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Author(s): Xu Sun [1,2]; Zixiu Bai [1]; Kun Lin [1]; Pengpeng Jiao (corresponding author) [1]; HuaPu Lu [2] In the article titled “Optimization Model of Traffic Sensor Layout considering Traffic [...]

In order to improve the accuracy, reliability, and economy of urban traffic information collection, an optimization model of traffic sensor layout is proposed in this paper. Considering the impact of traffic big data, a set of impact factors for traffic sensor layout is established, including system cost, multisource data sharing, data demand, sensor failures, road infrastructure, and sensor type. The impacts of these influential factors are taken into account in the traffic sensor layout optimization problem, which is formulated in the form of multiobjective programming model that includes minimum system cost, maximum truncation flow, minimum path coverage, and an origin-destination (OD) coverage constraint. The model is solved by the tolerant lexicographic method based on a genetic algorithm. A case study shows that the model reflects the influence of multisource data sharing and fault conditions and satisfies the origin-destination coverage constraint to achieve the multiobjective optimization of traffic sensor layout., Author(s): Xu Sun [1,2]; Zixiu Bai [1]; Kun Lin [1]; Pengpeng Jiao (corresponding author) [1]; HuaPu Lu [2] 1. Introduction With the development of Intelligent Transportation Systems, large-scale acquisition of [...]

A facile method to prepare microfiltration membrane was proposed in this study. The method involved the interfacial polymerization of 1,6-hexamethylene diamine and adipoyl chloride to form polyamide (nylon 6,6) on the polyacrylonitrile (PAN) electrospun nanofi-brous (ENF) membranes as the scaffold. The effects of process parameters, such as monomer concentrations, monomer coating sequence, reaction time and number of reaction cycles, on the amount of polyamide that formed were investigated. It was found that polyamide that formed by interfacial polymerization existed not only on the surface but also in the interior of the ENF membranes. A mechanism was proposed to explain the phenomenon. The pore sizes of the formed poly-amide/PAN ENF membranes, ranging from 0.13 to 4.88 pm, can be controlled by the number of reaction cycles. These polyamide/PAN ENF membranes also exhibited enhanced tensile strength. POLYM. ENG. SCI., 54:430-437, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION Filtration by polymeric membranes is an important separation and purification process in various industries. Depending on the sizes of filtered particles, these membranes can be used for reverse osmosis [...]

One of the problems encountered in fluid-assisted injection-molded parts is the gas or water 'fingering' phenomenon, in which gas (water) bubbles penetrate nonuniformly into the core of the parts and form finger-shape branches. Severe fingerings can lead to significant reductions in part stiffness. This study investigated the fingering phenomenon in fluid-assisted injection-molded disk parts. Experiments were carried out on a reciprocating injection-molding machine equipped with gas- and water-injection units. The material used was virgin polypropylene. A disk cavity with two different thicknesses was used for all experiments. The effects of various processing parameters on the fingering were examined. It was found that the melt short shot size and mold temperature were the principal parameters affecting the formation of part fingerings. In addition, the formation mechanism of part fingerings has also been proposed to better understand the formation of part fingerings. It has been shown that the fluid-assisted filling process is an unstable system by nature. Any small perturbation by material viscosity or by temperature gradient can trigger the unbalance of gas (water) penetrations in the parts and result in fingerings. POLYM. ENG. SCI., 49:2257-2263, 2009. [C] 2009 Society of Plastics Engineers, INTRODUCTION Fluid-assisted injection molding technologies, including gas-assisted (1-3) and water-assisted (4-7) injection moldings, have received extensive attention in recent years, because of the light weight of molded parts, relatively lower [...]

