of lower amplitude. At the same time, the value of each N-norm indicates its significant attenuation. For example, the amplitude of the UWB pulse acting on the input of the reserved conductor decreases by 10.31–8.93 times. Such results numerically demonstrate the high efficiency of the suggested approach when it comes to protecting equipment against UWB interference. It is also shown that the probability of dielectric breakdown and damage to electronic components in redundant circuits is lower than in a primary circuit. This is due to the fact that the value of N3 in the redundant circuit is 2.38 times less than in the primary circuit. However, the results demonstrate that arcing is highly probable both in primary and redundant circuits. Finally, aspects of symmetry/asymmetry in the problem under investigation are emphasized.

Beam steerable subarray with small footprint for use as building block in wall‐mounted indoor wireless infrastructure

A dedicated antenna topology targeting wall-mounted beam-steered mass-producable wireless indoor applications in the microwave band is presented. Four linearly polarised E-shaped microstrip patches are fed by a novel Butler matrix in a 2 × 2 array configuration, realising a very simple two-dimensional beam steering. To isolate the beam forming network (BFN) from the patches and the wall, a multilayer stripline technology was used. The proposed passive BFN consists of stripline couplers without crossings or physically separate phase shifters, leading to a BFN fitting within the same footprint as the array itself. The overall size of the Butler matrix is only 0.54 λ 0 × 0.54 λ 0 × 0.06 λ 0. A prototype at 6 GHz has been realised and measured, proving the validity of the concept.

An efficient algorithm to calculate relative permittivity from multi-layered stripline based measurements at microwave frequencies

In recent years, multi-layer stripline or microstrip line based dielectric measurement has drawn the attention of many researchers. These methods are particularly attractive as they can readily be used for the dielectric measurement of non-metal clad material. Measurement setups developed using the multi-layer approach have the added advantage that they need very little sample preparation. However, the extraction of dielectric properties in these experimental setups is complex due to the multi-layer nature of the problem. At present, this is usually done using brute-force approaches, which take long computational times and large memory. This paper presents an efficient technique based on the Newton Raphson algorithm to address this. The algorithm developed is coded in Matlab and the results show a significant improvement over the brute-force method.

Design of a 4-Way Power Divider Using the Multi-Layered Stripline and Defected Ground Structure

본 논문에서는 적층 스트립라인 전송선로 구조와 공통 결함접지구조를 이용한 4-way 전력분배기의 설계에 대하여 기술한다. 스트립라인 전송선로에서 전자기파의 전송모드는 순수한 TEM 모드여서 quasi-TEM 모드를 사용하는 마이크로스트립 전송선로보다 손실과 전자기파의 누설이 더 적다. 따라서 스트립라인 선로구조는 적층구조의 무선통신용 부품 설계에서 마이크로스트립보다 더 유리하다. 본 연구에서는 적층된 스트립라인의 공통 접지면에 결함접지구조를 삽입하고, 인접하는 양쪽 스트립라인 전송선로에 결함접지구조의 장점을 결합시켜 전력분배기를 설계한다. 적층 스트립라인 구조가 적층 이전에 비하여 이미 자체적으로 소형화된 상태이지만, 여기에 공통 결함접지구조를 삽입하므로 회로는 더욱 소형화되어 표준형 구조를 갖는 평면형 회로의 약 1/3에 불과하다. 크기가 줄어도 회로의 성능은 동일하게 유지된다. 측정된 4-way 전력분배기의 전력분배비는 -6.27~-6.5dB이고, 위상차는 1.01°~2.14°에 불과하며 예측 결과와 매우 유사하다.

Temperature‐Compensated Bandpass Filters in Low Temperature Co‐Fired Ceramic

For low temperature co‐fired ceramic (LTCC) modules targeting radio frequency applications, a near 0 ppm/°C temperature coefficient of resonant frequency (τf) ensures temperature stability of embedded filters. The base dielectrics of most commercial LTCC systems have a τf in the range −50 to −80 ppm/°C. By integrating co‐fireable compensating dielectrics with an opposite τf to that of the host dielectric, we demonstrated multilayer stripline (SL) bandpass filters with a τf approaching 0 ppm/°C using DuPont 951 LTCC. The effective dielectric constant of the SL in multilayer LTCC with dissimilar layered dielectrics was calculated using a variational method with transmission‐line technique.

A compact hairpin bandpass filter using multilayer stripline folded quarter‐wavelength resonators

AbstractThis article presents a compact hairpin bandpass filter using multilayer stripline folded quarter‐wavelength resonators in a low‐temperature cofired ceramic substrate.Using the new structure designs accomplish the vertical coupling in multilayer system, the size of the proposed filter can be reduced about 50% compared to an equivalent single‐layer hairpin resonator filter. As an example, an L‐band filter centered at 1.10 GHz with a fractional bandwith of 13.5% is designed, fabricated, and measured. The measured results of the fabricated filter agree very well with the electromagnetic simulations. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2627–2629, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27139

Design of Embedded and Miniaturized Multilayer LTCC Hairpin Bandpass Filters

This paper presents a new multilayered stripline hairpin bandpass filter using a broadside-coupled hairpin resonator in a low-temperature co-fired ceramic(LTCC) substrate. By using the new structure designs accomplish the vertical coupling in multilayer system, the size of the proposed filter can be reduced about 50% compared to an equivalent single-layer hairpin resonator filter. As an example, an L-band filter centered at 1.10 GHz with a fractional bandwith of 13.5% is designed, fabricated, and measured. The measured results of the fabricated filters agree very well with the electromagnetic simulations.

