Maximum Phase Shift Research Articles

A gap waveguide-based mechanically reconfigurable phase shifter for high-power Ku-band applications

This paper presents a novel design of a low-loss, reconfigurable broadband phase shifter based on groove gap waveguide (GGW) technology. The proposed phase shifter consists of a folded GGW and three bends with a few pins forming the GGW and one bend attached to a movable plate. This movable plate allows for adjustments to the folded waveguide length, consequently altering the phase of electromagnetic waves. The advantage of GGW technology is that it does not require electrical contact between different parts of a structure. Therefore, it enables the moving parts to slide freely without electromagnetic energy leakage, resulting in improved insertion loss in high-power applications. In addition, in the proposed design, the position of the input and output waveguide ports of the phase shifter remains fixed, which is advantageous from a practical point of view. As shown by measurement and simulation results, there is nearly 37% impedance bandwidth with the highest insertion loss of 0.6 dB, and the developed device has a maximum phase shift of 770° at the center frequency of 13 GHz. The phase shifter can be used for various radar and satellite applications that require phase control, such as beamforming networks and phased array antennas.

Practical Exploration of the 'Open or Close' Concept: Evaluation of the Hygrothermal Performance of a Bioclimatic Innovation for Onion Bulb Preservation

Substantial losses occur during the storage of onion bulbs due to the inadequacy of available preservation technologies. In an endeavor to contribute to a solution, we evaluate the thermal efficacy of a bioclimatic innovation known as the "solar cell" for onion bulb preservation. This assessment involves recording temperature data from both external and internal walls, as well as indoor and outdoor air temperatures, solar irradiation, and relative humidity levels indoors. These measurements offer insights into crucial performance parameters such as thermal phase shift, thermal inertia, thermal decoupling between internal and external environments, relative humidity, damping factor, and thermal amplitude. Furthermore, we examine the impact of external factors, including external temperature and solar radiation. Across different facades, the thermal phase shift of the chamber's structure averages between 5.5 and 10.87 hours. Notably, the maximum thermal phase shift is observed to be 11.67 hours on the Eastern wall. The lowest recorded thermal damping factor is 0.081 on the Western wall, while the highest is 0.337 on the Northern wall. The study of thermal decoupling between the internal and external environments reveals a potential temperature differential of 13.7°C and 9.5°C during the day, and-6°C at night, contingent on the time of year. Consequently, the "close or open" operational mode proves to be of significant interest. Exposed to solar radiation peaking at 1041 W/m2, the temperatures of the external facades of the walls experience a substantial increase, reaching up to 52.3°C. Meanwhile, the internal environment maintains a thermal range of 24.21°C to 31.68°C under a maximum airflow of 0.18 m/s. The average relative humidity within the storage chamber fluctuates between 42.65% and 87%. Hence, the solar cell demonstrates its capacity to create optimal conditions of 25°C-30°C and 0.062 m/s for onion bulb conservation. Nevertheless, further enhancements are warranted for effective humidity control.

Optimizing wall structure for enhanced thermal performance: A layer-specific dimensionless parameter analysis in multi-layer walls

Enhancing building energy efficiency and thermal comfort crucially involves optimizing the phase shift (PS) and decrement factor (DF) of exterior walls. Using the auxiliary function method, this paper presents analytical solutions for the DF and PS in double-layer walls, subsequently extending these to multi-layer walls. Insulation and structural material properties (density, thermal conductivity, specific heat capacity), thickness, internal and external convective heat transfer coefficients, outdoor temperature fluctuations, and insulation layering in multi-layered walls were taken into consideration in acquiring analytical solutions. Our findings in double-layer walls and analogous structures show that the DF and PS are largely governed by two dimensionless parameters per layer: thermal diffusivity index and Biot number. Regardless of Biot numbers (ε1 and ε2), an increase in thermal diffusivity indexes (δ1 and δ2) consistently reduces the DF and enhances the PS. Moreover, a larger ε1 with a smaller ε2 generally associates with a lower DF, but their impact on PS is less significant compared to thermal diffusivity index. In multi-layer walls, especially with mirror symmetry, we observe a dual extremum phenomenon, marked by prolonged PS and reduced DF. This underlines the importance of structural configuration in wall thermal performance. Thus, in double-layer structures, while the DF decreases and PS increases with increasing thermal diffusivity index, the influence of Biot numbers is comparatively minimal, highlighting the paramount role of thermal diffusivity index in optimizing thermal behavior. This discovery provides valuable guidance for identifying wall structures with minimal DF and maximal PS during the architectural design phase.

