Pair Of Resonators Research Articles

Radial Migration of Gap-opening Planets in Protoplanetary Disks. II. The Case of a Planet Pair

Abstract When two planets are born in a protoplanetary disk, they may enter into mean-motion resonance as a consequence of convergent planetary migration. The formation of mean-motion resonances is important for understanding how planetary systems are shaped in disk environments. Motivated by recent progress in the comprehension of the migration of partial gap-opening planets, we have investigated the orbital evolution of planet pairs in a wide range of masses and disk properties with the aim to find out when resonance capture is likely to happen. Using the formula for the migration timescale of a gap-opening planet developed in our previous work, we have derived a simple criterion that allows us to predict when the migration will be convergent (divergent). Further, we have verified the criterion using two-dimensional hydrodynamic simulations. We have found that the resonant pair of planets formed at the early phase of evolution can depart from resonance at later times because the migration speed of the outer planet slows down due to gap formation. Moreover, adopting our formula for the migration timescale, we have also carried out three-body simulations, which confirm the results of hydrodynamic simulations. Finally, we have compared our predictions with observations, selecting a sample of known two-planet systems.

Quad-band linear terahertz frequency conversion in time-varying metasurfaces

In this Letter, a quad-band linear frequency conversion prototype is proposed and investigated in terahertz region based on a time-varying metasurface. The unit cell of the metasurface consists of four pairs of concentric split-ring resonators loaded with photoactive silicon. By changing the conductivity of photoactive silicon via optical pump, both static and time-varying metasurfaces are achieved and investigated. Numerical results show that the transmission spectrum of the static metasurface has four merged resonant frequencies at 0.49THz, 0.58THz, 0.71THz, 0.81THz respectively, and linear frequency conversion appears at these four frequencies under the modulation of time-varying metasurface. The conversion linearity is also verified by applying dual-band bandpass filters with different center frequency. The coefficients of determination are 0.98, 0.94, 0.87, 0.96 correspondingly. This prototype provides a new approach for realizing quad-band frequency conversion for ambient terahertz wave and has wide applications in terahertz imaging and communication systems.

Characterization of multilayer nano-absorbers

Full characterization of thin nano-carbon and nano-ferrite absorbers was performed in the frequency range 5-40 GHz by a combination of two microwave methods – a resonance one using a pair of cylindrical resonators with different excited modes, and a broadband one, where the samples cover a 50-ohm microstrip line. The results show a reliable extraction of the complex dielectric and magnetic parameters of 20-60-μm thick absorber layers by the resonance method considered (including the anisotropy of these parameters) and a successful verification of their values in the wide frequency range.

Resonant Excitation Analysis on Asymmetrical Lateral Leakage of Light in Finite Zero-Contrast Grating Mirror

Resonant excitation analysis on asymmetrical lateral leakage of light in the finite zero-contrast grating (ZCG) mirror is demonstrated, and the size effect of the excited source is investigated. The dispersion equation of slab waveguide for the TM mode is proposed to evaluate the resonant condition of the ZCG mirror, and it is shown that the mirror effect of the infinite ZCG is resulted from the overlapping of order-mode resonance pairs. However, two leaky channels are excited in spectra of the finite ZCG mirror for the normal-incident Gaussian source, where bound states in the continuums (BICs) turn into quasi-BICs as the angular component is nonzero. The leaky channels are confined in the grating layer and the sublayer, and they are all transferred from the symmetrical mode to the asymmetrical mode along the lateral direction from the center of the ZCG. The asymmetrical loss of the lateral leakage of light relative to incidence direction, in principle, can break reflection reciprocity of the symmetrical system of the finite ZCG mirror. By changing the excited source from the grating side to the sublayer side, the lateral leakage of light of the finite ZCG mirror can be efficiently reduced.

High energy acceptor states strongly enhance exciton transfer between metal organic phosphorescent dyes

Exciton management in organic light-emitting diodes (OLEDs) is vital for improving efficiency, reducing device aging, and creating new device architectures. In particular in white OLEDs, exothermic Förster-type exciton transfer, e.g. from blue to red emitters, plays a crucial role. It is known that a small exothermicity partially overcomes the spectral Stokes shift, enhancing the fraction of resonant donor-acceptor pair states and thus the Förster transfer rate. We demonstrate here a second enhancement mechanism, setting in when the exothermicity exceeds the Stokes shift: transfer to multiple higher-lying electronically excited states of the acceptor molecules. Using a recently developed computational method we evaluate the Förster transfer rate for 84 different donor–acceptor pairs of phosphorescent emitters. As a result of the enhancement the Förster radius tends to increase with increasing exothermicity, from around 1 nm to almost 4 nm. The enhancement becomes particularly strong when the excited states have a large spin-singlet character.