Design of a Beam Switching/Steering Butler Matrix for Phased Array System

A compact broadband 8-way Butler matrix integrated with tunable phase shifters is proposed to provide full beam switching/steering capability. The newly designed multilayer stripline Butler matrix exhibits an average insertion loss of 1.1 dB with amplitude variation less than ±2.2 dB and an average phase imbalance of less than 20.7° from 1.6 GHz to 2.8 GHz. The circuit size is only 160 × 100 mm2, which corresponds to an 85% size reduction compared with a comparable conventional microstrip 8-way Butler matrix. The stripline tunable phase shifter is designed based on the asymmetric reflection-type configuration, where a Chebyshev matching network is utilized to convert the port impedance from 50 ? to 25 ? so that a phase tuning range in excess of 120° can be obtained from 1.6 GHz to 2.8 GHz. To demonstrate the beam switching/steering functionality, the proposed tunable Butler matrix is applied to a 1 × 8 antenna array system. The measured radiation patterns show that the beam can be fully steered within a spatial range of 108°.

The Stochastic Gabor Function Enhances Bandwidth In Finite-Difference-Time Domain $S$-Parameter Estimation

This paper introduces the stochastic Gabor function, an excitation waveform that can be used for finite-difference time-domain S-parameter estimation. The stochastic Gabor function is a Gaussian function modulated by uniformly distributed noise; it has wide frequency spectrum representation regardless of the stimuli pulse length. The stochastic Gabor function was studied in the time-frequency domain and was compared to Gaussian and Gabor stimuli functions with the same length. As shown by frequency concentration measurements, the stochastic Gabor function is least compact in the sample frequency phase plane. Numerical results obtained by using a multilayer stripline indicate that the stochastic Gabor function provides convergence and stability similar to those provided by the Gabor and Gaussian functions, but produces a much wider frequency band response when used as a pointwise hard voltage source stimulus

Quasi-static solutions of multilayer elliptical, cylindrical coplanar striplines and multilayer coplanar striplines with finite dielectric dimensions - asymmetrical case

In this paper, fast, accurate, and simple analytic closed-form expressions are presented in order to calculate the quasi-TEM parameters of multilayer elliptical coplanar stripline (CPS), multilayer cylindrical CPS, and multilayer CPS, with finite dielectric dimensions by using conformal mapping techniques. The obtained computer-aided-design-oriented expressions are quite accurate and easy to apply in designing microwave integrated circuits and antenna applications. The results have also been compared with the ones of another conformal mapping method available in the literature and also confirmed analytically.

Novel Analytical Representations of the Continuous-Spectrum Current in Multilayer Stripline Structures

We consider a multilayer stripline structure excited by a delta-gap source and we study the continuous-spectrum current, which may be responsible of several spurious transmission effects such as interference with the quasi-TEM mode, undesired radiative effects, and crosstalk. In particular, a uniform asymptotic analysis of such continuous spectrum is presented, based on two alternative closed-form representations. Both representations are accurate also very close to the source and are valid inside a wide frequency range starting from DC. One formulation has a direct implementation, since it needs only knowledge of the spectral Green's function of the background structure. The other formulation requires knowledge of the exact complex (leaky) poles of the stripline Green's function and of their residues, but provides more physical insight since it gives quantitative information on the role of leaky waves in the continuous-spectrum representation in the entire considered frequency range. Numerical results which validate the accuracy and efficiency of the proposed approaches are provided at different frequencies for covered-microstrip structures with different strip widths.

An excitation theory for bound modes, leaky modes, and residual‐wave currents on stripline structures

The nature of the current on a general multilayered printed‐circuit stripline structure excited by a delta‐gap source is investigated. The current is obtained through the construction of a semianalytical three‐dimensional (3‐D) Green's function, which accounts for the presence of the infinite conducting strip and the layered background structure. The 3‐D Green's function is obtained by Fourier transforming the delta‐gap source in the longitudinal (z) direction, which effectively resolves the 3‐D problem of a delta‐gap source into a superposition of 2‐D problems, each of which is infinite in the z direction. The analysis allows for a convenient decomposition of the strip current into a sum of constituent parts. In particular, the strip current is first resolved into a set of bound‐mode current waves and a continuous‐spectrum current. The continuous‐spectrum current is then represented as a set of physical leaky‐mode currents in addition to a set of “residual‐wave” currents, which arise from the steepest‐descent integration paths. An asymptotic analysis reveals that the residual‐wave currents decay algebraically as z−3/2. Far away from the source, the residual‐wave currents dominate the continuous‐spectrum strip current. Results are shown for a specific type of stripline structure, but the analysis and conclusions are valid for arbitrary multilayer stripline structures.