Flexible terahertz phase shifter for optically controlled polydimethylsiloxane-vanadium dioxide composite film

In the terahertz (THz) band, modulation research has become a focal point, with precise control of the phase shift of THz waves playing a pivotal role. In this study, we investigate the optical control of THz phase shift modulation in a polydimethylsiloxane (PDMS)-vanadium dioxide (VO2) flexible material using THz time-domain spectroscopy. Under the influence of an 808-nm continuous wave (CW) laser with power densities ranging from 0 to 2.74 W/cm2, the PDMS-VO2 flexible material exhibits significant phase shift modulation in the frequency range of 0.2 to 1.0 THz. The maximum optical-pumping phase shift reaches 0.27π rad at 1.0 THz in a composite material with a VO2 mass fraction of 5% and a thickness of 360 µm, and the amplitude transmittance from 0.2 THz to 1.0 THz exceeds 70%. Furthermore, the composite material exhibits good stability under at least 640 switching cycle times, as confirmed through repeatability tests. The proposed composite devices offer a new approach for more flexible phase shift modulation owing to the flexibility of the composite material and the non-contact and precise modulation of light control. Additionally, the stress-adjustable characteristics of flexible materials make them highly suitable for use in wearable THz modulators, highlighting their significant application potential.

Coherent manipulation of Brewster angles and phase shifts for both left right circularly polarized beams in chiral medium

The Brewster angles and phase shift of both left right circular polarization beams of the probe field is controlled and modified in this manuscript. Subluminal and superluminal propagation of light having group indices of ±200 has been reported. The group velocities of left circularly polarized (LCP) and right circularly polarized (RCP) beam varies to ±1.5×106 m/s while, delay times varies to ±5ns. The peak values of Brewster angles of LCP and RCP beams are calculated 0.786 radian. The maximum value phase shift of LCP and RCP is reported to 31.45 radian at length L=5λ. Strong oscillation in Brewster angles and phase variations of LCP and RCP beams are investigated with azimuthal quantum number of control field and increasing length of position coordinates. The modified results of this manuscript are useful for interferometry and lasers technology.

Novel study of inertial forces on MHD peristaltically driven micropolar fluid through porous-saturated asymmetric channel: Finite Galerkin approach

This focused study investigates the peristaltic motion of a micropolar fluid within an uneven channel filled with a porous medium, incorporating an orthogonal magnetic field to the flow. This research diverges from the traditional assumptions of lubrication theory. The governing equations, encompassing the physical characteristics of micropolar fluid peristalsis, are transformed into nonlinear coupled partial differential equations. These equations are solved using the finite element method, considering inertial effects, such as non-zero wave and Reynolds numbers. This study delves into the influence of various crucial parameters on axial velocity, pressure gradient, microrotation, and stream function, presenting graphical representations. Notably, the incremental phase shift causes an intermingling of upper and lower streamlines within both halves of the channel. As the Reynolds number increases, there is an observed reduction in bolus size, particularly at maximum phase shifts, with a tendency to move toward the central region. An increase in Hartmann number leads the bolus formation to vanish in both channels, reduces microrotation, and leads to increased pressure. Vorticity lines intensify and incline toward the peristaltic walls. An increase in the permeability parameter amplifies velocity, microrotation, volume, and bolus formation regardless of phase differences while countering pressure elevation per wavelength. Reduced concavity is observed as vorticity lines disperse across the entire area.

