Maximum Phase Shift Research Articles

Head-on Collision Between Two Hydroelastic Solitary Waves in Shallow Water

A comprehensive theoretical study on the head-on collision between two solitary waves in a thin elastic plate floating on an inviscid fluid of finite depth is investigated analytically by means of a singular perturbation method. The effects of plate compression are also taken into account. The Poincare–Lighthill–Kuo method has been used to derive the solution up to the fourth order of the resulting nonlinear differential equation, which in principle gives the asymptotic series solution. It is found that after collision, both the hydroelastic solitary waves preserves their original shape and positions. However a collision does have imprints on colliding waves with non-uniform phase shift up to the third order which creates tilting in the wave profile. Maximum run-up amplitude, wave speed, phase shift and distortion profile have also been calculated and plotted for two colliding solitary waves.

Geometrical constraints for membrane polarization

ABSTRACTMembrane polarization is one process that might describe the causes of induced polarization in sediments at the pore scale. Here, we investigate the practical relevance of one particular model, which consists of two cylindrical pores with different radii r and lengths L, for which the impedance can be calculated analytically. We derive approximate equations that relate polarizabilities and relaxation times directly to r and L. Based on these relations and on a systematic exploration of the parameter space, we investigate under which conditions membrane polarization is relevant in the sense that it produces measurable phase shifts in the frequency range typically observed in the laboratory or at the field scale.In principle, a wide range of spectra can be obtained. Maximum phase shifts up to hundreds of milliradian can be simulated, and the characteristic time scales cover the entire range typically measured in the laboratory. We discuss some specific constraints in the context of results from mercury injection porosimetry and recently published laboratory data and show that the required geometries are not unrealistic, even if a moderate ratio between pore length and width is included as an additional condition. We conclude that membrane polarization as a possible mechanism is not limited to a particular frequency range. We also provide evidence that the pore length of the wide pore is likely to control the measured relaxation times in practical situations. The results encourage further attempts to combine impedances of two‐pore systems to approach the simulation of real sediments, with the aim to extract pore space parameters from measured data.

Simulation of membrane polarization of porous media with impedance networks

ABSTRACTThe spectral induced polarization method is supposed to have some potential to provide useful information on hydraulic properties of the subsurface. One difficulty for the practical implementation is the simulation of underlying physical processes at the pore scale and their upscaling to hydraulically relevant scales. We extend an existing semi‐analytical membrane polarization model to two‐ and three‐dimensional impedance networks, which are numerically solved to obtain a spectral induced polarization response that can be compared to measured data.The original model consists of two cylinders with different sizes. The model has been shown to be able to reproduce some basic features of spectral induced polarization spectra measured in the laboratory, but it is unable to meet the complexity of macroscopic porous media structures, which can be found within unconsolidated sediments or rocks. To approach realistic pore space geometry, we connect different combinations of cylinders to networks. We treat the smaller of the two cylinders as a pore throat. The pore throat distribution in the network is chosen by matching measured pore throat radii distributions obtained from the mercury injection method. The large cylinder is treated as the (large) pore body, and its radii are associated to the pore throats using existing relationships.We compare the behaviour of the networks with real porous media by using sandstone samples for which both the electrical and petrophysical properties have been measured. We adjust the geometrical parameters of the network, i.e., pore lengths, pore radii, and their relative occurrences, such that they match the measured parameters (specific internal surface area, pore throat distribution, and porosity) of the sandstone samples. The measured spectral induced polarization parameters, like the maximum phase shift and the characteristic relaxation time, are qualitatively consistent with our simulation results.

A study of the effect of different coplanar dual-coil geometries on the performance of mutual inductance

This paper studies the sensing performance of different coplanar dual-coil geometries, which affects the phase variation of mutual inductance. Five micro-coil designs, including square, circular and three rounded rectangular types, are proposed in this study. These are fabricated using a simple silicon-based micro-electroplating process. By measuring the phase variation between the excitation and sensing coils, the sensing performance of different coil designs, with the effect of eddy current, are characterized quantitatively. Commercial COMSOL software and Multisim are used to evaluate the equivalent electrical properties for each type of coil under the same specification. Analysis results show that the phase difference is dominated by mutual inductance and coupling capacitance, and the square-like coils produce a smaller phase difference. The experimental results also show that the more it approached a square-type coil, the smaller the phase difference became. Using saline concentrations from 0% to 20%, the positive phase shift for the square-type coil increased as the concentration increased to a maximum value of plus 4°. The opposite is true of circular coils, with a maximum negative phase shift of minus 5.5°. It is revealed that a specific sensing performance is easily realized by changing the coil geometry and its feature size.

