Search

• Realization of sound insulation with newly designed hexagonal-shaped Helmholtz resonators. • Systematic analyses of the working mechanism of the metadevice. • Methodical experimental approach with validation of two- and three-dimensional (2D and 3D) numerical methods. • Realization of reconfigurability and active control of the full noise reduction system. In this study, we propose a new reconfigurable hexagonal-shaped Helmholtz resonator with a slit in each side. Numerical and experimental investigation of a single unit cell and the whole acoustic metamaterial chamber highlights the reliability and feasibility of the proposed metastructure. Highly efficient sound insertion loss can be captured with a simple and easily accessed resonator. By carefully designing rotation support in each unit cell and manufacturing a 3D printed base with periodic holes, the assembled resonators can be easily rotated, and the finite acoustic metamaterial chamber can be tuned to another configuration without the need of reprinting and redesigning the whole structure. The mechanisms of the proposed system are systematically explained by numerical computation (2- and 3-dimensions), band structure analysis, insertion loss and the corresponding experimental measurements. Specifically, the flat bands in the band structure reveal the weak coupling between the neighbouring resonators, and the highly trapped acoustic energy indicates that the bandgap originates from the local resonance mechanism. Thus, even one single unit in the system can efficiently attenuate the noise at mid frequencies, and the effects become better when the number of resonators increases. These phenomena can also be explained by the sound pressure map in the waveguide analysis and the characteristics of the insertion loss. Interestingly, by changing the configuration of the full chamber, the device can keep the insertion loss at a high level, while exhibiting a better ventilation ability. Therefore, with the high degree of freedom of tuning, it is possible to actively control the whole system to simultaneously achieve efficient noise cancelling and free airflow. The reconfigurable, scalable, feasible and controllable system can be easily applied to several practical scenarios like the silent zone in the city center, the ventilated noise isolate device for the machines, and optically transparent ventilation sound-insulating structures. [Display omitted] [ABSTRACT FROM AUTHOR]

A 3.5 GHz low insertion loss variation phase shifter has been designed and fabricated on standard 0.18‐μm CMOS process. To achieve over 360° continuously phase tuning range, the phase shifter consists of a switch type phase shifter (STPS) and a reflection type phase shifter (RTPS). The phase‐invertible variable attenuator (PIVA) topology which can provide two states with 180° phase‐shift while maintaining low amplitude imbalance is adopted. The RTPS provides over 189° continuously phase tuning. The experimental results show that the 3.5 GHz phase shifter demonstrates over 360° continuously phase tuning range with low insertion loss variation of 1 dB at 3.5 GHz. The maximum insertion loss is 13.5 dB at 3.5 GHz and the dc consumption is zero. The chip size is 1.08 mm × 0.82 mm. [ABSTRACT FROM AUTHOR]

A novel wideband eight-way radial waveguide power combiner has been proposed in this paper. The proposed radial waveguide power combiner consists of a commercial N-type connector, a regular-octagon waveguide cavity, eight matching circuits, and eight coaxial-to-ridge waveguide transitions. The introduction of matching circuits is used to improve matching performance in the regular-octagon waveguide cavity. Besides, in order to guarantee the bandwidth performance and facilitate applications, eight coaxial-to-ridge transitions as output ports were also designed to connect ridge ports of the radial waveguide power combiner. Therefore, the overall performance of the proposed waveguide power combiner is enhanced over the wideband range. For validation, a sample eight-way radial waveguide power combiner has been designed, fabricated, and measured. The measured results show that the return loss (S11) and insertion loss (S21) are better than 20 dB and 0.5 dB, respectively, in the whole frequency range from 4 to 8 GHz (with 66.6% fractional bandwidth). The measured results reasonably agree well with the simulation ones. Compared with some other radial waveguide power combiners, the completed radial waveguide power combiner exhibits lower return loss, lower insertion loss, more compact size, and prominent bandwidth performance. [ABSTRACT FROM AUTHOR]

A graph-controlled insertion-deletion system is a regulated extension of an insertion-deletion system. It has several components and each component contains some insertion-deletion rules. These components are the vertices of a directed control graph. A transition is performed by any applicable rule in the current component on a string and the resultant string is then moved to the target component specified in the rule. This also describes the arcs of the control graph. Starting from an axiom in the initial component, strings thus move through the control graph. The language of the system is the set of all terminal strings collected in the final component. In this paper, we investigate a variant of the main question in this area: which combinations of size parameters (the maximum number of components, the maximal length of the insertion string, the maximal length of the left context for insertion, the maximal length of the right context for insertion; plus three similar restrictions with respect to deletion) are sufficient to maintain computational completeness of such restricted systems under the additional restriction that the (undirected) control graph is a path? Notice that these results also bear consequences for the domain of insertion-deletion P systems, improving on a number of previous results from the literature, concerning in particular the number of components (membranes) that are necessary for computational completeness results. [ABSTRACT FROM AUTHOR]