Dynamics of high-power coupled nonlinear oscillator arrays for electronic beam steering technique: case of the triode based van der Pol oscillator

This paper presents the dynamics of coupled nonlinear oscillator arrays (CNOAs) as phase shifter for electronic beam steering technique. The proposed phase shifter uses oscillators of van der Pol type with a fifth-order nonlinear resistance and is built on the two architectures based injection-locked oscillator array (ILOAs) and coupled oscillator arrays (COAs). The dynamics equations of the phase shifter are proposed in the frequency and time domain. With the help of mathematical tools such as bifurcation diagrams, maximum Lyapunov exponent and Hilbert transform, important cartography of different oscillating states is deduced over large range of system parameters. Different behavior of the CNOAs including chaos, 2D-torus, multistability, locked and unlocked states are depicted. The phase shift between output voltages of each pair of coupled oscillators is presented for both architectures. A detailed analysis of locked states shows that the required phase shift is synthesized by slightly varying the frequency of the injected signal, or simply by detuning the free-running frequencies of the edge oscillators in equal but opposite directions. The proposed circuit of the phased shifter is built using the original van der Pol oscillator based on a vacuum triode. The maximal phase shift reaches 63° and 75° respectively for ILOAs and COAs. With the presence of triode in the circuit, the output voltage of each oscillating element in the array reaches 100V around 60KHz and is boosted by increasing the value of the triode bias potential to more than 420V. This, therefore, increases the total power dissipation of a single oscillator in the array to more than 47dB ( 50.12W ). This circuit is a candidate for high-power electronics beam steering at ultrasonic frequency.

A liquid crystal-based multi-bit terahertz reconfigurable intelligent surface

Recently, the growing interest in reconfigurable intelligent surface (RIS) technology has spurred extensive research on its utilization in the terahertz (THz) regime. The reconfiguration of the THz field empowered by the RIS holds great significance for various practical RIS-aided implementations at THz frequencies. In this study, we present a multi-bit liquid crystal-based RIS that allows for the programmable control of THz waves. The proposed RIS is characterized by an achievable 3-bit working state as well as a near 270° maximum phase shift around 0.28 THz. This high degree of freedom in manipulating the phase of the reflected field provides flexibility in terahertz spatial beam reconfigurations. We show that the terahertz single-beam pattern can be steered continuously from 5° to 55° toward the desired angles while also allowing the adjustment of the beam number and beamwidth. Through this demonstration, we aim to contribute to the advancement of RIS technologies in the terahertz regime, paving the way for various RIS-aided applications such as THz wireless communications and beyond.

Graphene metamaterial-based broadband/dual-narrowband switchable terahertz absorber with adjustable absorptivity and large phase shift

We present a graphene metamaterial-based broadband/dual-narrowband switchable terahertz (THz) absorber with adjustable absorptivity and large phase shift. From top to bottom of the device, there are graphene-metal hybrid pattern, silicon dioxide layer, silicon layer and metal substrate. When the Fermi energy (EF) of graphene is equal to 0 eV, it has two narrowband absorption peaks at frequencies of 1.88 THz and 2.54 THz, respectively. However, when the EF is equal to 0.8 eV, it turns to a broadband absorber in the frequency range from 1.60 to 2.42 THz. Moreover, if the EF increases from 0.2 eV to 0.8 eV, its absorptivity can be dynamically adjusted from 60% to more than 90% in a broadband of 0.82 THz. Most importantly, the absorber can also dynamically control the phase shift. In the frequency range of 2.04 THz to 2.34 THz, a maximum dynamic phase shift of 192 degrees is achieved by changing the EF of graphene. This work provides an alternative method for constructing multifunctional integrated THz devices based on graphene metamaterial.

