The Effect of Windings on ADSL Transformer Insertion Losses

Insertion loss （IL） is one of the important parameters of asymmetrical digital subscriber loop （ADSL） transformers. In different frequency bands, the factors that affect insertion loss are different. Windings mainly affect insertion loss in mid and high frequency bands. The effects of winding ways, winding wire diameter and winding turns on insertion loss were discussed. The presented experiment shows that the insertion loss of an ADSL transformer could be under 0.4 dB in mid frequency band when the winding is 30 turns, in which the ADSL transformer satisfies the requirement of total harmonic distortion （THD）. Our experiments also show that the sandwich winding structure is better than the side by side winding structure and the twisted-pair winding structure, and the increase of winding diameter is one means to reduce insertion losses of an ADSL transformer in mid frequency band.

Fabrication and Numerical Simulation of a MicromachinedContact Cantilever RF-MEMS Switch

This paper reports a contact cantilever MEMS switch. The designed switch has a metal cantilever that acts as an electrostatically activated switch with processing options to achieve dielectric isolation of the controlvoltage path from the signal path. To obtain good material properties,an ANSYS FEA tool is used to optimize the structure. The RF MEMS switch is fabricated via a surface micromachining process. The switch has an actuation voltage of 12V,which is close to the simulated value of 11V. The measured and the HFSS simulated isolations are both higher than - 20dB from 0.05 to 10GHz. The measured insertion loss is less than - 0.9dB, relatively larger than the simulated loss of less than - 0.2dB from 0.05 to 10GHz. This is because a contact resistance introduced due to poor physical contact between the bottom lines and the metal cantilever.

A modulator using RF CMOS T-type attenuator for TH-UWB communications

The insertion loss （IL） of a T-type attenuator is theoretically analyzed. A T-type RF （ radio frequency） CMOS （ complementary metal-oxide-semiconductor ） attenuator is designed as an on-off keying（OOK） modulator in a time-hopping ultra wide-band （TH-UWB）communication with a carrier frequency of 4 GHz. In the topology of the OOK modulator circuit, there are three parts, an oscillator with an oscillating frequency of 4 GHz, a T-type attenuator constructed by RF CMOS transistors, and an output impedance matching network with a L-type LC structure. The modulator is controlled by a time-hopping pulse position modulation（TH-PPM） signal. The envelope of the modulated signal varies with the amplitude of the controlling signal. Meanwhile, an output matching network is also designed to match a 50 Ω load. In 0. 18 μm RF CMOS technology, a modulator is designed and simulated. The implemented modulator chip has 65 mV of the output amplitude at a 50 fl load from a 1.8 V supply, and the return loss （ S11 ） at the output port is less than - 10 dB. The chip size is 0. 7 mm × 0. 8 mm, and the power consumption is 12. 3 mW.

Railway ground vibration and mitigation measures: benchmarking of best practices

Vibration and noise aspects play a relevant role in the lifetime and comfort of urban areas and their resi-dents.Among the different sources,the one coming from the rail transit system will play a central concern in the following years due to its sustainability.Ground-borne vibration and noise assessment as well as techniques to mitigate them become key elements of the environmental impact and the global enlargement planned for the railway industry.This paper aims to describe and compare the different mitigation systems existing and reported in liter-ature through a comprehensive state of the art analysis providing the performance of each measure.First,an introduction to the ground-borne vibration and noise gen-erated from the wheel-rail contact and its propagation through the transmission path is presented.Then,the impact and the different ways of evaluating and assessing these effects are presented,and the insertion loss indicator is introduced.Next,the different mitigation measures at different levels(vehicle,track,transmission path and receiver)are discussed by describing their possible appli-cation and their efficiency in terms of insertion loss.Finally,a summary with inputs of how it is possible to address the future of mitigation systems is reported.