In this article, a miniaturized ultra‐high frequency (UHF) microstrip traveling wave antenna (TWA) array for cm‐level 2D identification (ID) and position detection systems is proposed. The proposed miniaturized TWA array with nine reading zones for ID and position detection systems has been reduced in size by utilizing LC‐baluns and a microstrip TWA array. It covers the authorized universal UHF radio frequency ID band (840‐960 MHz), has low insertion loss (0.8 dB), and high isolations between TWAs are ≤30 dB. The sensing precision of the proposed TWA array is approximately 1.5 cm and its physical size is 95 × 95 mm2 (~1/4 λ0 at 915 MHz). [ABSTRACT FROM AUTHOR]

In this paper, an ultra-compact low-pass filter (LPF) with wide stopband is proposed based on lumped L-C structure in through-silicon via-based 3-D stacked configuration. The spiral inductor (L), interdigital capacitor (C), and the proposed LPF are theoretically analyzed based on parasitic parameters and equivalent circuit models. To evaluate the characteristics, the proposed LPF is simulated by HFSS, fabricated with CMOS-process-compatible technology, and measured with de-embedding method. Simulation and measured results are in good agreement. Compared with the other literature, the proposed LPF has the most compact size of $0.028\lambda _{g }\times 0.017 \lambda _{g}$. ($\lambda _{g}$ is the guide wavelength at $f_{c}$.) With the cutoff frequency at 10.05 GHz, the filter has an insertion loss of 0.14 dB and reflection loss over 13 dB from dc to 9 GHz in the passband. The suppression levels are better than 20 dB from 20.4 up to 40 GHz in the stopband. [ABSTRACT FROM AUTHOR]

Novel design methods for implementing continuous centre-frequency and bandwidth tunability are reported. Coupling bandwidths are tuned through the mechanical rotation of a metallic plate suspended between resonators. Centre-frequency tuning is achieved via the vertical actuation of a moving part mounted within each resonator. In addition, each resonator and transformer is designed so that motors can be housed within them - adding tunability without compromising the overall filter volume. A second-order filter, based on combline cavity structures, capable of bandwidth tunability of 49-67 MHz for all centre frequencies in the range of 1.751-1.998 GHz is presented. Passband insertion loss is kept below 1.2 dB for all tuning states with return loss above 10 dB. A five-pole filter is also fabricated with centre-frequency tunability of 14% from 1.764 to 2.015 GHz and 15 dB bandwidth tunability of 107% from 41 to 85 MHz. Midband insertion loss is kept below 1.4 dB in all tuning states. The five-pole filter is compared to other tunable filters in the UHF range and is shown to reduce midband insertion loss by 36% from the next best filter (2.2-1.4 dB). [ABSTRACT FROM AUTHOR]

Abstract A high-power X-band (9.3 GHz) compact RF rotary joint has been designed, fabricated and tested in Tsinghua University. Simulation results illustrated that RF parameters (the scattering matrix) of this rotary joint keep stable in different rotation angle. Cold measurement using Vector Network Analyzer confirmed the simulation results. The maximum reflection was below −25 dB, the insertion loss was less than 0.1 dB, and the variance of output phase shifts was below 0.2 degree while rotating the joint. High-power test under a 1.6 MW X-band magnetron also showed good results. The design, cold measurement and high-power test of the RF rotary joint are presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: A novel controllable wideband filtering power divider (FPD) with sharp roll‐off skirt and good isolation is presented in this article. By introducing a pair of coupled lines and several uniformed quarter‐wavelength microstrip lines to the power divider, a wide flat passband with good selectivity is achieved. A resistor is then arranged between the 2 coupled line structures to obtain good isolation. Even‐mode and odd‐mode approach is applied to deduce the design equations of the proposed FPD. The center frequency can be adjusted flexibly by simply controlling the length of the coupled lines and the other microstrip lines. Eventually, the proposed power divider centered at 2.3 GHz with a fractional bandwidth of 75% is fabricated and measured for verification. The measured minimum in‐band insertion loss is 0.3 dB, while the isolation is better than 20 dB. Good agreement is shown between the simulated and measured results. [ABSTRACT FROM AUTHOR]

A new octave bandwidth high selectivity compact microstrip diplexer working in the band from 10 to 20 GHz is presented, intended to be a part of an electro-optical interferometer covering the whole frequency band. The circuit is based on the combination of hybrid couplers and bandpass filters both on the microstrip technology. The diplexer provides two output frequency bands which cover the 10–14 GHz (relative bandwidth of 33%) and the 16–20 GHz (relative bandwidth of 22%) ranges, respectively, with a stop band in between from 14 to 16 GHz. Measured results show a insertion loss level of 3.3 dB for both output bands and high selectivity performance, exhibiting a rejection level between output bands higher than 20 dB and return loss better than 10 dB in all ports. [ABSTRACT FROM AUTHOR]

In this paper, the design methods for four-way power combiners based on eight-port and nine-port mode networks are proposed. The eight-port mode network is fundamentally a two-stage binary four-way power combiner composed of three magic-Ts: two compact H-plane magic-Ts and one magic-T with coplanar arms. The two compact H-plane magic-Ts and the magic-T with coplanar arms function as the first and second stages, respectively. Thus, four-way coaxial-to-coaxial power combiners can be designed. A one-stage four-way power combiner based on a nine-port mode network is also proposed. Two matched coaxial ports and two matched rectangular ports are used to provide high isolation along the E-plane and the H-plane, respectively. The simulations agree well with the measured results. The designed four-way power combiners are superior in terms of their compact cross-sectional areas, a high degree of isolation, low insertion loss, low output-amplitude imbalance, and low phase imbalance, which make them well suited for solid-state power combination. [ABSTRACT FROM PUBLISHER]

