Transmission Phase Shift Research Articles

Probing Micro-Newton Forces on Solid/Liquid/Gas Interfaces Using Transmission Phase Shift.

Many of the nature and life systems are driven by capillary interactions on solid/liquid/gas interfaces. Here, we present a profilometry technique called transmission phase shift for visualizing the liquid/gas interfaces in three dimensions with high resolution. Using this approach, we probe the change in tiny forces with particle radius at a solid/liquid/gas interface. We provide the first direct evidence that in the issues of floating versus sinking at small-scale, Archimedes' principle should be generalized to include the crucial role of surface tension and reveal the dominant regimes of floating particles based on the Bond number. Remarkably, the measured forces are in the range of micro-Newtons, suggesting that this terse methodology may guide the future design of a liquid microbalance and will be a universal tool for investigating capillarity and interface issues.

A wideband and low‐profile transmitarray antenna using different types of unit‐cells

AbstractA wideband low‐profile transmitarray antenna has been designed. Several prototypes of unit‐cells with different transmission phase shift ranges are used to constitute the antenna. To achieve wideband performance, the transmission phase versus frequency curves of these unit‐cell prototypes are required to be nearly parallel in the working frequency band. Also, two or more unit‐cell prototypes instead of a uniform prototype are used to avoid introducing air gaps and reduce the thickness of transmitarray, which is commonly used in transmitarray design. A wideband millimeter wave dual‐polarized transmitarray with a thickness of only 0.12λ0 is designed, fabricated, and measured. It is demonstrated that the antenna has a wide 1‐dB gain bandwidth of 20.2% (31‐38 GHz), a gain higher than 31.4 dBi, and a peak aperture efficiency of 41.3%. Good agreement between simulations and measurement is achieved.

A Dual Parameter Synchronous Monitoring System of Brain Edema Based on the Reflection and Transmission Characteristics of Two-Port Test Network

As a common secondary disease, edema after traumatic brain injury (TBI) can increase brain volume, resulting in elevated intracranial pressure (ICP), brain shift, and cerebral hernia, and can eventually lead to death. The real-time continuous monitoring of edema may significantly reduce mortality and disability. In this paper, a dual-parameter synchronous monitoring system of edema based on the reflection and transmission characteristics of the two-port test network was established; 15 rabbits were chosen to perform 24-h reflection phase shift (RPS) and transmission phase shift (TPS) simultaneously monitoring the experiments of brain edema. With the development of brain edema, the variation law of the RPS and TPS was investigated. Combined with the power amplitude spectrum and the principle of the two-port test network, the influence of frequency on the detection sensitivity of RPS and TPS was analyzed in detail, and the optimal detection frequency point was found. After that, the classification of three different degrees of edema is performed by the BP algorithm. In the animal experiment, the RPS showed a continuous increasing trend within time, and it presented the variation of (9.35910° ± 1.65702°), (12.60117° ± 2.30218°), and (16.33423° ± 2.11118°) after 6, 12, and 24 h, respectively. Meanwhile, the TPS showed a continuous downward trend with the variation of (-12.62555° ± 0.99441°), (-19.23976° ± 1.27488°), and (-27.26285° ± 2.62291°) after 6, 12, and 24 h, respectively. The RPS was negatively correlated with the TPS. The RPS and the TPS together as a recognition feature can achieve 100% accurate classification of three different brain edema severities. Based on these results, it can be concluded that the system established in this paper can monitor gradual increases in brain edema severity. Furthermore, neither the RPS nor the TPS can be set as the recognition feature alone to achieve the completely accurate classification, which shows the necessity of presenting two parameters in the monitoring process.