All-fiber all-optical phase controller based on F-P interferometer and Er/Yb co-doped fiber

All-optical devices have attracted much attention for its potential applications in optical communication. In this letter, we propose an all-fiber all-optical phase controller based on an active Fabry-Perot interferometer (FPI) with Er/Yb co-doped fiber (EYDF). Two sections of EYDFs generate a large amount of heat under the pumping excitation of 973 nm, and achieve refractive index change and phase shift of F-P cavity via the thermo-optic effect. Experimental results show that the maximum phase shift of fabricated device is 2.53 π with a slope of 0.0167 π/mW, as well as the phase shift can be converted into the variations of light intensity by the interference characteristic of FPI, enabling optical switching with a rise time of 221 ms. The design of all optical fiber without material coating makes the device has advantages of simple manufacturing, small footprint, especially with good long-term environmental stability. We believe this scheme may provide a new platform for the investigation of all-fiber all-optical modulation, with potential applications in the field of tunable optical filters and Q-switched lasers.

Mechanically Controlled, Wide-Angle Scanning, Series-Fed Antenna Array With Low Profile for High-Power Radar Systems

This paper presents the design and implementation of a mechanically-controlled, series-fed antenna array featuring wide-angle beamsteering at the X-band. A theoretical model of a series-fed array, including phase shifters inserted between consecutive elements, is initially developed to derive design rules and gain insight into crucial performance trade-offs. Subsequently, a mechanically-controlled, reflection-type phase shifter consisting of a branch line coupler and two Pi-network reflective loads is presented. A movable metallic overlay tunes the impedance of the reflective loads, thus effectively modifying the output phase. While requiring a minimal linear displacement of only 0.06λ0, this topology provides a maximum phase shift of 300° with an average insertion loss of 1 dB and is exploited for synthesizing a series-fed patch array. Based on simulations and measurements, the proposed antenna offers an almost constant realized gain of about 15 dBi within a wide scanning range of ±50°, and the side lobe level is better than -12 dB. The average total efficiency is 50%, and the cross-polarization levels are at least 11 dB below the maximum realized gain. The main weaknesses are the narrow bandwidth of 2.5% and the slight beam squint as the frequency varies. The proposed design is ideal for radars due to its excellent performance and high power-handling capability.

Coherent imaging with low-energy electrons, quantitative analysis

Low-energy electrons (20–300eV) hold the promise for low-dose, non-destructive, high-resolution imaging, but at the price of challenging data analysis. This study provides theoretical considerations and models for the quantitative analysis of experimental data observed in low-energy electron transmission microscopy and in-line holography. The scattering of low-energy electrons and the imaging parameters, such as the inelastic mean free path, point spread function, depth of focus, and resolution, are quantitatively described. It is shown that unlike high-energy electrons (20–300 keV), low-energy electrons (20–300eV) introduce a large phase shift into the probing electron waves. Using the projected potentials formalism, the maximal phase shift acquired by a 120eV electron wave scattered by a carbon atom is theoretically estimated to be 5.03 radian and experimentally measured to be between 3 and 7.5 radian. The point spread function evaluated for low-energy electrons shows that they diffract much stronger than high-energy electrons, and that only very thin objects of up to 3Å in thickness can be imaged in focus. Thus, when imaging an object of finite thickness, such as a macromolecule, the obtained image will always be blurred due to the out-of-focus signal. This can provide an explanation for a long-standing problem of limited resolution in low-energy electron holography of macromolecules. As for imaging of a macromolecule’s structure, it is shown that the amplitude of the wavefront reconstructed from the sample’s hologram provides the best match to the projected potential distribution of the macromolecule. To evaluate the absorption properties, the inelastic mean free path (IMFP) is considered. The IMFP values calculated from theoretical models agree with the measured values. The IMFP of about 5Å was measured by transmission through graphene of 50–200eV electrons. This result implies that the internal structure of only very thin samples can be imaged in transmission mode. A simple method to quantitatively evaluate the absorption of a specimen from its in-line hologram without the need to reconstruct the hologram is presented.