All-optical phase shifter and switch near 1550nm using tungsten disulfide (WS2) deposited tapered fiber.

All-optical phase shifters and switches play an important role for various all-optical applications including all-optical signal processing, sensing and communication. In this paper, we demonstrate a fiber all-optical phase shifter using few-layer 2D material tungsten disulfide (WS2) deposited on a tapered fiber. WS2 absorbs injected 980 nm pump (control light) and generates heat, which changes the refractive index of both WS2 and tapered fiber due to thermo-optic effect and achieves a maximum phase shift of 6.1π near 1550 nm. The device has a loss of 3.7 dB. By constructing a Mach-Zehnder interferometer with WS2 based phase shifter in one arm, an all-optical switch is also obtained with an extinction ratio of 15 dB and a rise time of 7.3 ms. This all fiber low-cost and compact optical phase shifter and switch demonstrates the potential of 2D transition metal dichalcogenides for all-optical signal processing devices.

All-Printed Flexible Microwave Varactors and Phase Shifters Based on a Tunable BST/Polymer

This paper presents all-printed varactors and phase shifters using direct-ink writing methodologies on flexible organic films. The key enabler is a novel ferroelectric nanoink that allows printing high dielectric constant, low loss, and electrostatically tunable dielectrics at extremely low temperatures. The dielectric is made by suspending nanoparticles of barium strontium titanate (BST) in thermoplastic cyclic olefin copolymer (COC) to create a multiphase BST/COC nanocomposite. Unlike conventional ferroelectric ceramics, this ferroelectric dielectric requires no sintering and can be printed on any substrate. After printing, it is cured at temperatures below 200 °C. Careful stoichiometry and particle analysis of BST powders resulted in identifying conditions for achieving electrostatic tunability. A high relative permittivity of ${ \varepsilon _\text{r} = 38}$ and a very low dielectric loss of ${\tan \delta = 0.002}$ at $f= 10$ GHz were measured for the printed sinterless dielectric. The ink allows printing voltage-variable capacitors with a capacitance tunability up to 10% at microwave frequencies. The tunable capacitors were utilized in a left-handed transmission line design to create all-printed tunable phase shifters with up to a maximum phase shift of $\Delta \phi = {97}$ ° and a maximum figure of merit of 29°/dB at $f= 10$ GHz.

A Self-Aligning Cylindrical Sliding Short Plunger for Millimeter-Wave Rectangular Waveguides and Its Application in a Reflection-Type Phase Shifter

A sliding short for millimeter-wave rectangular waveguides and its dedicated application in a reflection-type phase shifter are presented. The design of the sliding short has self-aligning properties, where the correct and stable positioning of the sliding short on the central axis of a rectangular waveguide is guaranteed. Unwanted and disruptive waveguide wall contacts are avoided by design. Misalignment of the sliding short is only possible due to mechanical tolerances. This is systematically investigated by parametric full-wave simulations. Measurements of a ${W}$ -band prototype yield a return loss better than 0.1 dB for offset positions from 0 to 1.5 mm throughout the whole ${W}$ -band. A mechanical reference plane outside of the rectangular waveguide is used for correct and reproducible axial positioning of the sliding short in the waveguide. Mechanically measured offset positions and those retrieved from the reflected phase agree to a maximum error of 6 $\mu \text{m}$ , which is within the manufacturing tolerance and the measurement uncertainty. Based on the proposed self-aligning sliding short, a reflection-type phase shifter has been realized, where a branch-guide coupler with a seven-slot design is used as broadband quadrature hybrid. Measurement results indicate an insertion loss in the range of 0.2 dB from 80 to 105 GHz and a maximum phase shift of ~160° and 330° at 75 and 110 GHz, respectively.

A novel high power X-band ferrite phase shifter.

A novel high power X-band ferrite phase shifter (PS) employing the structure of several waveguides connected in parallel is proposed. Each of the waveguides is a phase shift unit utilizing a dual-toroid structure. First, the phase shift unit is designed, manufactured, and tested. The results indicate that the power capacity reaches 115 kW. At this power, the maximum magnetic field strength of ferrite is 7.9 kA/m, beyond which the nonlinear effect of ferrite will occur. On this basis, the PS that consists of four units connected in parallel is designed. According to the threshold of ferrite, the power capacity of the PS can theoretically reach 430 kW. Limited by the maximum output power of the microwave source, the preliminary high-power test results demonstrate that the PS can operate properly at 270 kW. The PS exhibits an insertion loss of 0.82 dB and a maximum differential phase shift of approximately 300° at 9.3 GHz. The return loss of the PS is more than 16 dB from 9.0 to 9.5 GHz.