An efficient active LC snubber for forward converters is proposed in this paper. The proposed active LC snubber can be used to reset transformer and suppress switching surge. Further, by storing surge energy in the proposed active LC snubber and then releasing it to the flyback auxiliary output, the converter can achieve high efficiency. For a forward converter with active LC snubber, 91.02%, the maximum output efficiency can be obtained. Because of the high performance on surge suppression and energy recovery, experimental results show that the output efficiency of this proposed converter is higher than that of active-clamped-based converters. Furthermore, for a synchronous rectification forward converter with this active LC snubber, the maximum output efficiency can be further raised to 94.72%. Index Terms--Active LC snubber, flyback auxiliary output, synchronous rectification.

A compact and broadband 0.8-77.5-GHz passive distributed drain mixer using standard 0.13-[micro]m CMOS technology is presented in this paper. To extend the operation bandwidth, a uniform distributed topology is utilized for wideband matching. This paper also analyzes the device size and number of stages for the bandwidth of the CMOS distributed drain mixer. To optimize the conversion gain performance of the CMOS drain mixer, a gate bias optimization method is proposed and successfully implemented in the mixer design. This mixer consumes zero dc power and exhibits a measured conversion loss of 5.5 [+ or -] 1 dB from 0.8 to 77.5 GHz with a compact size of 0.67 x 0.58 [mm.sup.2]. The output 1-dB compression point is -8.5 dBm at 20 GHz. To best of our knowledge, this monolithic microwave integrated circuit has the widest operation bandwidth among CMOS wideband mixers to date with good conversion efficiency and zero dc power consumption. Index Terms--CMOS, distributed mixer, drain mixer, millimeter wave (MMW).

A geometry-scalable parasitic deembedding technique for on-wafer S-parameter measurements of silicon MOSFETs is presented. The developed method is observed to be accurate, area efficient, and time saving for evaluating the intrinsic characteristics of silicon-based devices.

An RF electrostatic discharge (ESD) protection for millimeter-wave (MMW) regime applied to a 60-GHz low-noise amplifier (LNA) in mixed-signal and RF purpose 0.13-[micro]m CMOS technology is demonstrated in this paper. The measured results show that this chip achieves a small signal gain of 20.4 dB and a noise figure (NF) of 8.7 dB at 60 GHz with 65-mW dc power consumption. Without ESD protection, the LNA exhibits a gain of 20.2 dB and an NF of 7.2 dB at 60 GHz. This ESD protection using an impedance isolation method to minimize the RF performance degradation sustains 6.5-kV voltage level of the human body model on the diode and 1.5 kV on the core circuit, which is much higher than that without ESD protection ( Index Terms--CMOS integrated circuits (ICs), low-noise amplifiers (LNAs), millimeter-wave (MMW) circuits, RF electrostatic discharge (ESD) protection.

This paper proposes a circuit topology which reduces the chip size of single-pole-double-throw (SPDT) quarter-wavelength bandpass filter-integrated switches (FIS). A 40-GHz mHEMT MMIC SPDT switch has been implemented and demonstrates a measured insertion loss lower than 1 dB and an isolation better than 30 dB. Another 50-GHz pHEMT MMIC SPDT achieves 1.5 dB insertion loss and 22 dB isolation. The low insertion loss and high isolation shows that the circuit performance is improved along with the reduction of the size. The systematic design approach of the reduced-size FIS is described, together with the analysis of the insertion loss and isolation. Index Terms--Filters, reduced-size, single-pole-double-throw (SPDT), switches.

In this study, the effects of annealing conditions on the magnetic characteristics of multilayered perpendicular magnetic tunnel junctions (pMTJ) of the structures SiNx/Pt/[(Co/Pd).sub.10]/MgO/[(Co/Pt).sub.5]/Pt with various MgO barrier thicknesses were explored. We found that both the fixed and free layers exhibit coercivity growth with increasing annealing temperature. Insertion of a 0.4 nm Mg layer under the MgO barrier layer increases the corecivities further. Magnetoresistance measured by the current-in-plane tunneling (CIPT) method reveals that the insertion of Mg layers on both side of the MgO layer can increase the MR ratio by up to 32%. Index Terms--Co/Pd, Co/Pt, MgO, perpendicular magnetic tunnel junction (pMTJ), tunneling magnetoresistance (TMR).