An on-chip triplexer based on cascaded tilted multimode interference (MMI) couplers has been demonstrated to separate the 1310 nm wavelength band into one port and 1490 nm and 1550 nm wavelength bands into the other two ports respectively. By utilizing the dispersive self-imaging and pseudo self-imaging, the device length is not critically determined by the common multiple of beat lengths for different wavelengths. The total device size can be reduced to ∼ 450 μ m, which is half of the butterfly structure reported. The whole device, fabricated with only one fully-etching step, is characterized with <−15 dB low crosstalk (CT) and ∼ 1 dB insertion loss (IL). [ABSTRACT FROM AUTHOR]

This paper presents a quasi-elliptic wideband bandpass filter (QEWB-BPF) constituting a pair of lumped-element dual-resonance resonators (LE-DRRs) with mixed electric and magnetic coupling (MEMC). Two resonant modes of proposed LE-DRR can be controlled separately. Due to virtual ground in LE-DRR, the cancelling effect of two paths of MEMC, and inductive perturbation, four TZs are realized around the passband. As an example, a QEWB-BPF with measured central frequency (CF) at 1.82 GHz and 3 dB fractional bandwidth (FBW) of 24.4% is designed and fabricated. The measured minimal insertion loss (IL) is 0.95 dB, and a 30 dB rejection upper stopband from 2.11 to 4.79 GHz is also obtained. The fabricated QEWB-BPF has a compact circuit size of 0.133λg× 0.215λg. [ABSTRACT FROM PUBLISHER]

The influence of the liquid with the different values of conductivity, permittivity, and viscosity on the characteristics of the slot mode in the structure consisting of delay line with propagating shear – horizontal acoustic wave of zero order (SH 0 ) and upper piezoelectric plate separated by the air gap was experimentally investigated. The delay line made of the Y-X lithium niobate plate 0.2 mm thick contained two interdigital transducers for the excitation and reception of acoustic wave in the frequency range of 2.6–3.8 MHz. The upper plate represented the 0.5 mm thick plate of Z-X lithium niobate. The excitation of the slot mode led to the appearance of the sharp resonant peaks on the frequency dependencies of insertion loss and phase of the output signal. It has been found that the depth and frequency of these peaks depend on the parameters of liquid contacting with the upper plate. The possibility of the use of the slot mode in the pointed structure for the identification of liquids with the different values of the conductivity, viscosity, and permittivity was shown. The qualitative explanations of the obtained experimental results are presented. [ABSTRACT FROM AUTHOR]

The measurement of acoustic properties for passive-material samples is strongly interfered by reverberations in a limited space. A multichannel inverse filter (MIF) can achieve spatio-temporal focusing by retransmitting the optimal signal estimated from multichannel impulse responses of the transmitter channel and the underwater acoustic channel. To decrease the influence of reverberations on measurements and improve the measurement precision, a MIF is employed to measure the echo reduction and insertion loss, respectively. The method is demonstrated by simulations and experiments, which were performed in a cylindrical tank to measure the two acoustic parameters for a steel plate sample. [ABSTRACT FROM AUTHOR]

Microfluidically repositionable selectively metallized plates (SMPs) are utilized for the first time to design and realize microstrip line combline filters with wide frequency tuning and high power-handling capability. A continuous frequency tuning range of 2.7:1 is achieved by utilizing tight coupling between the SMP and open-ended microstrip line resonators in order to change their length for tuning from 2.5 to 4 GHz and capacitively load one of their open ends for tuning from 1.5 to 2.5 GHz. The unloaded quality factor (Qu) of the resonators is maintained relatively constant (210–190) across the entire tuning range allowing for the low insertion loss (IL) and high power-handling capability. Specifically, a ~5% constant fractional bandwidth fourth-order filter design is discussed and experimentally verified. The filter exhibits less than 3-dB IL across the 2.7:1 tuning range. It is shown that the filter’s power handling capability can reach up to 15 W under constant average power excitation. [ABSTRACT FROM PUBLISHER]

Two rotary joints perpendicularly fed by the substrate integrated waveguide (SIW) feeder are presented in this paper. The planar SIW feeder excites the circular waveguide with the desired rotational symmetric mode through a circular slot, whose effect can be modeled through a horizontal magnetic current on the top surface of the SIW. First, a single-layer SIW feeder is designed in the rotary joint with simple configuration. After that, a dual-layer SIW feeder is proposed to improve the performance of the single-layer version, especially for the bandwidth. Both of them have two controllable transmission poles, which can be used to optimize performance. After introducing the design principle and process, two rotary joints perpendicularly fed by different SIW feeders are fabricated and measured. For the dual-layer feeder rotary joint, it is able to operate from 11.1 to 12.4 GHz. Within an 11.1% relative bandwidth, its insertion loss is less than 1.21 dB and return loss is better than 10.85 dB when being rotated at different angles. [ABSTRACT FROM PUBLISHER]