A simple and effective design method for multiband filtering power divider

This letter presents a simple and effective design method for multiband filtering power divider (FPD) in wireless communication systems. By elaborately coupling multiple pairs of stub-loaded resonators (SLRs) with input/output feedlines, a flexible topology for multiband FPD is built. Not only can each pair of the SLRs generate one passband, but also control the respective center frequency and bandwidth independently. Meanwhile, isolation resistors are arranged between each pair of the SLRs to independently adjust each band isolation, finally achieving nice isolation over a wide frequency band. To validate the design concept, a prototype triple-band FPD working at 1.30, 1.62, and 2.22 GHz is devised, simulated, and tested. Measurements have good agreement with simulations, indicating that the FPD has the advantages of its independently controllable frequency and bandwidth, high passband selectivity, and good isolation over a broadband frequency band.

Investigation of microstrip ultra-wideband bandpass filters

Ultra-wideband microwave filters with high frequency-selective properties have been developed by means of electrodynamic numerical analysis of 3D models. Microstrip structures, which are studied theoretically and experimentally, use one multimode resonator and a pair of single-mode resonators. There is fairly good agreement between the calculated data and the data taken on the experimental sample. The relative bandwidth of the manufactured microstrip filter is 60%.

Orthogonally dual‐polarised MIMO antenna array with pattern diversity for use in 5G smartphones

A new multiple-input/multiple-output (MIMO) antenna design is introduced for future smartphones. The proposed design contains four pairs of double-fed circular-ring resonators located at different edges of the smartphone printed circuit board (PCB) with an FR-4 substrate and a dimension of 75 × 150 mm2. The antenna elements are fed by 50-Ohm microstrip-lines and provide polarisation and radiation pattern diversity function due to the orthogonal placement of their feed lines. By inserting a rectangular slot under each microstrip feed-line, the mutual coupling characteristic of the antenna ports is reduced. A good frequency bandwidth (S11 ≤ − 10 dB) of 3.3–3.9 GHz has been obtained for the smartphone antenna array. Nevertheless, for S11 ≤ − 6 dB, this value is 3.1–4.3 GHz. More than 3 dB realised gain and 80% total efficiency are achieved for the single-element radiator. The design provides not only sufficient radiation coverage supporting different sides of the mainboard but also the polarisation diversity. In addition, sufficient properties are obtained in the vicinity of human-hand/human-head. The proposed MIMO antenna design is also capable to generate dual- or multi-band function. Moreover, a new and compact phased array millimeter-wave (mm-wave) antenna design with end-fire radiation beams is introduced which can be easily integrated into smartphones.

Analysis and design of compact four‐way single‐ and dual‐band filtering power dividers on a new adjustable multi‐mode topology

Four-way single-/dual-band operation integrated filtering power divider (FPD) with new design topology is presented in this study. For either single- or dual-passband response, it involves only one same-type pair of multi-mode resonators and three isolation resistors, comparing with other existing four-way FPDs. By adopting the even-/odd-mode analysis method to flexibly control the resonant modes of the designed resonator and select isolation resistances, both single- and dual-band four-way filtering power division responses are specified and derived with the same one configuration. The proposed four-way FPD designs stand out from the reported ones by both nice operation performance, flexible topology with reduced number of resonators, and no additional feeding network at input port. For demonstration, two prototypes for four-way single- and dual-band FPDs are implemented following the given design procedure, respectively. Both simulated and measured results are exhibited to verify the theoretical design concept.

Ultrafast polarization-dependent all-optical switching of germanium-based metaphotonic devices

Metamaterials play an important role in the modulation of amplitude and group delay in the terahertz (THz) regime on account of their optical properties, which are rare in natural materials. Here an ultrafast anisotropic switch of the plasmon-induced transparency (PIT) effect is experimentally and numerically demonstrated by metamaterial devices composed of two pairs of planar split-ring resonators and a pair of closed-ring resonators. By integration with a germanium (Ge) film, a recovery time of 3 ps and a decay constant of 785 fs are realized in the metadevice. Stimulated by the exterior optical pump, the PIT windows at different frequencies are switched off with an excellent property of slow light for vertical and horizontal THz polarizations, realizing an astonishing modulation depth as high as 99.06%. This work provides a new platform for ultrafast anisotropic metadevices tunable for amplitude and group delay.

Dual-Resonator MEMS Magnetometer Based on Self-Clocking Sigma-Delta Modulation

This paper presents the design and experimental evaluation of a micromachined Lorentz force magnetometer with a dual-resonator structure, interfaced with an electromechanical sigma-delta modulation (EM- $\Sigma \Delta {\text {M}}$ ) force rebalancing control loop. The magnetometer chip comprises a matched pair of resonators on the same silicon die. The closed-loop control circuit relies on a self-oscillating architecture; the frequency of which is determined by first resonator. It is used to generate a drive current injected to the second resonator, and also generates all internal circuit clocks based on a self-clocking scheme. System level simulation indicate a signal-to-noise ratio (SNR) larger than 100dB in a bandwidth of 64Hz with a 10mT, 32Hz magnetic field input ( ${B}$ ). The system was implemented in hardware based on a dual quantization technique, which has the advantage of reduced quantization error of multi-bit quantization in a single sigma-delta modulator. Experimental results demonstrate that proposed dual-resonator magnetometer achieved a 7-fold improvement in bias instability (increasing the averaging time to reach the bias instability from 1s to 8s) and the bandwidth (BW) is increased to ~80Hz, 16-fold higher compared to an open-loop magnetometer with a single resonator. With a 1mA bias current, the output noise is less than $1\mu \text{T}/\surd $ Hz for the z-axis magnetic field.