A Single-Event-Hardened Scheme for Ring Oscillator Applied to Radiation-Resistant PLL Microsystems

A voltage-controlled oscillator (VCO) is one of the key modules of the phase-locked loop (PLL) microsystem, and it is easy to bombard using high-energy particles in a radiation environment, resulting in the single-event effect. In order to improve the anti-radiation ability of the PLL microsystems used in the aerospace environment, a new voltage-controlled oscillator hardened circuit is proposed in this work. The circuit consists of delay cells with an unbiased differential series voltage switch logic structure with a tail current transistor. By reducing sensitive nodes and using the positive feedback of the loop, the recovery process of the VCO circuit to the single-event transient (SET) is reduced and accelerated, so as to reduce the sensitivity of the circuit to the single-event effect. The simulation results based on the SMIC 130 nm complementary metal–oxide–semiconductor (CMOS) process show that the maximum phase shift difference of the PLL with the hardened VCO is reduced by 53.5%, which shows that the hardened VCO structure can reduce the sensitivity of the PLL to the SET and improve the reliability of the PLL in the radiation environment.

Effects of boundary conditions on phase shift of a dual-tube conveying fluid in the Coriolis mass flowmeter

This paper investigates the effects of boundary conditions on the performance of a Coriolis mass flowmeter with double straight tubes conveying fluid. The non-self-adjoint governing equations of motion are derived in dimensionless form, and the Galerkin method is used to discretize them into a set of ordinary differential equations. The free vibration analysis of the structure, including extraction of the natural frequencies and the symmetric and antisymmetric mode shapes of double tubes, is presented. In addition, the effects of the stiffness of the elastic supports on the phase shift induced between specific points of the tubes are investigated. The greater the phase shift between two special points, the easier it will be to measure by pickoffs; consequently, and the Coriolis flowmeter will be more accurate. The results revealed that the phase shift approaches zero for small translational stiffness but approaches a limited non-zero value when the rotational stiffness approaches zero. The maximum phase shift is obtained for a specific translational and rotational stiffness. The effects of the springs’ stiffness on the stability of the tubes are also investigated.

Tungsten trioxide integrated all-fiber phase shifter

This work proposes an all-fiber phase shifter based on tapered optical fiber spin coated with tungsten trioxide (WO3). Different WO3 coating thickness was tested by varying the spin coating time from 30 to 150 s at constant 1000 rpm. Evanescent field induced by the non-adiabatic taper generated thermal optic effect through interaction with the WO3 layer, which changed its refractive index and produced phase shifting effect. The optimum spin coating time of 120 s yielded maximum phase shift of 2.52 π with wavelength shift coefficient of 0.0859 nm/mW as 980 nm pump power was varied up to 220 mW. Integration of phase shifter in fiber laser cavity produced wavelength tuning with shift coefficient of about 0.06 nm/mW. This work presents a feasible all-fiber phase shifter with simple fabrication and operation that suits current need in communication field.

Accurate modelling of nematic liquid crystal based inverted microstrip phase shifter

ABSTRACT In this paper, an accurate numerical modelling of nematic liquid crystal for the inverted microstrip phase shifter is presented. Four kinds of liquid crystal with different values of anisotropy have been studied using the conventional simplified liquid crystal model where the liquid crystal is usually assumed isotropic and homogeneous. The S parameters of the phase shifter based on these liquid crystals are simulated. Moreover, considering the anisotropy and inhomogeneous of liquid crystal, the accurate modelling of nematic liquid crystal BL006 applied in the phase shifter under the voltage is calculated. The distribution of the director and permittivity of liquid crystal at the steady state under different voltages is obtained. Based on the accurate modelling results of liquid crystal BL006, the phase shifter is remodelled and simulated. Compared with that of the simplified model, the maximum differential phase shift of the phase shifter based on the liquid crystal BL006 in the accurate model at the centre frequency of 20 GHz was reduced by about , and this error will increase with the increasing of the frequency. This numerical modelling method of liquid crystal also can be used in the design of other microwave devices based on nematic liquid crystal.