In this paper, a new family of low-profile high quality factor cavity resonators, termed distributed resonators, is introduced. Initially, the theory of operation of the proposed distributed resonator is presented regarding two, three, and four coupled resonator elements. Based on this, a further-improved arrangement of resonator elements is proposed. It is shown that the height of the individual resonator can be controlled by the number of resonant elements and can be almost arbitrarily low. As an experimental verification, a three-pole filter operating at 1800 MHz with a bandwidth of 40 MHz is designed and fabricated. The individual resonator of this filter comprises 25 individual resonant elements, with an overall cavity height of 7 mm, or 15°, and an unloaded quality factor of 1900. The height of the presented filter is significantly lower than any other air-filled filter cavity solution available in the literature. The measured insertion loss of the filter is 0.5 dB, which is in excellent agreement with the theoretically predicted value of 0.4 dB. [ABSTRACT FROM PUBLISHER]

In this paper, a GaAs absorptive single-pole double-throw (SPDT) RF switch and its application to a 2.4-GHz switched beamformer module are presented. The proposed absorptive SPDT RF switch features low-power consumption and low insertion loss with good output matching both in the on and off states. Specifically, the measured insertion loss in the on state is less than 1 dB, and the measured input and output return losses are both better than 11.2 dB from 1.9 to 2.6 GHz. The measured output return loss in the off state is better than 15 dB, and the measured isolation is better than 24.7 dB in the same frequency range. Two proposed absorptive SPDT switches are then employed to form an absorptive single-pole four-throw RF switch, and it is integrated with a miniaturized $4 \times 4$ Butler matrix using the integrated passive device (IPD) technology to achieve a compact 2.4-GHz switched beamformer module with a very low profile. Specifically, the module size is 4.9 mm $\times5$ mm with a thickness of only 0.4 mm. The IPD beamformer module is then used to realize a low-profile 2-D scanning antenna array, and 16 different beams in azimuth and elevation dimensions are successfully generated. [ABSTRACT FROM PUBLISHER]

A compact spurious free, quad-band, band-pass filter (BPF) having independently controllable and widely spaced frequency bands is proposed. The design consists of a basic BPF to which the authors introduce transmission zeros (TZs) in the frequency response using T-shaped stubs loaded with a modified ring resonator (MRR) thereby creating the four passbands. This design results in very high band-to-band isolation. The TZs are obtained by transversal signal path cancellation and also due to the loaded T-shaped stubs. The BPF consists of a stepped impedance low-pass filter which provides spurious free out of band characteristics up to 20 GHz. By changing the tapping position of the MRR, the frequencies of the TZs can be adjusted to get the desired pass band characteristics. The proposed quad-band filter provides low-insertion loss (<1 dB) at the four passbands centred at 2.4, 5.1, 7.7 and 10.1 GHz. The simulation results of the filter are verified experimentally. [ABSTRACT FROM AUTHOR]

Fabrication and RF characterization of GaN HEMT on silicon and sapphire substrate are done, and henceforth, forming a Verilog-A model by experimental results obtained from RF characterization of GaN HEMT. This model is implemented for designing of RF switch in Cadence's spectre, to evaluate the substrate effects on RF switch performance. The variation in isolation, insertion loss, and return loss for a frequency range of 2.5 GHz is found as 15 dB/10 dB, 3 dB/2.2 dB, and 0.7 dB/0.4 dB for silicon/sapphire substrate, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT A compact planar microstrip branch-line coupler using equal difference structures was implemented and measured. Using the equal difference structure effectively reduced the quarter-wavelength microstrip line and minimized the branch-line coupler dimension as a result of a novel triangular profile of the structure streamlining the circuit area. Compared with that of conventional planar microstrip branch-line couplers, the optimized area of the proposed coupler was reduced by 84.2% at a 900 MHz operating frequency. The measured insertion loss, isolation, and return loss performances achieved superior results than 3.9, 23, and 16 dB, respectively, and the measured phase difference between the two output ports was 90° ± 0.1°. Notably, a coupler using equal difference structures can be implemented in standard printed circuit board processes without any lumped elements, bonding wires, or via-holes, easing integration with wireless communication systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:664-668, 2017 [ABSTRACT FROM AUTHOR]

Sonic crystals are periodic arrangement of scatterers made of material with low acoustic impedance or sound hard materials [1] . Sonic crystals have numerous applications such as green belts and sound barriers. Here we showed that a typical maze structure at children playground can attenuate noise effectively for frequencies ranging from 12.5 Hz to 20,000 Hz. The original designer for the maze structure probably does not have that in mind. The maze structure can be viewed as a sonic crystal structure with sound attenuation characteristics. We found that the maze was able to attenuate noise up to 17.9 dBA for frequency range below 1000 Hz and 23 dBA for higher frequency range up to 20,000 Hz. The maze structure was able to mitigate noise at a wide range of frequencies in addition to the center frequency ( f c ) of 478 Hz which was estimated based on the Bragg’s Law. The periodic effects of the maze was also proven by numerical studies. Our results demonstrated that the maze structure commonly found in children playgrounds was able to attenuate noise covering the whole human hearing range. [ABSTRACT FROM AUTHOR]