Dual‐polarized planar lens antenna designed with a quad‐ridged frequency selective surface

AbstractThis letter presents a microwave planar lens illuminated by a radially corrugated horn antenna. The lens is formed by a set of 5×5 multilevel unit cells working as a frequency selective surface. Each layer of the unit cells is formed by a square metallic ring with two sets of orthogonal stubs. The length of each set of stubs controls the transmission phase shift for each polarization, so that the lens can be configured independently for two orthogonal polarizations. The lens presented in this letter makes use of this operation to compensate the phase profile of the radiation pattern generated by the feeder. A prototype, with the lens located at 0.59 λ from the feeder, has been fabricated. Measured results show a maximum gain above 14.44 dBi within the operating frequency band (12.55‐13.10 GHz), and a crosspolar level below −32 dB within the HPBW.

Comments on Dual-Band Design Theory for Dual Transmission-Line Transformer

In the above paper [1] , Wang et al. proposed a dual-band parallel transmission line (TL), real-to-real impedance matching network (RRIMN). However, the possible solutions discussed in [1, eqs. (11)–(18)] are incomplete. The incompleteness is due to the selection of the positive-definite region of impedances $Z_{1}$ and $Z_{2}$ . The positive-definite region of impedances $Z_{1}$ and $Z_{2}$ in [1] are chosen as $\theta _{1}$ in the first coordinate and $\theta _{2}$ in the second coordinate. However, there exist several positive-definite regions of $Z_{1}$ and $Z_{2}$ . Hence, selecting one positive-definite region will lead to a limited solution. Here, we will provide two different possible solutions and their physical significance in terms of transmission phase shift [2] .

Thermally controlled femtosecond pulse shaping using metasurface based optical filters

AbstractShaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP) band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse’s spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

Corrections to “Theory on Matching Network in Viewpoint of Transmission Phase Shift [Jun 16 1704-1716

Presents corrections to the paper, “Theory on matching network in viewpoint of transmission phase shift,”(Sinha, R. and De, A.), IEEE Trans. Microw. Theory Techn., vol. 64, no. 6, pp. 1704–1716, Jun. 2016.

МОДЕЛИРОВАНИЕ ПРОЦЕССА ИЗМЕРЕНИЯ ПОЛОЖЕНИЯ ГРАНИЦЫ РАЗДЕЛА ДВУХ СРЕД В ЕМКОСТИ С ПРИМЕНЕНИЕМ РАДИОЧАСТОТНОГО МЕТОДА

The article describes modeling of the process for measurement of interface position between two media, in particular two immiscible liquids with different density, one over the other, contained in a tank using radiofrequency method. In this case it is provided invariance of measurement results to electrical parameters of both media. Independent sections of transmission lines with end horizontal sections are used as sensors. To provide invariance to electrical parameters of the lower medium there are used natural resonance frequencies of the two sections of a transmission line or phase shifts of electromagnetic waves with fixed frequency excited and received at the section inputs and reflected from section ends. Functional conversion of informative parameters helps to determine interface position between two media in the tank. In the modeled measurement process in order to provide invariance to electrical parameters of two liquids there are placed vertically three sections of a coaxial or two-wire transmission line. Due to the availability of horizontal end sections at all three transmission line sections, there is no uncertainty of measurement results when measuring the interface position at its zero-, or close to zero, readings in the course of functional processing of resonance frequencies of the three transmission line sections. These sections may be done identical with equal end horizontal parts of a fixed length but with different reactive loads at the ends of horizontal parts. Between parallel outer conductors of coaxial line sections up to the ends of their horizontal parts, electromagnetic oscillations are excited as in a two-conductor line section having end reactive load that is different from the end reactive loads of coaxial line sections. This provides the difference of three dependencies of corresponding resonance frequencies on coordinate of interface position between two media. Determination of interface position in the modeled measurement process on the base of this method is characterized by higher measurement accuracy, easy realization of radiofrequency devices and is free from shortcomings of other radiofrequency methods.