Acoustic Radiation of Damped Cylindrical Shell with Arbitrary Thickness in the Fluid Field

The insertion loss of acoustic radiation of damped cylindrical shell described by 3-D elasticity Navier equations under radial harmonic applied load in fluid is presented. The classical integral transform technique, potential theory and Lamè resolution are used to derive the solutions of Navier equations. The higher precision inversion computation is introduced to solve the linear equations. Comparing with acoustic radiation of one-layer cylindrical shell, the influence of thickness, mass density, dilatational wave loss factor and Young's modulus of damping material and circumferential mode number of the cylindrical shell on the insertion loss is concluded. The theoretical model in the paper can be used to deal with the arbitrary thickness and any frequency of the coated layer in dynamic problem. The conclusions may be of theoretical reference to the application of damping material to noise and vibration control of submarines and underwater pipes.

A survey of active quasi-circulators

With the development of multi-band wireless communication and the increasing data transmission rate,the circulator as an antenna interface must be able to work in multiple frequency bands and provides large bandwidth.It presents a high challenge to the design of circulators,especially the active quasi-circulators.In this survey,we review the representative active quasi-circulators and summarize three different techniques and the corresponding structures to show an incremental improvement of the isolation and bandwidth of the active quasi-circulators.In addition,we also compare the performance of several state-of-art active circulators,and analyze their advantages and disadvantages.Finally,we conclude the future trend of the active quasi-circulators.

Study of High Capacitance Ratios CPW MEMS Shunt Switches

This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch.In this switch,a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state.The area size of the metal plate directly influences the capacitance ratio of the switch,as the area size of the metal cap decreases,the capacitance ratio dramatically rises up.The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size.Measurement results show that high capacitance ratio of the switches has a large effect on the isolation,and can actually improve the performance of the switches.

Propagation and Attenuation Characteristics of Diesel Particulate Filter

Diesel particulate filter (DPF) is an important factor which influences the sound from exhaust system of an engine. In order to understand the propagation law of sound wave and predict the insertion loss in DPF, based on the general aero-dynamic equations and Darcy′s law, an acoustic property calculation model of DPF is constructed. Propagation and attenuation characteristics of the forward and backward propagating acoustic waves in the close and open pipe of the filter are investigated. The theoretical model is combined with experiment to investigate sound attenuation property of DPF. The insertion loss obtained from the experiment is compared with that computed for a DPF. The results from the experiment and theoretical calculation agree well.

Capacitive Coupled Wide-Notch Stepped Impedance Narrow-Band Bandpass Filter for WiMax Application

The development of wireless communication standards necessitates optimal filter design for the selection of appropriate bands of frequencies.In this work,a compact in size pair of parallel coupled symmetric stepped impedancebased resonator is designed with supporting to the WiMAX communication standards.The coupled resonator is tuned to allow the frequency band between 3.4 GHz and 3.8 GHz,which is centered at 3.6 GHz.A parasitic effect of capacitively coupled feed structure is used for exciting the two symmetrical stepped impedance resonators.The bandwidth and selectivity of the filter are enhanced with the change of characteristic impedances and controlling the coupling gap between resonators.This design offers single narrow sharp passband selectivity as well as multiple stopband harmonic suppression arising as a result of multiple transmission zeros.The designed filter operates with a fractional bandwidth(FBW)of 11.47%.The proposed single narrowband bandpass filter provides better suppression in either side of the tuned frequency(3.6 GHz)without degrading the passband performance.Also,this novel filter offers an insertion loss of about−0.08 dB and a return loss of greater than−30 dB in passband.This approach is useful for eliminating unwanted spurious harmonics responses that enter the desired response.The suggested bandpass filter has been simulated using Advanced Design System(ADS)tool,and the measurement has been made using a network analyzer,and the results are reported.