Design of planar Substrate Integrated Waveguide (SIW) and Half Mode Substrate Integrated Waveguide (HMSIW) Band Pass Filter (BPF) loaded with periodic array of longitudinal slots are proposed in this paper. The proposed method introduces simple periodic reactive slots which have the property to create resonance to obtain stopbands at multiple frequencies. Transmission zeroes as well as Insertion Loss of the BPFs designed by using these technique are relatively easy to control. The property of these periodic slots is further analyzed to reach a concrete conclusion which provides the design engineers luxury to choose stopbands as per individual applications. Major spectrum of Microwave X-band and Ku-bands are covered with minimal Insertion Loss. Nearly 50% reduction in size is also obtained by using HMSIW structures. The designs are fabricated and the concept is successfully validated with measured results over a material of dielectric constant 3.2 and thickness of 30 mils. Methods proposed in this paper are extremely simple to design and suitable for Industrial or Scientific productions. [ABSTRACT FROM AUTHOR]

This paper presents the detailed design, fabrication, and measurement of cavity resonators and filters for silicon (Si)-based millimeter-wave integrated circuits. The design of the cavity resonators and filters is conducted using Ansoft High Frequency Structure Simulator. The cavity resonators and filters are fabricated on a 4-in Si substrate using the air-gapped microcoax technology, which is based on a multilayer low-temperature copper Damascene process. The fabricated cavity resonators have measured unloaded quality ( Qu ) values of 666 and 864 for 36 and 60 GHz, respectively. Two-pole bandpass cavity filters have achieved an insertion loss close to 0 dB and a return loss better than 20 dB for both 36- and 60-GHz passbands. The cavity resonator and filter have simple structures and avoided excessive global optimization for the design. Hence, the accuracy, time, and complexity of the design can be improved significantly. The fabrication technology demonstrates the advantages of ultralow loss and dispersion, perfect impedance matching, pure transverse electromagnetic propagation mode, and ultrahigh isolation and power-handling capability. Furthermore, the process has a low thermal budget and is fully compatible with CMOS back-end-of-line (BEOL) process, which can be integrated with other air-gapped microcoaxial components to realize a high-performance microwave system on chip. [ABSTRACT FROM PUBLISHER]

Defected coplanar waveguide (CPW) resonator has been analyzed, and multi-band bandpass filters with individually controllable passband have been developed. New dual-band and tri-band bandpass filters which center at 2.4/3.5/5.2 GHz have been designed, fabricated and measured. The measurements demonstrate the new presentations. The measured filter passband insertion losses are less than 2.7 dB. It has been noticed that the filter center frequencies can be individually controlled, and the bandwidths can be individually adjusted. Advantages of the new design are not only its simple and compact circuit topology, miniature circuit size, but also its less electromagnetic leakage. [ABSTRACT FROM AUTHOR]

This paper presents a new symmetrical interdigital-loaded microstrip structure. The symmetrical structure can be applied to design a filter that can work at different frequencies. The filter has similar in-band response at each working frequency with low insertion loss. Based on the proposed structures, a low-loss six-pole high temperature superconducting (HTS) filter with four different working states is designed and fabricated. The center frequency of the filter can be tuned discretely from 1.382 GHz to 1.193 GHz. All four states have similar in-band characters, whereas the insertion losses are less than 0.3 dB. The measured results are consistent with the simulations. [ABSTRACT FROM AUTHOR]

Objectives: We present a method to account for the effects of the hearing protection devices (HPDs) for use with the 8 hours equivalent A-weighted energy (LAeq8) criterion. The method involves the calculation of the LAeq8 equivalent unprotected free-field dose (LAeq8EUFF), which is obtained by using the insertion loss (IL) data of the HPD together with free-field pressure measurements.Methods: The method was validated against the historical the U.S. Army Medical Research and Materiel Command walk-up study data with volunteers exposed to simulated large weapon noise wearing a range of HPDs. The IL data were obtained using standard acoustical test fixtures fitted with the matching HPDs in replicated field tests and using shock tubes at conditions comparable to the actual exposure intensities. Logistic regression calculations were performed to correlate the LAeq8EUFF values against the walk-up study outcomes to determine the L(95,95) threshold for the protection of 95% of the population with 95% of the time.Results: Data comparison shows that L(95,95) is 89 dBA, which is slightly higher than the 85 dBA criterion but falls in the 80 to 90 dBA range as used by various NATO nations.Conclusions: Therefore, considering the limitation of the walk-up dataset, it is conservative to adopt the 85 dBA threshold for general application. [ABSTRACT FROM AUTHOR]

We use cache-sensitive memory layouts to improve search performance in ordinary binary search trees, without increasing the time complexity of insertion or deletion. Our approach does not require changes to the structure of the nodes or the rebalancing strategy of the tree. Cache-sensitivity is maintained with a memory-layout invariant that keeps a given number of neighboring nodes in the tree stored in the same cache block. We show how to preserve it using worst-case constant-time operations executed when the tree changes. In our extensive experiments, the invariant consistently improved the search performance of large AVL and red-black trees by 26-32%, on synthetic data as well as realistic search tree operations extracted from a database benchmark. We also compare binary search trees with several cache-sensitive B-trees, and non-dynamic approaches for laying out tree nodes in a multi-level memory hierarchy. [ABSTRACT FROM AUTHOR]