Pump-and-probe optical transmission phase shift as a quantitative probe of the Bogoliubov dispersion relation in a nonlinear channel waveguide

We theoretically investigate the dispersion relation of small-amplitude optical waves superimposing upon a beam of polarized monochromatic light propagating along a single-mode channel waveguide characterized by an instantaneous and spatially local Kerr nonlinearity. These small luminous fluctuations propagate along the waveguide as Bogoliubov elementary excitations on top of a one-dimensional dilute Bose quantum fluid evolve in time. They consequently display a strongly renormalized dispersion law, of Bogoliubov type. Analytical and numerical results are found in both the absence and the presence of one- and two-photon losses. Silicon and silicon-nitride waveguides are used as examples. We finally propose an experiment to measure this Bogoliubov dispersion relation, based on a stimulated four-wave mixing and interference spectroscopy techniques.

Wideband Measurement of the Phase Deviation and Time-Domain Response of an Open Fire

This letter presents an extension of the free-space method for the dielectric characterization of Eucalypt litter fire using the measured transmission phase shift of a propagating signal over a frequency range of 5–40 GHz. This method is especially suitable for a broadband, routine, nonintrusive, and accurate evaluation of fire dielectric properties from the measured transmission coefficient ( ${S}_{21}$ ). A 72 cm $\times $ 47 cm rectangular brick burning area prepared with Eucalypt ground litter was equipped with four K-type thermocouples at different heights to measure flame temperatures, which ranged from 283–865 K. The measured phase shift of an electromagnetic signal transmitted through the Eucalypt fire varied from 12.2 to −166.7° at 5.35 and 39.74 GHz. From this phase shift, the calculated real part of the relative permittivity of the fire was between 0.877 and 1, with the imaginary part from 0.02 to 0.09. The relative permittivity of less than unity confirms the formation of plasma in the combustion zone of fire, and shows good agreement with previous research. However, in this letter, the combustion zone region is defined with significantly higher accuracy, and characteristics are evaluated over a much broader frequency range. The extracted parameters are important for understanding of the reaction of electromagnetic waves in wildfire environments and can be used to design radar systems for forest fire detection.

Freestanding transparent terahertz half-wave plate using subwavelength cut-wire pairs.

We designed a cut-wire-pair metasurface that works as a transparent terahertz half-wave plate, by matching the electric and magnetic resonances of the structure. Due to the impedance matching nature of the resonances, a large transmission phase shift between the orthogonal polarizations was achieved, while permitting a high transmission. The electric and magnetic responses of the proposed structure were confirmed by evaluating the electric admittance and magnetic impedance. The structure was fabricated on a flexible film and its helicity-conversion function in the terahertz frequency range was experimentally demonstrated. The thickness of the device is less than 1/10 of the working vacuum wavelength, and a high amplitude helicity conversion rate over 80 % was achieved. Finally, using simulations, we demonstrate the feasibility of the gradually rotating cut-wire-pair array in terahertz wave-front control.

Dynamic Control of Double Plasmon-Induced Transparencies in Aperture-Coupled Waveguide-Cavity System

A theoretical model, for dynamic control of double plasmon-induced transparencies in aperture-coupled metal-dielectric-metal (MDM) waveguide-cavity system, is proposed. Based on the theoretical and numerical results, the formation and evolution mechanisms of double plasmon-induced transparencies are investigated more accurately compared to previous works. The symmetries, positions and measured full width at half maximum (FWHM) of the double transparent windows, and the transmission phase shift can be tuned freely by structural parameters. Moreover, the slot cavity location relative to aperture affects the phase difference between the left and right slot cavities to aperture center and determines the wavelength of resonance mode in aperture-side-coupled slot cavity, which plays an important role in the appearance or disappearance of transparent windows. In particular, supported by the consistency between the theoretical analysis and simulations, we obtain the threshold of coupling distance between two apertures, at which the abrupt phase shift happens. The detailed analysis may open up the possibility for precise control of light in highly integrated optical circuits.