High combining-efficiency X-band spatial power-combined array using a multilayered packaging architecture

The design of a high combining-efficiency spatial power-combined array is described in this paper. A multilayered stacked stripline architecture enables a compact stable design. An array incorporating antenna active impedance and proper amplifier matching is measured with a combining efficiency of 87%, radiating 6.8 W of an available 7.8 W into the ideal uniformly illuminated array directivity at 10.1 GHz.

Artificial neural network models for the double-vias in multilayer stripline circuits

Multi-vias is a kind of interconnection largely existing in the multi-chip module (MCM) packages for high-speed digital circuits. In this paper, a multilayer perceptron neural network (MLPNN) is used to model the double-vias in multilayer stripline circuits. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. One type of the designs of experiments, the central composite technique, is used to allow for a minimum number of FDTD simulations that is needed to be performed.

Excitation of leaky modes on multilayer stripline structures

A quasi-analytical method for calculating the excitation of leaky modes on multilayer stripline structures by a finite source is presented in this paper. Simple sources such as an infinitesimal dipole near the conducting strip or a delta-gap feed on the conducting strip of the transmission line are considered. The method uses a numerically constructed Green's function for the source in the presence of the conducting strip, which is calculated from Fourier transform theory in terms of a one-dimensional Green's function for a line source in the presence of the conducting strip. The numerical Green's function involves a one-dimensional integration in the longitudinal wavenumber plane. The residue contributions from the poles of the Green's function define the excitation amplitudes of the leaky and bound modes that exist on the structure. The numerical Green's function is also used to numerically calculate the complete current on the strip excited by the source. The correlation between the leaky-mode current and the complete current is used to define the extent of the physical meaning of the leaky mode. The generalized pencil of functions (GPOF) method is used to study this correlation by resolving the complete current on the strip into exponential waves, which are then compared with the current of the leaky mode. The physical meaning of the leaky modes is also analytically examined by consideration of the branch cuts in the longitudinal wavenumber plane for the numerical Green's function integration. A path consistency is established as a necessary condition for the physical meaning of the leaky mode.

Amplitude uhf humidity meter for solid and powdered materials

An instrument is described for measuring the water content of a material on the basis of a multilayer stripline. A model is proposed for the instrument that agrees well with experiment.

Thermal properties of five-layer infinite plate structures with embedded heat sources

The analytical three-dimensional temperature solution of a five-layer anisotropic plate structure with infinite lateral boundaries and with embedded heat sources has been derived. By incorporating the method of images, this solution can be utilized to obtain the exact solution of a five-layer structure with rectangular lateral boundaries and with embedded heat sources. Consequently, this solution constitutes the most general analytical expression reported so far. The solution is in the form of a double Fourier integration. To carry out the integration effectively, the characteristics of the transformed temperature in the Fourier domain have been studied. Subsequently, an integration algorithm has been developed for the efficient numerical integration of the double Fourier inverse transform for temperature calculation. In comparison with the double Fourier series solution of rectangular structure, the solution reported here is not only much more computationally effective but also more general. Besides thermal problems, the solution also has important applications in electrostatics since the thermostatics share the same equations with electrostatics. Examples of electrostatic problems are multilayer stripline, and microstrip, multilevel interconnection of integrated circuits, and multilayer printed circuit boards.

Generalized interdigital filters made of multilayer striplines

AbstractIn the first part of this paper is presented a relatively simple loss analysis method for many coupled line structures. The corresponding equivalent circuit consists of uncoupled lossy transmission lines whose parameters are determined relatively easily without a complex numerical field analysis by using fringing‐capacitance curves for rectangular strips. In the narrowband case further approximations are possible. The increase of the accuracy is most significant if the couplings between strips are tight.In the second part a realization of the generalized interdigital filter using a multilayer structure consisting of polyphenyleneoxide plates is discussed. The repeatability of the filters is improved with the aid of thin polyethylene films. The shorts are made by the copper coating that also effectively suppresses higher‐order modes. The fine tuning of the filter can be made by tuning screws. The improvement of the design accuracy without tuning elements using a computer simulation is also discussed. Finally, the effects of the losses are studied, connecting the loss analysis presented with ring resonator measurements.

A Lossy Element for EMC Filters

The need and advantages of lossy elements in unconditional EMC filter design are well recognized. This paper describes a lossy device based on the proximity effect using multilayer strip lines. Expressions are derived for the losses in the multilayer strip conductors. Experimental data show good agreement with theoretical expectations when the differences between the theoretical model and actual implementations are taken into account. The formula for an infinite stack provides a theoretical upper limit to the losses as a function of frequency. A modified empirical formula provides a practical design equation. Applications are also discussed.