This study presents a 4-bit phase shifter with a maximum phase shift degree of 75° based on packaged metal-contact single-pole double-throw (SPDT) radio frequency microelectromechanical system (RF MEMS) switches mounted on a 20 mil RO4350 substrate and assembled with its driver module on a 4-layer printed circuit board (PCB) board. Electric length of 10° and characteristic impedance of 61.7 Ω are selected for T-stub matching. Standard PCB processing makes it easy to develop and suitable for taking place of mechanical tilt employed in recent base station. Measurements indicate a maximum insertion loss of 1.37 dB at 2.7 GHz and a minimum return loss of 11.71 dB. The phase accuracy is within 1.75° at 2.7 GHz. [ABSTRACT FROM AUTHOR]

A novel, compact, TM01-TE10 mode power divider and a novel, compact, four-way TE10-TM01 mode power combiner were theoretically designed and experimentally tested as a proof of principle. The theoretical and experimental S parameters are consistent with each other. High-power experiments show that their power capacities are no less than 1.5 GW and 3 GW, respectively. The devices have the merits of high power capacities and low insertion losses. [ABSTRACT FROM AUTHOR]

This paper presents the detailed design, fabrication, and measurement of right-angled microcoaxial bends for silicon (Si)-based radio frequency and microwave integrated circuits. The design of the right-angled microcoaxial bends is performed using the high-frequency structural simulator and the trained artificial neural networks (ANNs) models. The ANN models enable fast and accurate design of microcoaxial bends to achieve desired impedance. The right-angled straight and curved microcoaxial bends are fabricated by a multilayer copper (Cu) Damescene process, which has a low thermal budget and is fully compatible with a complementary metal–oxide–semiconductor back-end-of-line process. Insertion loss less than 0.04 dB at frequency from 0.1 to 40 GHz is realized for both straight and curved bends. The measured return loss is less than −20 dB at frequency from 0.1 to 40 GHz for both microcoaxial bends. The impedance for both microcoaxial bends is well matched to 50 $\Omega $ . Besides the low loss and the high impedance matching, the microcoaxial bends also show other advanced characteristics, including high-quality factors ( $Q$ -factors) as well as supporting pure transverse electromagnetic mode. The use of high-performance bends allows us to fold microcoaxial passive components to meander structures for miniaturization while maintain low loss and perfectly matched impedance. [ABSTRACT FROM PUBLISHER]

The boundary element method (BEM) is a commonly used method to compute the insertion loss of noise barriers having arbitrary cross-sections. For large scale three-dimensional problems, however, the BEM is not feasible. On the other hand, standardized calculation methods for noise mapping are efficient, but shapes other than the straight barrier cannot be properly calculated. Attempts to merge these two approaches by using BEM to derive correction functions based on geometrical quantities such as source and target angle as well as the path length elongation between source and receiver caused by the barrier were usually focused on a small set of barrier types, dimensions, absorptive configurations, source or receiver positions. The main objective of this study is to investigate which functions based on the most common geometrical parameters are well suited for approximating the efficiency of different types of barriers, dimensions and absorptive configurations. To achieve this, numerous combinations of 7 different barrier types, different heights and widths as well as 3 different absorptive configurations were simulated using the 2D BEM for 8 different source positions. The octave-band-wise efficiency, i.e. the frequency-dependent gain in insertion loss compared to an equally high, fully reflective straight barrier was used as a basis for the correction functions. Linear as well as polynomial models were compared yielding a polynomial of third degree in the source and fourth degree in the target angle as the best model. Effects on the error using uniform sampling in the target angle instead of a uniform receiver grid as a basis for the correction functions are also investigated. Furthermore, wide-band efficiencies based on standardized traffic emission spectra are calculated showing small errors compared to single-band errors, in particular in the high-frequency range. A linear interpolation scheme is suggested to deal with barriers having dimensions not simulated in this work. [ABSTRACT FROM AUTHOR]

This study designed a compact Ka-band open-circuited stub bandpass filter by using the low-temperature cofired ceramic technology. A novel inverted-L stub resonator was developed in the design of 37-GHz third-order bandpass filters. When the operating frequency is high, the proposed structure is highly useful for maintaining extremely low impedance levels in stubs to prevent distorting the filter performance. The design concept was validated by measuring a fabricated filter; the filter demonstrated an insertion loss of 1.9 dB, return loss of 18 dB, and bandwidth of 23.5%. [ABSTRACT FROM AUTHOR]

A low-pass single-pole-single-throw (SPST) switch is analyzed and designed in a 1.2 V 65 nm bulk CMOS RF process for applications from DC to millimeter-wave frequencies. The SPST switch has a small active chip area of only 96 μm×140 μm and shows the measured wideband performance of insertion loss lower than 3 dB and isolation higher than 22 dB from DC to 70 GHz. In particular, it achieves 1.6 dB insertion loss, 27.9 dB isolation, and 14.5 dB return loss at 60 GHz. The SPST switch also shows the measured power-handling capability of 11.5 dBm at 40 GHz and simulated switching speed of 1 ns at 60 GHz. These results clearly demonstrate that the SPST switch has potential to be used in highly-integrated CMOS radios. [ABSTRACT FROM AUTHOR]