Artificial high birefringence in all-dielectric gradient grating for broadband terahertz waves.

Subwavelength dielectric gratings are widely applied in the phase and polarization manipulation of light. However, the dispersion of the normal dielectric gratings is not flat while their birefringences are not enough in the THz regime. In this paper, we have fabricated two all-dielectric gratings with gradient grids in the THz regime, of which artificial birefringence is much larger than that of the equal-grid dielectric grating demonstrated by both experiments and simulations. The transmission and dispersion characteristics are also improved since the gradient grids break the periodicity of grating lattices as a chirp feature. From 0.6–1.4 THz, a broadband birefringence reaches 0.35 with a low dispersion and good linearity of phase shift, and the maximum phase shift is 1.4π. Furthermore, these gradient gratings are applied as half-wave plates and realize a linear polarization conversion with a conversion rate over 99%, also much higher than the equal-grid gratings. These gradient gratings show great advantages compared to the periodic gratings and provide a new way in the designing of artificial birefringence material.

Dynamically Reconfigurable High Impedance and Frequency Selective Metasurfaces Using Piezoelectric Actuators

Novel dynamically reconfigurable low-loss high impedance and frequency selective metasurfaces (FSmSs) are presented, operating at around 15 GHz and incorporating compact piezoelectric actuators. The high impedance metasurface (HIS) consists of an array of metallic elements printed on a thin dielectric substrate, placed over a ground plane, and supported by the actuators. Under a dc bias, the actuators produce a displacement between the two layers, resulting in a change in the reflection phase response. Furthermore, novel multilayer FSmSs are proposed achieving significant tuning of their passband response with low losses. The FSmSs consist of three closely spaced periodic arrays of subwavelength nonresonant elements, namely, an array of metallic square loops placed between two arrays of square apertures in metallic sheets, separated by air cavities. The combination of the square loop array and one of the square aperture arrays produces a high impedance surface response, which is tuned using the piezoelectric actuators. This in turn alters the resonance condition of the complete FSmS structure and thus the central frequency of the passband. The structures have been investigated through simulations and measurements with good agreement, achieving an experimental frequency tuning range of 17% for the HIS and of 8.8% for the FSmS as well as a maximum phase shift of over 177° for the HIS at approximately 14 GHz.

3-D Printed Variable Phase Shifter

This letter presents the first fully 3-D printed microwave variable phase shifter. The design methodology for a 3-D printable dielectric flap metal-pipe rectangular waveguide variable phase shifter is described. The ABS building material was independently characterized, revealing a dielectric constant of 2.34 and loss tangent of only 0.0015 at 10 GHz. The predicted and measured performance is given, demonstrating a maximum relative phase shift of 142° at 10 GHz, with a near uniform relative phase shift across the whole of X-band and a low variation in differential-phase group delay.

Modeling non-saturated ferrite-based devices: Application to twin toroid ferrite phase shifters

This article describes a new set of tools developed to improve the conception and modeling of non-saturated ferrite-based devices such as twin toroid phase shifters. These new simulation tools benefit from a generalized permeability tensor model able to describe the permeability tensor of a ferrite sample whatever its magnetization state. This model is coupled to a homemade 3D multi-scale magnetostatic analysis program, which describes the evolution of the magnetization through the definition of a hysteresis loop in every mesh cell. These computed spectra are then integrated into 3D electromagnetic simulation software that retains the spatial variations of the ferrite properties by using freshly developed macro programming functions. This new approach allows the designers to accurately model complex ferrite devices such as twin toroid phase shifters. In particular, we demonstrated a good agreement between simulated and measured phase shifts as a function of applied current values with a predicted maximum phase shift of 0.96 times the measured value.

The dependence of induced polarization on fluid salinity and pH, studied with an extended model of membrane polarization