A miniature test structure is described for RF device characterization and process monitoring. The new design has minimized the voltage drop across interconnects and has prevented capacitive coupling to devices.

The stacked-device power-combining technique is a proven method to increase the output power and load impedance of a power amplifier (PA) simultaneously. The series-input configuration is physically realizable for multicell stacked device configuration in monolithic circuits. The series-input and series-output stack configuration is rigorously analyzed and proven to increase both the input impedance and output impedance simultaneously, easing the matching circuit designs in high PAs. The effects of asymmetry of the input feed and amplifier cells due to distributed effects and process variation on the performance of the stack amplifier are discussed. A four-cell HBT amplifier operating at 5-6 GHz is demonstrated to validate the circuit concept. Index Terms--Monolithic microwave integrated circuit (MMIC) power amplifiers (PAs), stacked amplifier.

40-GHz monolithic microwave integrated circuit (MMIC) single-pole--double-throw and multiple-port bandpass filter-integrated switches based on electronically switchable resonators are proposed. The proposed multifunction chip integrates a multiple-port switch with bandpass filter functions in a single chip. The switchable resonators are formed by quarter-wavelength stepped-impedance resonators with passive HEMT loading at one end. By properly allocating the resonant frequencies of the resonators in their on and off modes, a filter-integrated switch can perform a bandpass response with spurious suppression in the on state and achieve wideband isolation in the off state. The technique of using shared resonators is also introduced in the circuit design to reduce the overall circuit size. The results show the proposed circuits successfully integrate a MMIC switch with bandpass filter functions into a single circuit component. Index Terms--Bandpass filter, monolithic microwave integrated circuit (MMIC), multiple port, single-pole double-throw (SPDT), stepped-impedance resonator (SIR), switch.

This paper proposes a method to integrate a single-pole-double-throw (SPDT) switch and a quarter-wavelength bandpass filter. A 1-GHz SPDT hybrid switch and a 60-GHz pseudomorphic HEMT monolithic-microwave integrated-circuit SPDT switch with 30% fractional bandwidth are demonstrated. The 1-GHz SPDT switch achieves 1.5-dB insertion loss and 20-dB isolation at center frequency. For the 60-GHz SPDT switch, the measured insertion loss is lower than 2.5 dB and the isolation is higher than 27 dB. The low insertion loss and high isolation show that no performance is degraded when integrating the filter function. The analysis of the power performance is also described. Using the device dc-IV curves, the power compression point can be predicted. Index Terms--Bandpass filter, monolithic microwave integrated circuit (MMIC), power compression point, single-pole double-throw (SPDT).

The analysis and systematic design procedure for multiconductor coupled-line Marchand baluns are presented in this paper. A simple two-conductor coupled-line model is used to analyze the Marchand balun and simplify the analysis significantly. Two monolithic balanced frequency doublers with miniature Marchand baluns are implemented to verify the design procedure. Both the chips achieve the smallest chip sizes at their operating frequencies with comparable performance. Index Terms--Balun, diode, frequency doubler, Marchand balun, monolithic microwave integrated circuit (MMIC).

A new transmission-line concept, called the field-effect transistor (FET)-integrated coplanar waveguide (CPW), is proposed. This concept treats the passive two-finger FET as CPW and, thus, the scaling rule is more accurate than the previous model, especially in high frequency. The extraction approach of the parameters of the FET-integrated CPW is also included. With this concept, the design procedure of traveling-wave switches can be equivalent to a filter synthesis problem. Based on this design procedure, a single-pole single-throw and a single-pole double-throw traveling-wave switch have been realized and measured using 0.15-[micro]m high-linearity AlGaAs/InGaAs/GaAs pseudomorphic high electron-mobility transistors. Finally, the frequency limitation of the traveling-wave switches is also discussed. The results show the FET-integrated CPW is the most efficient way to overcome the frequency limitations of traveling-wave switches, achieving operation frequency to 135 GHz, the highest frequency reported to date. Index Terms--Coplanar waveguide (CPW), field-effect transistor (FET), traveling-wave switch.