Teleportation-based quantum information processing with Majorana zero modes

We present a new measurement-based scheme for performing braiding operations on Majorana zero modes and for detecting their non-Abelian statistics without moving or hybridizing them. In our scheme, the topological qubit encoded in any pair of well-separated Majorana zero modes in a mesoscopic superconductor island is read out from the transmission phase shift in electron teleportation through the island in the Coulomb blockade regime. We propose experimental setups to measure the teleportation phase shift via conductance in an electron interferometer or persistent current in a closed loop.

Low-temperature behavior of transmission phase shift across a Kondo correlated quantum dot

We study the transmission phase shift across a Kondo correlated quantum dot in a GaAs heterostructure at temperatures below the Kondo temperature ($T < T_{\rm K}$), where the phase shift is expected to show a plateau at $\pi/2$ for an ideal Kondo singlet ground state. Our device is tuned such that the ratio $\Gamma/U$ of level width $\Gamma$ to charging energy $U$ is quite large ($\lesssim 0.5$ rather than $\ll 1$). This situation is commonly used in GaAs quantum dots to ensure Kondo temperatures large enough ($\simeq 100$ mK here) to be experimentally accessible; however it also implies that charge fluctuations are more pronounced than typically assumed in theoretical studies focusing on the regime $\Gamma/U \ll 1$ needed to ensure a well-defined local moment. Our measured phase evolves monotonically by $\pi$ across the two Coulomb peaks, but without being locked at $\pi/2$ in the Kondo valley for $T \ll T_{\rm K}$, due to a significant influence of large $\Gamma/U$. Only when $\Gamma/U$ is reduced sufficiently does the phase start to be locked around $\pi/2$ and develops into a plateau at $\pi/2$. Our observations are consistent with numerical renormalization group calculations, and can be understood as a direct consequence of the Friedel sum rule that relates the transmission phase shift to the local occupancy of the dot, and thermal average of a transmission coefficient through a resonance level near the Fermi energy.

Theory on Matching Network in Viewpoint of Transmission Phase Shift

In this paper, the concept of the transmission phase shift of an impendance-matching network (IMN) has been introduced. The generalized two-port network parameters of the matching circuit, which matches an arbitrary complex load to a different complex source impedance incorporating the transmission phase, has been derived. In general, the IMNs are electrically asymmetric; however, there exist only two distinct values of phase shifts (180° apart) for a given source and load impedance for which the networks are symmetric, irrespective of the choice of design topology. Simple examples of symmetric matching networks like single and parallel transmission lines (TLs) have been studied. The design equations of several asymmetric matching networks like the stepped-impedance, the $\Pi $ -type, and the T-type network for a given load and source impedance with desired phase shift have been derived. The concepts of allowed and forbidden regions for such matching circuits, in the impedance phase-shift plane, have been established. Two prototype impedance transformers have been fabricated and measured to establish the proposed concept.

Measurement of the transmission phase of an electron in a quantum two-path interferometer

A quantum two-path interferometer allows for direct measurement of the transmission phase shift of an electron, providing useful information on coherent scattering problems. In mesoscopic systems, however, the two-path interference is easily smeared by contributions from other paths, and this makes it difficult to observe the true transmission phase shift. To eliminate this problem, multi-terminal Aharonov-Bohm (AB) interferometers have been used to derive the phase shift by assuming that the relative phase shift of the electrons between the two paths is simply obtained when a smooth shift of the AB oscillations is observed. Nevertheless, the phase shifts using such a criterion have sometimes been inconsistent with theory. On the other hand, we have used an AB ring contacted to tunnel-coupled wires and acquired the phase shift consistent with theory when the two output currents through the coupled wires oscillate with well-defined anti-phase. Here, we investigate thoroughly these two criteria used to ensure a reliable phase measurement, the anti-phase relation of the two output currents, and the smooth phase shift in the AB oscillation. We confirm that the well-defined anti-phase relation ensures a correct phase measurement with a quantum two-path interference. In contrast, we find that even in a situation where the anti-phase relation is less well-defined, the smooth phase shift in the AB oscillation can still occur but does not give the correct transmission phase due to contributions from multiple paths. This indicates that the phase relation of the two output currents in our interferometer gives a good criterion for the measurement of the true transmission phase, while the smooth phase shift in the AB oscillation itself does not.