The estimation of hydraulic parameters from spectral induced polarization (SIP) measurements is difficult partly because the electrical impedance of sediments depends on several parameters that are not related to the texture. Important parameters that influence the spectral response are fluid salinity and pH. In order to understand the behaviour of SIP spectra from a mechanistic point of view, we carry out simulations with a membrane polarization model. The geometry consists of a sequence of wide and narrow pores with finite radii. The charge distribution at the mineral surface is described by a triple layer model, characterized by the zeta potential and the partition coefficient. We extended an existing model by incorporating known dependencies of the zeta potential and the partition coefficient on fluid salinity and pH.Our simulation results predict a decrease of the maximum phase shift of the complex electrical conductivity with increasing salinity, consistent with experimental observations. For very small pore radii, the phase shift may also show the opposite behaviour and increase with salinity. The imaginary conductivity at 1Hz increases with increasing salinity, followed by a peak and a decrease at high salinities. The fact that our model predicts a decrease of the imaginary conductivity at high salinities is particularly important, because strong experimental evidence was recently found for such a decrease, which was theoretically unexplained so far.Both the maximum phase shift and the imaginary conductivity at 1Hz decrease when pH decreases. The reason is that at low pH, the zeta potential and the partition coefficient both decrease, corresponding to a smaller charge density at the mineral surface, resulting in a weaker impact of the electrical double layer. The few existing experimental studies on pH dependence are qualitatively consistent with our simulation results.

A 1.7–2.7-GHz 4-bit Phase shifter based on packaged RF MEMS switches

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.

Electrically tunable liquid crystal terahertz phase shifter driven by transparent polymer electrodes

A high performance liquid crystal terahertz phase shifter based on transparent polymer electrodes.

A Low-loss Phase Shifter with Harmonics Suppression Using Compact Hybrid Coupler

In this paper, a compact low-loss reflector-type phase shifter with harmonic suppression using meander T-shaped branch-line coupler is suggested. The compact coupler for the phase shifter has a size of while a conventional branch coupler has a size of . The phase shifter shows insertion losses of 0.19-0.28 dB at the center frequency of 2.1 GHz, and a measured maximum phase shift of .

High-Sensitivity High-Resolution Optical Phase Shift Detection Technique Using a Si Photodiode Operating in Photovoltaic Mode

In this paper, we report the optimization of the operating conditions and the maximization of the performances of the phase shift detection technique allowing to approach the best sensitivity and resolution in terms of light power variations. The system is based on the synchronous demodulation technique and uses a Si photodiode operating in photovoltaic mode biased through a small amplitude sinusoidal modulating signal. Employing a commercial lock-in amplifier for phase measurements and varying the signal modulating frequency, we prove that it is possible to obtain the maximum theoretical phase shift variation range equal to 90° with a resulting sensitivity and resolution equal to 3100°/ $\mu \text{W}$ and 3 pW, respectively. We demonstrate that these results are more than two orders of magnitude greater than those ones achievable by employing a Si photodiode in photoconductive mode. As a case-example for chemical applications, we apply the proposed technique to detect the variations of the molar concentration of a methylene blue solution by measuring the variations of the transmittance of a laser beam passing through the substance. The experimental findings are compared with those ones achieved by using a commercial spectrophotometer and the conventional amplitude detection technique employing the lock-in amplifier. Despite the achieved results are limited by the fixed phase resolution of the employed lock-in amplifier, here, the proposed approach allows to measure molar concentration variations with a resolution of 79 pM resulting 1354 times higher than that one obtained using the spectrophotometer and 33 times better than the value achieved with the amplitude detection technique.

Anomalous optical Anderson localization in mixed one dimensional photonic quasicrystals.

Anomalous optical Anderson localization (AOAL) in mixed one-dimensional (1D) photonic quasicrystals with matching impedance is obtained when the average refractive index of left- and right-handed layers is approximately zero. The transport properties of ordinary and anomalous localization are investigated and compared. The difficulties in expressing analytically the scaling factors of the mixed photonic quasicrystals are illustrated from Hamiltonian-map analysis. An approach based on transfer matrix method is proposed to simulate the localization behavior. From the simulation, it is found that the narrow distribution of the phase shift is responsible for AOAL in the mixed photonic structures. The scaling factors of AOAL decrease with the broadening of the phase shift distribution. The maximum phase shifts of the mixed photonic structures determine the lower boundary of the anomalous localization.

Contribution to the Development of a Method of Estimate Of The Time Of Concentration of the Maximum Flows of the Rain

Among the characteristics that determine the maximum throughput flood genesis, concentration time has an important place. The maximum phase shift of a flood rain is subjected to different types of river regulation. This is caused by the friction forces in the river bed, by the gradual change of the wetted area by the slope and also by the flow exchanges. The flood speed is proportional to the water level in the river bed or the corresponding flow. Keywords: Flood, maximum, concentration speed.

Exploration of photon-number entangled states using weak nonlinearities.

A method for exploring photon-number entangled states with weak nonlinearities is described. We show that it is possible to create and detect such entanglement at various scales, ranging from microscopic to macroscopic systems. In the present architecture, we suggest that the maximal phase shift induced in the process of interaction between photons is proportional to photon numbers. Also, in the absence of decoherence we analyze maximum error probability and show its feasibility with current technology.