Distribution systems are traditionally designed as radial passive systems fed from a single source. Protection coordination of such systems has been easily established assuming the system radiality. Insertion of distributed generators (DGs) into distribution systems makes the distribution system to be more active which causes redistribution of fault currents magnitudes and directions. This causes negative impacts on the original protection system coordination, since the distribution system losses its radiality and passiveness. Recently protection coordination in the presence of distributed generation has been paid a great attention. Researchers proposed various solutions to solve the protection coordination problem caused by adding DG into the distribution network. In this paper, the proposed solutions for the protection coordination problem considering the DG insertion will be illustrated, classified, and criticized. [ABSTRACT FROM AUTHOR]

Regardless of the excellent RF characteristics that microelectromechanical switches possess in variety of high frequency applications, some of these application areas require switches that could possibly withstand harsher environments like high temperature or high thermal stresses. This paper presents the finite element modeling of a compact RF MEMS DC contact switch design based on titanium material to withstand in such conditions. The switch is designed with meanders on all sides to increase the elastic recovery forces. The proposed switch dimensions are very compact with the total surface area of 0.1 mm $$^2$$ . The modelled switch is optimized for L-band that results in high isolation of 52 dB and very low insertion loss of 0.007 dB at 2 GHz with low actuation voltage of 18.5 V. [ABSTRACT FROM AUTHOR]

At first, the receiving system of the Tianma 65m radio telescope (TM65m in brief) and its noise characteristics at the L, S, C, and X four frequency bands are described. Then, a few measuring methods of system noise temperature are discussed, and the major factors affecting the noise temperature measurement are analyzed, including the errors caused by the non-linearity, feed network insertion loss, mismatch, and so on. With the Y-factor method the noise temperature of the noise source calibrated in the laboratory is verified, indicating that its accuracy attains ∼0.2K. Finally, the system noise temperatures actually measured at the four frequency bands and an analysis on the result are given. [ABSTRACT FROM AUTHOR]

An equivalent-circuit model of shield differential through-silicon vias (SDTSVs) in 3-D integrated circuits (3-D ICs) is proposed in this paper. The proposed model is verified using the 3-D full-wave field solver High Frequency Simulator Structure, showing that it is highly accurate up to 100 GHz. Furthermore, a full-wave extraction method for the resistance–inductance–capacitance–conductance (RLCG) parameters of SDTSVs is also proposed in this paper, which can be applied to all of differential transmission lines. It is shown that the results of the RLCG parameters obtained from the full-wave extraction method agree well with that from the analytical calculation up to 100 GHz, further validating the accuracy of the proposed model. Finally, using the proposed model, a deep analysis of electrical characteristics of SDTSVs is carried out to provide helpful design guidelines for them in future 3-D ICs. [ABSTRACT FROM AUTHOR]

ABSTRACT A compact microstrip lowpass filter with a very wide passband is proposed in this article. The filter is based on generalized Chebyshev filter prototype of nine degree. The filter is designed to have a cut-off frequency at 18 GHz and a return loss of better than 20 dB. The design of the proposed filter is successfully realized in theory and verified by full-wave electromagnetic simulation and the experiment. An excellent agreement between the expected and measured results is obtained. The measured results show a low insertion loss of less than 1.5 dB over the entire ultrawide passband. The fabricated filter looks attractive for wideband RF/microwave systems due to its good performance and overall physical volume. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:871-874, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel silicon asymmetric tilted slot waveguide-based polarization rotator is presented. A large birefringence in the silicon slot waveguide facilitated a compact polarization rotator of subwavelength scale. A 1287 nm long TM to TE and TE to TM polarization rotator was achieved with an extinction ratio of 10 dB and an insertion loss of less than 5 dB at an operating wavelength of 1500 nm. Further performance improvement is possible for polarization rotator designed to work on TM to TE (or TE to TM) conversion: a 711 nm long TM to TE polarization rotator with 9.25 dB extinction ratio and 2.2dB insertion loss was also numerically demonstrated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:779-785, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT This article describes the development of an optimized microstrip wideband bandstop filter (BSF) with open stubs for ultrawideband applications. Simulated results agree with the measured results, demonstrating in the experimental results a 10 dB bandwidth from 4.6 to 7.6 GHz, insertion loss (S21) of −33.9 dB, and minimum return loss (S11) of −0.40 dB at 6.1 GHz. Additionally, an equivalent circuit of the wideband BSF is built to estimate the electromagnetic simulation results for practical realization. The features of the design have a reduced size, wideband rejection, higher insertion loss, and tunable bandwidth, which can be performed by adjusting the L-shaped stubs (0.41λg and 0.29λg) toward the 50 Ω input and output ports. The designed BSF occupied the size of 0.35λg × 0.29λg. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1003-1006, 2015 [ABSTRACT FROM AUTHOR]

Acoustic filters (AFs) are key components to control wave propagation in multi-frequency systems. We present a design which selectively achieves acoustic filtering with a stop band and passive amplification at the high- and low-frequencies, respectively. Measurement results from the prototypes closely match the design predictions. The AF suppresses the high frequency aliasing echo by 14.5dB and amplifies the low frequency transmission by 8.0 dB, increasing an axial resolution from 416 to 86µm in imaging. The AF design approach is proved to be effective in multi-frequency systems. [ABSTRACT FROM AUTHOR]

