System-reliability confidence-intervals for complex-systems withestimated component-reliability

A flexible procedure is described and demonstrated to determine approximate confidence intervals for system reliability when there is uncertainty regarding component reliability information. The approach is robust, and applies to many system-design configurations and component time-to-failure distributions, resulting in few restrictions for the use of these confidence intervals. The methods do not require any parametric assumptions for component reliability or time-to-failure, and allows type-I or -II censored data records. The confidence intervals are based on the variance of the component and system reliability estimates and a lognormal distribution assumption for the system reliability estimate. This approach applies to any system design which can be decomposed into series and/or parallel connections between the components. To evaluate the validity of the confidence limits, numerous simulations were performed for two hypothetical systems with different data sample-sizes and confidence levels. The test cases and empirical results demonstrate that this new method for estimating confidence intervals provides good coverage, can be readily applied, requires only minimal computational effort, and applies for a much greater range of design configurations and data types compared to other methods. For many design problems, these confidence intervals are preferable because there is no requirement for an exponential time-to-failure distribution nor are component data limited to binomial data     

On the design of planar microwave components using multilayerstructures

The design of planar microwave components using multilayer configurations with potentially arbitrary numbers of dielectric layers and metallization planes is described. Analysis and design are based on a combination of a spectral domain immittance matrix approach and standard CAD methods. To verify the design procedure, three examples-microstrip-slot-line-microstrip transition, a stripline band-pass filter, and a microstrip coupler with lines on different sides of a common ground plane-are investigated theoretically and experimentally     

Asymmetric, multi-conductor low-coupling structures for high-speed,high-density digital interconnects

Small inter-line spacings and high switching speeds emphasize the problems of crosstalk and coupling distortion in high-speed, high-density digital interconnects. The use of substrate compensation allows the design of structures in which crosstalk and coupling can be essentially eliminated, even for inter-line spacings of less than one center conductor width. Characteristics of this novel method are presented for both symmetric and asymmetric multiline geometries. Pulse distortion and crosstalk on a four-line, symmetric structure are analyzed, showing how crosstalk and coupling distortion are reduced by substrate compensation. Pulse distortion on symmetric coupled lines is studied, showing that it is possible to choose a substrate combination which significantly reduces coupling and crosstalk for a wide range of conductor configurations     

Acoustic-surface-wave processor for hyperbolic f.m. signals

The design of an acoustic-surface-wave transversal filter for generation and processing of hyperbolic f.m. signals is described. The synthesis procedure consists in linear-modulating the spatial period of an interdigital array of tapping transducers on a piezoelectric substrate. Two interdigital configurations have been designed, the first operating at the fundamental frequency, the other at the overtone mode which allows the use of the minimum number of transducers.     

Design of Coupled Microstrip Lines (Letters)

An accurate and direct method for designing coupled microstrip lines for any substrate is given once the design curves for any other substrate are known.     

Substrate-Integrated-Waveguide Circulators Suitable for Millimeter-Wave Integration

Over the years, many millimeter-wave circulator techniques have been presented, such as nonradiative dielectric and fin-line circulators. Although excellent results have been demonstrated in the literature, their proliferation in commercial devices has been hindered by complex assembly cost. This paper presents a study of substrate-integrated millimeter-wave degree-2 circulators. Although the substrate integrated-circuits technique may be applied to virtually any planar transmission medium, the one adopted in this paper is the substrate integrated waveguide (SIW). Two design configurations are possible: a planar one that is suitable for thin substrate materials and a turnstile one for thicker substrate materials. The turnstile circulator is ideal for systems where the conductor losses associated with the thin SIW cannot be tolerated. The design methodology adopted in this paper is to characterize the complex gyrator circuit as a preamble to design. This is done via a commercial finite-element package.     

Transmission line modeling of substrate resistances and CMOS latchup

Substrate resistance in epitaxial-CMOS is more appropriately viewed as a lossy transmission line than as a lumped resistor or as a resistance ladder network. Lossy transmission lines can be used to model a variety of substrate resistance configurations, including the resistance necessary to quantitatively predict turn on of the lateral parasitic bipolar during latchup. Voltage and current distributions predicted by the transmission line model are in excellent agreement with two-dimensional numerical simulations. Parameter values for the model are easily related to vertical doping profiles and to a wide variety of parasitic p-n-p-n layouts. For CMOS design the lateral bipolar's bypass resistor, commonly found in lumped element models of the parasitic p-n-p-n, is replaced by a transfer resistance derived from the transmission line model. Butted substrate contacts are shown to provide a worst-case design situation.     