A DESIGN OF 0.25μm CMOS SWITCH

Single-Pole Double-Throw （SPDT） broadband switch has been designed in a 0.25gm Complementary Metal Oxide Semiconductor （CMOS） process. To optimize the performance of isolation and insertion loss, based on normal design, the effects of Gate Series Resistances （GSR） on insertion loss and switching time are analyzed for the first time. The compatible GSRs are chosen by the analyses. The fabricated chips were tested and the results show the switch isolation from DC （Direct Current） to 1GHz exhibits 55dB and insertion loss lower than 2.1 dB.

A Novel Trident Incurvature Shape DGS to Suppress Radiated Emission in High Speed Printed Circuit Board

As per the entail in wireless communication, the ever increasing switching speeds of digital devices pose significant challenges. Signal quality is more important for high speed products and the signal integrity must ensure reliable transmission where signal integrity is a measure of the quality of an electrical signal. A high speed differential signal will result in signal integrity issues such as crosstalk and radiated emission. One of the solutions to suppress radiated emission is defected ground pattern. This paper introduces a novel trident incurvature shaped defected ground structure to suppress radiated emission that arises in high speed differential signal. The proposed defected ground structure is implemented using Ansoft HFSS simulation tool and its performance is quantified in terms of scattering parameters. The proposed trident incurvature shaped defected ground pattern reduces near end coupling and far end coupling by more than 6 dB and 2 dB respectively. It also provides better return loss and insertion loss in the frequency range 1 - 6 GHz.

Graphene field effect transistor-based terahertz modulator with small operating voltage and low insertion loss

In this work, we report a broadband terahertz wave modulator based on a top-gate graphene field effect tran- sistor with polyimide as the gate dielectric on a PET substrate. The transmission of the terahertz wave is modulated by controlling the Fermi level of graphene via the polyimide as the top-gate dielectric material instead of the traditional dielectric materials. It is found that the terahertz modulator can achieve a modulation depth of ~20.9% with a small operating gate voltage of 3.5 V and a low insertion loss of 2.1 dB.

On-chip cyclic-AWG-based 12 × 12 silicon wavelength routing switches with minimized port-to-port insertion loss fluctuation

With the rapidly increasing bandwidth requirements of optical communication networks, compact and low-cost large-scale optical switches become necessary. Silicon pbotonics is a promising technology due to its small footprint, cost competitiveness, and high bandwidth density. In this paper, we demonstrate a 12 × 12 silicon wavelength routing switch employing cascaded arrayed waveguide interconnection network on a the switch＇s footprint. We single chip. We optimize develop an algorithm based gratings （AWGs） connected by a silicon waveguide the connecting strategy of the crossing structure to reduce on minimum standard deviation to minimize the port-to- port insertion loss （IL） fluctuation of the switch globally. The simulated port-to-port IL fluctuation decreases by about 3 dB compared with that of the conventional one. The average measured port-to-port IL is 13.03 dB, with a standard deviation of 0.78 dB and a fluctuation of 2.39 dB. The device can be used for wide applications in core networks and data centers.

Measurement of insertion loss for underwater acoustic passive materials with the time reversal technique

A method using the time reversal（TR） technique to measure the insertion loss（IL） of passive materials is presented.Firstly the received signals are focused according to the TR theory when there is not a sample between the source and the received array.Then,the sample is placed near the received array and the TR processing is again employed to realize the focus of the received signal.Finally,the IL of the sample is evaluated from these focusing signals.Because the TR processing can focus the energy in spatial domain and time domain,the method can be used to measure acoustic properties of passive materials in a waveguide tank with reflections induced by boundaries or with low source frequencies.Two samples with the same size of 1.1 m×1.0 m×5 mm are tested in the waveguide tank.The method is demonstrated by the comparison of the theoretical and the experimental results in the measured frequency range of 1-20 kHz.