Electrostatic discharge (ESD) protection design for mixed-voltage I/O interfaces has been one of the key challenges of system-on-a-chip (SOC) implementation in nano-scale CMOS processes. The on-chip ESD protection circuit for mixed-voltage I/O interfaces should meet the gate-oxide reliability constraints and prevent the undesired leakage current paths. This paper presents an overview on the design concept and circuit implementations of the ESD protection designs for mixed-voltage I/O interfaces without using the additional thick gate-oxide process. The ESD design constraints in mixed-voltage I/O interfaces, the classification and analysis of ESD protection designs for mixed-voltage I/O interfaces, and the designs of high-voltage-tolerant power-rail ESD clamp circuit are presented and discussed. Index Terms--Electrostatic discharge (ESD), ESD protection design, gate-oxide reliability, high-voltage tolerant, mixed-voltage I/O interfaces, power-rail ESD clamp circuit.

A low insertion-loss single-pole double-throw switch in a standard 0.18-[micro]m complementary metal-oxide semiconductor (CMOS) process was developed for 2.4- and 5.8-GHz wireless local area network applications. In order to increase the [P.sub.1dB], the body-floating circuit topology is implemented. A nonlinear CMOS model to predict the switch power performance is also developed. The series-shunt switch achieves a measured [P.sub.1dB] of 21.3 dBm, an insertion loss of 0.7 dB, and an isolation of 35 dB at 2.4 GHz, while at 5.8 GHz, the switch attains a measured [P.sub.1dB] of 20 dBm, an insertion loss of 1.1 dB, and an isolation of 27 dB. The effective chip size is only 0.03 [mm.sup.2]. The measured data agree with the simulation results well, including the power-handling capability. To our knowledge, this study presents low insertion loss, high isolation, and good power performance with the smallest chip size among the previously reported 2.4- and 5.8-GHz CMOS switches. Index Terms--Body-floating technique, complementary metal-oxide semiconductor (CMOS) switches, nonlinear model, single-pole double-throw (SPDT).

Power bus structure, consisting of two parallel solid power and ground planes separated by an insulator, behaves as a cavity resonator at high frequencies. Noise on the power bus, due to a sudden change in the current drawn by an active component, can appear as an undesired spatial fluctuation in the voltage between power and ground, especially at resonant frequencies of the resultant cavity, which may lead to problems in signal integrity, excessive delays, false switching, and radiated emission. These resonances can be suppressed by introducing high-frequency loss into the structure. This paper investigates a simple method to reduce self-/transfer impedance of power/ground planes for mitigating power/ground bounce in high-speed printed circuit board design by adding a thin layer of magnetic material coating to the inside-facing surfaces of copper power and ground plates to increase their effective high-frequency surface impedance. The increased surface impedance will increase the attenuation constant of the propagating wave inside the cavity that benefits reduction of cavity's quality factor (Q factor). The simulation results obtained from a modified cavity resonator model show that increasing surface impedance can dramatically reduce self- and transfer impedances at board resonant frequencies. Index Terms--Cavity resonator model, ground bounce, magnetic material coating, self-/transfer impedance, simultaneous switching noise (SSN), surface impedance.

A general three-port S-parameter de-embedding method using shield-based test structures for microwave on-wafer characterization is presented in this paper. This method does not require any physical equivalent-circuit assumption for the surrounding parasitics of a device-under-test. We use one open and three thru dummy devices to remove the parasitic components connected to the gate, drain, and source terminals of a MOSFET. By shielding the lossy silicon substrate, the cross-coupling from port to port can be significantly mitigated, and thus, the parasitics of probe pads and interconnects at each port can be separately subtracted. The MOS transistor and its corresponding dummy structures fabricated in a 0.18-[micro]m CMOS process were characterized up to 20 GHz. Compared with the two-port cascade-based de-embedding method, the proposed three-port de-embedding procedure can further eliminate the parasitics associated with the dangling leg in the source terminal. The impacts of the accuracy of the de-embedding technique on device modeling and simulation are also discussed. Index Terms--De-embedding, MOSFET, parasitics, scattering parameters.