Match Zehnder interferometry and Laguerre–Gaussian fields dependent photon drag in atomic medium

The absorption, dispersion and transmission are controlled and modified with the intensities of Laguerre–Gaussian control fields in a four level cesium atomic medium. The normal and anomalous slope of dispersion are investigated for subluminal and superluminal propagation. The maximum measured value of positive/negative group index is n g =±1×107, at which, the group velocity is ±30 ms−1. The maximum delay time between the two beams at the detector without dragging is 0.414 ns and in the presence of dragging is measured to 0.44 ns. The fractional change in delay time without and in the presence of dragging Δt F is measured to ±2%. The maximum phase shift without dragging is reported to 2.6 micro radian and in the presence of dragging is investigated to ±4 micro radian. The fractional change in phase shift is reported from −200% to 50% and may be used for gravitational waves detection and other signals identification.

Phase Shifting Enhancement of a Substrate-Integrated Waveguide Phase Shifter Based on Liquid Crystal

A novel technique to enhance the phase shifting range of a liquid crystal (LC)-based, substrate-integrated waveguide (SIW) phase shifter by inserting inductive posts (IPs) is presented for the first time. The IPs inserted in the LC-based SIW phase shifter produce a phase advance based on the relative permittivity of the LC, resulting in an additional differential phase shift. At 28 GHz, the proposed structure with IPs achieves a ratio of maximum differential phase shift (∆ϕmax) to maximum insertion loss (ILmax) (FoM1) = 52.82 °/dB and ratio of maximum differential phase shift to length (FoM2) = 2.62 °/mm. Compared with conventional LC-based SIW phase shifters that lack an IP and use the same amount of LC, the FoM1 increased by 16% and the FoM2 increased by 55%. In addition, compared to the typical structure that uses additional LCs instead of IPs, the FoM1 decreased by 7%, and FoM2 increased by 21%. Therefore, inserting IPs into the LC-based SIW phase shifter can reduce the dimensions of the phase shifter and the amount of LCs required to achieve the desired differential phase shift. We believe this work can contribute to the design of compact and efficient SIW phase shifters for future telecommunication systems.

Programmable freeform optics with extended white light sources: possibilities and limitations.

Freeform optics can be used in lighting applications to generate accurate prescribed illumination patterns from compact light sources such as LEDs. When targeting dynamic illumination systems, a time-variable optical functionality is needed. Phase-only spatial light modulators (SLMs) have been used in the past for various dynamic beam shaping applications with monochromatic, zero-étendue illumination under paraxial conditions. Such limitations can no longer hold when considering lighting applications. In this paper, a novel algorithm for the calculation of smooth phase shift patterns is presented in order to generate arbitrary target patterns from arbitrary incident wave fronts for non-paraxial conditions. When applying such phase shift patterns to SLMs, these devices can be considered as programmable freeform optics. The experimental performance of the calculated phase patterns is analyzed on a real SLM, with a maximal phase shift of 6π, for collimated laser beams and white LEDs. The possibilities and limitations of generating accurate prescribed target patterns are critically discussed in terms of the angular extent of the target pattern, the consider spectrum of the light source and the étendue of the incident light beam.

Hygrothermal Study of a House Made of Local Biosourced Materials Based on Clay: Experimental Study

The purpose of this study is to experimentally analyze the thermal behavior of the walls of a prototype experimental house. A Datalogger and thermocouples were used on the experimental house to determine the temperatures of the exterior and interior walls. Also, “MSR” type HygroPuce was used to determine the exterior and interior temperatures and relative humidity of the habitat. The results show that a wall made of bio-based materials with a mixture of “earth + Hibiscus cannabinus L. fibers” allows reducing the fluctuations of the interior temperatures. We observe the peaks of temperatures on the external walls at 11:00 am and for the interior walls, the peaks are observed at 5:00 pm. The maximum thermal phase shift between the peaks of the external and internal temperatures is about 7.5 hours, and the maximum damping factor is 0.9. Also, we note that the thermal performance of the material used in the design of the envelope of the house is determined by the improvement of the response of the envelope in front of the external thermal solicitations.