A CMOS compatible AlN/SiO2/Si3N4/Si(100) surface acoustic wave (SAW) device has been fabricated and will be compared with standard AlN/SiO2-based devices. The presented filter demonstrates high potential for CMOS integrated high-frequency SAW devices. The filter insertion loss could be improved to −12.8 dB. The device exhibits high crosstalk suppression of −50 dB on a standard Si-substrate (10 $\Omega $ cm). X-ray diffraction, (scanning) transmission electron microscopy, and energy dispersive X-ray spectroscopy studies correlate the signal quality with $c$ -axis orientation of aluminum nitride films on interdigitated transducer finger electrodes. Finite-element method simulations are in good agreement with the electric measurements and show typical Rayleigh particle displacement. [ABSTRACT FROM AUTHOR]

The antenna factor (AF) above the ground plane changes with respect to the height and obtaining a height pattern of the AF with a sufficient resolution is time consuming. In this paper, a novel method is proposed to obtain an accurate AF at an arbitrary height by a single site insertion loss (SIL) measurement. A ratio of the E-field strength at the location of the antenna under calibration (AUC) to the current amplitude at the transmitting antenna port is introduced. By using this ratio, the AF of the AUC at the height can be obtained by only one SIL measurement. Unlike the conventional method, the multiple SIL measurements are no longer necessary and the proposed method remarkably reduces the measurement time. By using the AFs properly calibrated by the proposed method, the effects of antenna characteristics are significantly reduced in the normalized site attenuation measurement. [ABSTRACT FROM PUBLISHER]

Highlights: [•] The tunable lowpass filter with DGS structure was fabricated using MEMS technology. [•] The cut-off frequency and the insertion loss of the filter were studied. [•] The filter fabrication was shown and the filter has small chip size of 2.5mm×1.2mm. [ABSTRACT FROM AUTHOR]

Background Insertion of an epidural catheter for pain relief is frequently used in anaesthetic practice. Little is known regarding patients' expected vs. experienced pain and discomfort due to the epidural block procedure. The purpose of this study was to investigate the expected and experienced pain, respectively, associated with the epidural procedure in patients undergoing major abdominal surgery. Methods Thirty adult, unselected patients scheduled for elective major abdominal surgery were included in this study, which was approved by the ethics committee. Pre-operative insertion of an epidural catheter had to be a part of the anaesthetic routine procedure. Immediately before the epidural procedure, the patients were asked to grade the pain they expected from the procedure on an 11-point numeric rating system scale, ranging from 0 to 10, where '0' is no pain and '10' is worst imaginable pain. When the procedure had been carried out, the patients were once again asked to grade how much pain they had experienced. Results The median expected pain as a result of the epidural procedure was 5.0. Median experienced pain was 2.0. The median difference between the expected and experienced pain was −3.0 ( P < 0.0001). The only patient who expected less pain than she subsequently experienced had a paraesthetic sensation. Gender, age, or previous experience from central neuraxial block did not significantly affect neither expected nor experienced pain. Conclusions Patients expect significantly more pain than they experience from receiving an epidural block. [ABSTRACT FROM AUTHOR]

This paper presents a novel concept of a millimeter-wave waveguide switch based on a microelectromechanical (MEMS)-reconfigurable surface with insertion loss and isolation very similar to high performance but bulky rotary waveguide switches, despite its thickness of only 30 \mu\m. A set of up to 1470 micromachined cantilevers arranged in vertical columns are actuated laterally by on-chip integrated MEMS comb-drive actuators, to switch between the transmissive state and the blocking state. In the blocking state, the surface is reconfigured so that the wave propagation is blocked by the cantilever columns short-circuiting the electrical field lines of the TE10 mode. A design study has been carried out identifying the performance impact of different design parameters. The RF measurements (60–70 GHz) of fabricated, fully functional prototype chips show that the devices have an isolation between 30 and 40 dB in the off state and an insertion loss between 0.4 and 1.1 dB in the on state, of which the waveguide-assembly setup alone contributes 0.3 dB. A device-level yield analysis was carried out, both by simulations and by creating artificial defects in the fabricated devices, revealing that a cantilever yield of 95% is sufficient for close-to-best performance. The actuation voltage of the active-opening/active-closing actuators is 40–44 V, depending on design, with high reproducibility of better than (\sigma=\ 0.0605 V). Lifetime measurements of the all-metal, monocrystalline-silicon core devices were carried out for 14 h, after which 4.3 million cycles were achieved without any indication of degradation. Furthermore, a MEMS-switchable waveguide iris based on the reconfigurable surface is presented. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a bandpass filter with independent center frequency and bandwidth control. It is based on four frequency-reconfigurable resonators arranged in a series cascade of a second-order bandpass filter and a dual-behavior resonator. A measured bandpass filter response with variable bandwidth between 440 and 0 MHz is demonstrated at 3.6 GHz. The center frequency of the filter can be continuously varied between 2.76 and 3.79 GHz (1.4:1) with continuous bandwidth variation between 300 and 100 MHz (3:1) for a minimum out-of-band isolation of −15 dB and insertion loss between 0.76 and 2.5 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2745-2750, 2013 [ABSTRACT FROM AUTHOR]