Transmission phase in the Kondo regime revealed in a two-path interferometer.

We report on the direct observation of the transmission phase shift through a Kondo correlated quantum dot by employing a new type of two-path interferometer. We observed a clear π/2-phase shift, which persists up to the Kondo temperature TK. Above this temperature, the phase shifts by more than π/2 at each Coulomb peak, approaching the behavior observed for the standard Coulomb blockade regime. These observations are in remarkable agreement with two-level numerical renormalization group calculations. The unique combination of experimental and theoretical results presented here fully elucidates the phase evolution in the Kondo regime.

Direct Measurement of Vanadium Dioxide Dielectric Properties in W-band

In this paper we directly measure the refractive index and extinction coefficient of vanadium dioxide (VO2) in W-band (75-110 GHz) near the insulator-to-metal phase transition. A frequency-domain interferometry setup is used to obtain the transmission amplitude and phase shift of a transmitted wave though a 200 nm-thick VO2 film deposited on a silicon substrate. Using the transmission matrix technique, the measured data in the 58-100 °C temperature range are used to obtain the refractive index and extinction coefficient of VO2 as a function of temperature and frequency. The experimental results show a significant increase in the refractive index and extinction coefficient of VO2 beyond the transition temperature of ~68 °C.

Large Stroke Staggered Vertical Comb-Drive Actuator for the Application of a Millimeter-Wave Tunable Phase Shifter

This paper presents the design, fabrication, and characterization of a MEMS actuator with large static deflection as a waveguide-mounted variable millimeter-wave phase shifter. The actuator is composed of a pair of interdigitated microplates actuated by vertical comb-drives and suspended by SU-8 torsional springs. The SU-8 spring possesses a thin metallization top layer and a reverse-T-shaped cross-section enabling low torsional stiffness and high in-plane stability. A maximum mechanical deflection of 10.3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$^{\circ}$</tex></formula> is obtained under a dc actuation voltage of 35 V. The dynamic characterization of the device shows that the resonance frequency of the torsional mode is well separated from the other three bending modes, confirming the designed low torsional stiffness and high in-plane stability. The torsional viscoelastic creeping is measured as a function of time at different loads and shows a maximum of 0.5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$^{\circ}$</tex></formula> for an applied voltage of 27.5 V. A high operation cycle test is conducted and the metalized SU-8 spring withstands 800 million cycles without showing fatigue. RF measurements show that a variable mechanical deflection angle between 0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> and 8.2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> results in a variable transmission phase shift up to 58.0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> . The measured insertion loss is always below 5.1 dB at 98 GHz, corresponding to a figure of merit of 11.5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}/{\rm dB}$</tex> </formula> . [2012-0338]

Continuously variable W-band phase shifters based on MEMS-actuated conductive fingers

This paper presents four continuously variable W-band phase shifters in terms of design, fabrication, and radiofrequency (RF) characterization. They are based on low-loss ridge waveguide resonators tuned by electrostatically actuated highly conductive rigid fingers with measured variable deflection between 0.3° and 8.25° (at a control voltage of 0–27.5 V). A transmission-type phase shifter based on a tunable highly coupled resonator has been manufactured and measured. It shows a maximum figure of merit (FOM) of 19.5°/dB and a transmission phase variation of 70° at 98.4 GHz. The FOM and the transmission phase shift are increased to 55°/dB and 134°, respectively, by the effective coupling of two tunable resonances at the same device with a single tuning element. The FOM can be further improved for a tunable reflective-type phase shifter, consisting of a transmission-type phase shifter in series with a passive resonator and a waveguide short. Such a reflective-type phase shifter has been built and tested. It shows a maximum FOM of 101°/dB at 107.4 GHz. Here, the maximum phase shift varied between 0° and 377° for fingers deflections between 0.3° and 8.25°.