A miniaturized common-mode filter composed of multiple substrates with positive and negative coils formed on alternate substrates is proposed in this paper. The pattern of each positive coil is interlaced with that of each negative coil, whereby when the positive and negative coils are alternately stacked, the positive coil do not overlap the negative coil. With such offset configuration, the parasitic capacitance introduced between positive and negative traces is reduced, so the thickness of each substrate can be decreased and the size of the entire filter is effectively reduced. Good agreements between simulated and measured results are demonstrated. Further, the effectiveness of this filter is confirmed by eye diagram and radiation emission measurements. Index Terms--Common-mode filter, differential signal, low-temperature co-fired ceramic (LTCC), mixed-mode S parameters, multilayer.

This paper describes the design of millimeter-wave wide-band monolithic GaAs passive high electron-mobility transistor (HEMT) switches using the traveling-wave concept. This type of switch combined the off-state shunt transistors and series microstrip lines to form an artificial transmission line with 50-[ohm] characteristic impedance. A 15-80-GHz single-pole double-throw (SPDT) switch in conjunction with quarter-wavelength impedance transformers demonstrates an insertion loss of less than 3.6 dB and an isolation of better than 25 dB. Another type of wide-band switch was designed by using a series HEMT switch to replace the quarter-wavelength transformer, and the operating band can be extended to dc. With this scheme, dc-80-GHz single-pole single-throw (SPST) and dc-60-GHz SPDT switches are also developed with compact chip size. From dc to 80 GHz, the insertion loss and isolation of the SPST switch are better than 3 and 24 dB, respectively. The SPDT switch has an insertion loss of better than 3 dB and an isolation of better than 25 dB from dc to 60 GHz. The analysis of circuit characteristics and design procedures are also included. It is concluded that the device periphery can be selected for the desired bandwidth, while the number of transistors is decided to achieve the isolation. Index Terms--High electron-mobility transistor (HEMT), switch, traveling wave.

This paper proposes a new design method for passive FET switches in the millimeter-wave (MMW) regime. In contrast to the conventional resonant-type switch design method, this passive FET switch circuit utilizes impedance transformation to compensate the drain--source capacitance effect for the off state at high frequencies. By means of this new design concept, a Q- and V-band monolithic-microwave integrated-circuit single-pole double-throw (SPDT) switches using a GaAs pseudomorphic high electron-mobility-transistor process are demonstrated. The Q-band SPDT switch has a measured isolation better than 30 dB for the off state and 2-dB insertion loss for the on state from 38 to 45 GHz, while the V-band switch also shows a measured isolation better than 30 dB for the off state and 4-dB insertion loss for the On state from 53 to 61 GHz. The obtained isolation performance using this design approach outmatches previously published FET switches in the MMW frequency range. Index Terms--High electron-mobility transistor (HEMT), millimeter wave (MMW), monolithic microwave integrated circuit (MMIC), switch.