The design of electroabsorption modulators with negative chirp and very low insertion loss

Electroabsorption modulators（EAMs） with negative chirp and very low insertion loss are numerically designed with asymmetric intra-step-barrier coupled double strained quantum wells（AICD-SQWs） based on InGaAlAs material.For this purpose,the electroabsorption coefficient is calculated over a range of wells layer strain from compressive（CS） to tensile（TS）.The chirp parameter and insertion loss for TE input light polarization are evaluated from the calculated electroabsorption spectra,and their Kramers-Kronig transformed refractive index changes.The results of the numerical simulation show that the best range of left and right wells strain for EAMs based on AICD-SQWs with negative chirp and very low insertion loss are from 0.032%to 0.05%（TS） and-0.52% to-0.50%（CS）,respectively.

An impulse technique of measuring insertion loss of open screens

An impulse response technique has been investigated by application to the open screens for obtaining sound transmission loss. The measurements of such screens according to ISO 140 were also presented. The predicted results calculated by a model which is based on Huygen's principle and Kirchhoff's formulation have shown good agreements with the results obtained by impulse method. The method requires no specialist acoustic facilities and measurement systems can be portable.

Non-blocking four-port optical router based on thermooptic silicon microrings

By using silicon-on-insulator(SOI) platform, 12 channel waveguides, and four parallel-coupling one-microring resonator routing elements, a non-blocking four-port optical router is proposed. Structure design and optimization are performed on the routing elements at 1 550 nm. At drop state with a power consumption of 0 m W, the insertion loss of the drop port is less than 1.12 d B, and the crosstalk between the two output ports is less than-28 d B; at through state with a power consumption of 22 m W, the insertion loss of the through port is less than 0.45 d B, and the crosstalk between the two output ports is below-21 d B. Routing topology and function are demonstrated for the four-port optical router. The router can work at nine non-blocking routing states using the thermo-optic(TO) effect of silicon for tuning the resonance of each switching element. Detailed characterizations are presented, including output spectrum, insertion loss, and crosstalk. According to the analysis on all the data links of the router, the insertion loss is within the range of 0.13—3.36 d B, and the crosstalk is less than-19.46 d B. The router can meet the need of large-scale optical network-on-chip(ONo C).

Design of a Polymer Directional Coupler Electro-Optic Switch with Low Push-Pull Switching Voltage at 1550nm

A polymer directional coupler （DC） electro-optic switch with push-pull electrodes and rib waveguides is designed based on the conformal transforming method, image method, coupled mode theory, and electro-optic modulation theory. Its structure and principle are described, the design and optimization are performed, and the characteristics are analyzed, including the coupling length, switching voltage, output power, insertion loss, and crosstalk. To realize normal switching function,the fabrication tolerance,wavelength shift, and coupling loss between a single mode fiber （SMF） and the waveguide are discussed. Simulation results show that the coupling length is 3082μm; the push-pull switching voltage is 2.14V;and the insertion loss and crosstalk are less than 1.14 and -30dB,respectively. The proposed analytical technique on waveguides and electrodes is proven to be accurate and computationally efficient when compared with the beam propa- gation method （BPM） and the experimental results.

Analysis of Faraday–Michelson quantum key distribution system with unbalanced attenuation

Quantum key distribution （QKD） is a major research topic because it provides unconditional security. Unfortunately, many imperfections remain in QKD＇s experimental realization. The Faraday-Michelson （FM） QKD system is proposed to eliminate these imperfections using polarization. However, the long arm＇s phase modulator （PM） has an unexpected insertion loss, meaning that the state sent is no longer perfect. In this letter, we propose an alternative FM-QKD system structure, and analyze the security and key generation rate in comparison with the original system via different analysis methods. We find an obvious key rate improvement when the PM insertion loss is not extremely small.

Several mechanically-induced long-period gratings by a grooved plate

A simple method to mechanically induce a long-period fiber grating (LPFG) by a grooved plate is improved. The transmission spectra of a grating under different pressures and other types of gratings are experimentally investigated. This method is simple and reconfigurable and offers large spectra tunability. This type of LPFG has potential applications in gain flattening in erbium-doped fiber amplifiers (EDFA) and will be of particular use in filter design.