A model-oriented approach to measure rain-induced cross-polarization

In this paper a new model oriented approach to measuring rain-induced cross-polarization is outlined: it aims at characterising the physical properties of the depolarising medium rather than at directly measuring the channel depolarization, which is the variable of direct interest for system design. This approach, which allows subsequent determination of depolarization has the advantages of allowing a better understanding of the propagation mechanism, thus yielding information applicable to any system configuration and establishing common procedure to compare cross-polarization data obtained in different circumstances. Different experimental configurations are reviewed together with their ability to identify and assess various possible models for the depolarizing medium.     

Design of probe-fed stacked patches

In this paper, a design strategy to achieve bandwidths in excess of 25% for probe-fed stacked patches is presented. The choice of appropriate dielectric materials for such bandwidths is given and the role of each antenna parameter in controlling the impedance behavior is provided. It has been found that the selection of the substrate below the lower patch plays a major role in producing broad-band responses. A simple design procedure is outlined and this technique is verified experimentally. The findings presented here can be applied to all types of probe-fed stacked patches as well as edge-fed and cavity-backed configurations     

Printed dipoles electromagnetically coupled to coplanar waveguide for linear or circular polarisation

Two configurations are proposed for feeding printed dipoles with coplanar waveguide transmission lines. The coplanar waveguide feed is printed on a ground plane sandwiched between a high-permittivity substrate and a low-permittivity substrate which supports the antenna. Both linear and circular polarisation can be achieved. Measured results are presented.     

A general theory on the graphical representation ofantenna-radiation fields

A general theory for graphical representation of antenna radiated fields is developed. The application of the method to the special case of a transverse electromagnetic-mode-excited biconical antenna is investigated in detail. Electric field lines in the r-ϑ plane of a spherical coordinate system are presented in a manner such that the same electric flux is always carried between two neighboring field lines. Thus, their mutual distance is a criterion for the strength of the local electric field. The differential equations which govern the displacement of a field point are derived and solved. The time-dependent evolution of a field-line pattern is examined in detail. The new theory for graphical field representation permits, in an elegant manner, the analysis of the transmission and receiving mechanism of arbitrary antenna configurations. Thus, it is suggested that an iterative graphical synthesis procedure could, in the future, be applied to the computer-aided design modeling of antenna shapes     

Characterization of microstrip lines near a substrate edge anddesign formulas of edge-compensated microstrip lines [MMICs]

The proximity effects of microstrip lines near a substrate's edge present a problem for effectively designing high-packing-density MMICs (monolithic microwave integrated circuits). Proximity effects of this type are analyzed using the rectangular boundary division method. It is assumed that the cross-sectional dimensions of transmission lines in the MMICs are small compared with the wavelengths to allow the use of the quasi-TEM-wave approximation. Then, the concept of edge-compensated microstrip lines to keep the characteristic impedance constant near a substrate edge is introduced to circumvent the proximity effects and to expand the interconnection flexibility of microstrip lines on MMIC substrates. The practical design parameters of edge-compensated 50-Ω microstrip lines are given in the form of numerical data and simple polynomials for CASD (computer-aided design) work with a curve-fitting procedure. Results of capacitance measurements are compared with this theory with errors of about 1% resulting     

An improved procedure for the design of periodic-permanent-magnet assemblies for traveling-wave tubes

A detailed analysis of the magnetic-field configurations in periodic focusing structures and new knowledge related to the design of permanent magnets which are to be used in the presence of fields of other magnets have led to the development of a new procedure for the design of periodic-permanent-magnet (ppm) focusing structures for traveling-wave tubes. With this new procedure, the ppm focusing structures can be designed very quickly, and the parameters of the structures produced will approximate the design predictions very closely. This paper describes the derivation and use of a set of design curves which have been used in the design of ppm focusing structures by the RCA Microwave Tube Operations Department for six years. It has been found that the peak axial fields of the structures produced on the basis of these design data are within five percent of the predicted values. Frequently, agreement between actual and predicted values within one percent has been observed. The design procedure requires only a few minutes time, and is applicable to any magnet material whose demagnetization curve is known. A section on the design of the soft-magnetic pole pieces ("shims") is also included.     