The reductive dechlorination of carbon tetrachloride (CT) was examined in the presence of free iron ions ([Fe.sup.2+]), sulfide ions ([S.sup.2-]), and freshly precipitated ferrous sulfide (FeS) as reducing agents, and vitamin [B.sub.12] as organic amendment. The reductive dechlorination of CT by the reducing ions [Fe.sup.2+] and [S.sup.2-] in homogeneous phase resulted in the formation of variable amounts of the mono- and di-dechlorination products chloroform (CF) and dichloromethane (DCM). In the ferrous chloride (Fe[Cl.sub.2]) solutions (200 mM) where [Fe.sup.2+] was the only electron source, 76% of the original CT was depleted within 1/2 h and about 28% and 8% went to CF and DCM, respectively, at a pH of 3.1 and with no buffer present. These same dechlorination products were observed in unbuffered sodium sulfide ([Na.sub.2]S) solutions (110 and 200 mM) with [S.sup.2-] as the electron source at pH 13.4. Dechlorination products were also observed in heterogeneous systems where FeS (75-200 mM) acted as the bulk reductant and the addition of vitamin [B.sub.12] (0-4 mM) resulted in an enhancement of the dechlorination reaction. When 4 mM of vitamin [B.sub.12] were added to 200 mM FeS, CT was removed continuously and the amount of CF and DCM formed increased significantly over time, yielding a mass recovery of 40% and higher after 1 h and a pseudofirst-order rate constant of 1.91 [h.sup.-1]. The reductive dechlorination of CT in the absence of vitamin [B.sub.12], resulted in a slower disappearance of CT and the formation of smaller amounts of CF and DCM accounting for only 1% of the mass loss in the 75 mM FeS suspensions to 15% in the 200 mM FeS suspensions after 2 h. DOI: 10.1061/(ASCE)0733-9372(2002)128:1(94) CE Database keywords: Abatement and removal; Contaminants; Organic matter; Sulfides; Chlorides.

Temperature-dependent characteristics of an n+-InGaAs/n-GaAs composite doped channel (CDC) heterostructure field-effect transistor (HFET) are examined. The n+-InGaAs/n-GaAs structure is advantageous because it reduces leakage current and provides good carrier confinement in the channel.

A Pd/InP metal-oxide semiconductor (MOS) Schottky diode has been developed, with high hydrogen sensitivity and linear hydrogen response. When there is an oxide layer, barrier height is increased and hydrogen sensitivity improved, even at lower operating temperatures.

A new camel-like high-barrier gate field-effect transistor (FET) with a high breakdown voltage and low leakage current is described. The device shows promise for high-temperature applications.

Research into the design and fabrication of a pseudomorphic high electron mobility transistor is presented. The performance of the device at temperatures from 300 to 450K and gate-to-drain voltage are analysed.

The fabrication of two InGaP/GaAs resonant tunneling bipolar transistors with different superlattice structures in the emitters is described.

The fabrication of a novel multiple-sate switching device using InP/A1InGaAs heterojunction bipolar transistor structures is reported.

In this paper, a transmission-line type of input impedance model originally developed by King et al. [4] for the insulated dipole antenna embedded in a homogeneous dissipative medium is extended to the case of insulated coaxial slot antenna. Physical construction of the latter indicates the presence of additional current path(s) inside the feed line, which shall lead to the shortening of its resonance length. This effect is taken into account in the impedance model and verified by experiments. Furthermore, a simple strategy for optimizing the applicator's impedance-matching performance is also described and verified. Excellent agreements observed between theoretical and measured [S.sub.11] data indicate that these models can be relied upon when designing an efficient applicator for interstitial microwave hyperthermia. Index Terms - Input impedance, insulated dipole antenna, insulated coaxial slot antenna, interstitial microwave hyperthermia.

The objective of this paper is to present a novel approach for limiting harmonic and improving reactive compensation for industrial power systems using single-tuned filters. The unique feature of the developed power distribution model is that it incorporates both the filter capacity and resonant point as design parameters. The model also considers the detuning effects due to temperature and frequency variations, as well as manufacturing tolerances. The proposed approach was implemented as a PC-based computer code, and it was integrated with a user-friendly graphical user interface. The developed analysis tool was employed to solve the harmonic problems of several industrial plants, and the results all showed great improvements after using this computer tool. Index Terms - Filter, harmonic distortion, reactive compensation, total harmonic distortion.

Computer simulations were conducted on the display properties of chiral-homeotropic liquid crystal cells. Results show that the cells exhibit ideal light transmission, operation voltage and contrast ratio. The optimal twist angle for voltage dependence and wavelength suppression is from 90-degrees to 150-degrees. The operation mode may be applied to reflective and transmissive displays.

A fast algorithm for determining the near-field characteristics of an insulated dipole antenna (IDA) embedded in a homogenous dissipative medium is described in this paper. A thin-wire-approximation type of analysis is followed here. In this case, radiation is considered to originate from a filamentary current flowing along the axis of the dipole, which is surrounded immediately by the ambient dissipative medium. The translational symmetry inherent in the resultant radiation integrals is then exploited to speed up the computation. In one case studied, the basic thin-wire approach that uses no symmetry property is found to yield accurate results in approximately 380 times less CPU time than the traditional King-Casey approach. In another case, use of symmetry property further reduces the CPU time by a factor of 7; additional reduction in CPU time is possible by taking into account the near-field nature of the problem.

Transonic limit-cycle oscillations (LCO) can be studied using the forced oscillation behavior of a flaperon. Flaperon oscillations are studied using a rigid half-model of a combat aircraft. A clockwise hysteresis loop to the flap deflection angle in the hinge moment response provides information on instability. LCO can be removed by the use of flow control devices. Details of the experiment and the results are given.

Radiometric signal received by an open-ended rectangular waveguide probe in direct contact with a bilayered biological tissue is analyzed by the FDTD method. Two-layer tissue model consists of an outer thin skin layer over a semi-infinite fat layer is analyzed for a X-band total power radiometer. A spherical tumor with same permittivity as, but slightly higher temperature than, the surrounding normal fat tissue is assumed to exist inside the fat tissue. Active probe characteristics are analyzed first using the FDTD method for a propagating, sinusoidally time-varying, T[E.sub.10] type of excitation source. For the same waveguide probe operated as the radiometer antenna, radiometric weighting factors associated with individual tissue cells are then derived from the FDTD calculated field values. Near field radiating characteristics of the probe and radiometric signals determined for tumors of various size and depth are discussed. Presence of the skin is found to result in lower power transmission coefficient across the probe aperture and significantly lower absorbed powers by fat; both of these contribute to much lower radiometric signals observed.

In this paper, propagation characteristics of even-symmetric hybrid modes in a waveguide-shielded microstrip in the presence of a resistively coated dielectric layer affixed to the top cover of the housing is analyzed with the method of lines. The resistive boundary condition is employed to model the resistive film. A shielded microstrip line having a unity strip-width-to-substrate-thickness ratio (i.e., w/h(sub 1) = 1) placed on top of a 0.635-mm-thick alumina substrate is considered. Based on a 10h(sub 1) X 7h(sub 1) reference housing, four different housing arrangements are obtained by varying the structural parameters of the resistively coated dielectric layer. Results obtained indicate that the effects of both the housing walls and the resistively coated upper dielectric layer on the dominant (quasi-TEM) mode are insignificant and may be ignored when frequency is above 15 GHz. For the higher order modes, resistive film appears to be transparent when film resistance is greater than about 1 k-Omega, it behaves as a good conductor when film resistance is much smaller than 100 Omega, and in between it results in nonlinear (and even oscillatory) higher order modal behaviors. Apparently, due to the increasing field concentration inside the upper dielectric (as suggested by the increasing Epsilon(sub reff)) for a given mode, both the maximum attenuation and the film resistance needed to achieve it increase with frequency and dielectric constant of the upper dielectric layer.

The performance of a resistively coated dielectric strip used to suppress the first TM-type resonant backscatter associated with a two-dimensional slotted conducting rectangular shell is analyzed in this paper using the moment method technique. Results obtained indicate that almost perfect resonance damping performances are attained when a finite-dimensioned resistively coated dielectric strip with dielectric constant Epsilon(sub r) = 4 - j0.4 and film resistance R(sub s) = 188.5 ohms is placed: (1) at the slot (which directly faces the normally incident TM-polarized plane wave), (2) on the interior perimeter of the shell adjacent to the slot, or (3) at the center of the back wall of the shell. Poorer damping performances are observed, however, when the resistively coated dielectric strip is placed at other positions and/or with the same or higher film resistance. Finally, it is also shown that in general the knowledge of the waveguide theory can be used advantageously in the placement of the resistively coated dielectric strip for achieving best resonance damping performance.