Millimeter-wave Ka-band H-plane diplexers and multiplexers

Millimeter-wave H-plane diplexers/multiplexers are designed using modified H-plane waveguide T-junctions and modified inductive window bandpass filters. Modeling of the diplexers/multiplexers are performed using the full-wave mode-matching method to obtain the generalized scattering matrices of the building blocks and by the cascading procedure to provide the overall frequency response. A complete systematic optimization procedure leads to the desired diplexer/multiplexer design. The validity of employing the modified H-plane T-junctions in the diplexer/multiplexer configurations are demonstrated by the design examples. A millimeter-wave Ka upper band diplexer based on the simulated results was built and tested. Without any tuning, excellent experimental results are obtained, which verified the full-wave mode-matching-based precise design     

On the design of a multiplexer with a common junction

Two sets of formulas for scattering parameters are presented for multiplexers having parallel and series configurations with a common junction. A new general design approach is developed for multiplexers having any response types and any number of channel filters of arbitrary degree, bandwidth, and interchannel spacing. By using these formulas and computer optimization techniques for all the element values in the channel filters, the design process results in a good match at the common input port over the transmission frequency band. Several examples including a contiguous multiplexer are given to demonstrate the design procedure.This work was supported by Air Force Systems Command under Contract F33615-84-K-1556.     

Design of metal interconnects for stretchable electronic circuits

The trend of microelectronic products in the textile or medical field is toward higher functionality, miniaturization, application of new materials and a necessity for deformable electronic circuits for improving the comfort control. In this work, the design of flexible and stretchable interconnections is presented. These interconnections are done by embedding sinuous electroplated metallic wires in a stretchable substrate material. A silicone material was chosen as substrate because of its low stiffness and high elongation before break. Common metal conductors used in the electronic industry have very limited elastic ranges; therefore a metallization design is crucial to allow stretchability of the conductors going up to 100%.Different configurations were simulated and compared among them and based on these results, a horseshoe like shape was suggested. This design allows a large deformation with the minimum stress concentration. Moreover, the damage in the metal is significantly reduced by applying narrow metallization schemes. In this way, each conductor track has been split in four parallel lines of 15 μm and 15 μm space in order to improve the mechanical performance without limiting the electrical characteristics.     

Elements of cellular mobile radio systems

A major concern in a cellular mobile radio system is the co-channel interference. Therefore, the reduction of co-channel interference becomes a main thrust for the system design engineers. We use the co-channel interference reduction factor as a design criterion and predict the signal-to-interference (S/I) ratios in different system configurations. The handoff mechanism and algorithmic considerations, the traffic capacity and procedure for splitting cells, and the near-end-to-far-end ratio interference and reduction are the elements described.     

Optimum design of thyristor gate—Emitter geometry

This paper describes a new method of studying the influence of the gate-emitter geometrical configuration of thyristors upon their triggering performances. This method allows, for devices of any geometrical complexity, to calculate the emitter bias voltage distribution prior to turn-on and hence to compare the behavior of these devices from a geometrical point of view. The results may be used as guide lines for the optimum design of gate-emitter configurations. As examples, precise design rules are given for standard thyristors and application to amplifying interdigited gate thyristors are outlined.     

Calculation of Characteristic Admittances and Coupling Coefficients for Strip Transmission Lines

An integral equation technique is presented which may be used to efficiently compute the Maxwellian capacitance matrix, i.e., the coefficients of capacitance and inductance, for any system of zero-thickness strip conductors located parallel to and between two ground planes, The TEM characteristic admittances for various operating modes and the coupling coefficients can then be obtained from the elements of this matrix. A single computer program based upon this technique can be used to compute the capacitance matrix for any particular strip line configuration desired and would thus be especially valuable to the design engineer who would like to quickly obtain accurate design curves for a previously unstudied configuration of ship conductors. This procedure gives much more accurate results in but a fraction of the computer time required when the more common finite difference equation approach is used, and it avoids the necessity for a separate mathematical analysis for each new strip line configuration, as would be required when using a conformal mapping technique. Illustrative results are given for several different strip-line configurations.     

Analysis of a new annular multi-slits antenna using wave concept iterative process in cylindrical coordinates

In this paper, a new antenna for satellite applications is proposed. This antenna is designed to operate at any frequency desired. It consists of a circular microstrip patch antenna which incorporates concentric annular slits, and it is printed on a grounded substrate. The details of the proposed antenna design and numerical results are presented and discussed. The wave concept iterative procedure in cylindrical coordinates is used to analyze this new antenna. Using the proposed procedure, less computing time and memory are needed to calculate the electromagnetic parameters of the annular multi-slits antenna.