Compact Wide-Stopband Dual-Band Balanced Filter Using an Electromagnetically Coupled SIR Pair With Controllable Transmission Zeros and Bandwidths

This brief presents a dual-band balanced filter with wide stopband, controllable transmission zeros and bandwidths, and compact size based on a newly designed electromagnetically coupled stepped impedance resonator (SIR) pair. The proposed SIR contains three different impedance lines, which can lead to more degrees of design freedom for resonant frequency control. Two electrical length ratios of the SIR can be individually tuned to obtain two desired differential-mode (DM) resonant frequencies for dual-band design, while keeping the first spurious frequency far away for wide-stopband design. Moreover, an inherent common-mode (CM) suppression can also be obtained without adding extra structures due to the discriminating CM resonant frequencies. The mechanism of transmission zeros (TZs) generation is also investigated by means of phases and admittance analysis. It reveals that four TZs around the two operating bands can be flexibly controlled via adjusting the ratio of magnetic and electric coupling coefficients of the SIR pair as well as the coupling space of the feeding lines, which have greatly enhanced the passband selectivities and the band-to-band isolation. Subsequently, the graphs of coupling coefficients and external quality factors for the filter design are extracted, showing sufficient degrees of design freedom for bandwidth control. The proposed dual-band balanced filter is finally fabricated and measured at 1.75 GHz and 3.64 GHz, respectively. Measured results are in good agreement with the simulated ones. Compared with the state-of-the-art works, the proposed circuit performs a deeper and wider stopband of $4.5{f}_{1}^{d}$ with 40dB attenuation (where ${f}_{1}^{d}$ is the fundamental frequency), and more than 50-/45-dB in-band CM suppressions with compact size ( $0.14\lambda _{g} \times 0.27{\lambda }_{g}$ , where ${\lambda }_{g}$ is the guided wavelength of the fundamental frequency).

Dirac degeneracy and elastic topological valley modes induced by local resonant states

In elastic systems, the current technique to produce Dirac degeneracy is based on Bragg scattering eigenstates, which, however, suffers from operating only at relatively high frequency determined by lattice constant. Here, an elastic metamaterial plate that presents an analog to the quantum valley Hall effect (QVHE) is proposed to achieve Dirac degeneracy with local resonant states, enabling us to tune the operating frequency without altering the lattice. By introducing resonator pair into a hexagonal lattice, a local resonance states-induced Dirac cone is produced right below the local resonant band gap caused by the resonator pair. After gapping the Dirac cone with unequal masses of the resonator pair, a new local resonant band gap supporting topological edge modes immune to backscattering appears. This band gap is formed by mixing effective negative mass effect and Bragg scattering effect due to large virtual mass. These ideas are demonstrated by numerical simulation, as well as validated by the experiment on flexural wave in a textured plate. The proposed design provides a new degree of freedom to control elastic topological mode and paves the way to explore subwavelength elastic topological interface states.

Design of Filtering Crossover and Diplexer on SIW Quadruple-Mode Resonators in a Single Cavity

This paper at first presents the proposal and design of a filtering crossover and diplexer with two second-order filtering channels on substrate integrated waveguide (SIW) quadruple-mode resonators (QMRs) and in single cavities. The proposed method has an interesting application in the overall size miniaturization design. The proposed resonator is yielded with four perturbed modes (TE103, TE104, TE201 and TE202) featuring distinct electric field distributions by inserting metal via-holes in the center of a rectangular SIW cavity. Next, a pair of resonances is applied to form a second-order filter channel while TE201 and TE202 modes are implemented to realize the other, thereby integrating the whole circuit in a single cavity. Besides, the transmission responses between the channels are isolated only by the perturbed via-holes. Slots are introduced in the metal surface to further increase each channel design flexibility. In this way, controllable frequencies and compact size have been well achieved. Two examples including a crossover and diplexer with two second-order filter channels are designed, fabricated, and measured to verify. Good agreement between simulation and measurement can be observed.

Close-To-Touching Acoustic Subwavelength Resonators: Eigenfrequency Separation and Gradient Blow-Up

In this paper, we study the behaviour of the coupled subwavelength resonant modes when two high-contrast acoustic resonators are brought close together. We consider the case of spherical resonators and use bispherical coordinates to derive explicit representations for the capacitance coefficients which, we show, capture the system's resonant behaviour at leading order. We prove that the pair of resonators has two subwavelength resonant modes whose frequencies have different leading-order asymptotic behaviour. We, also, derive estimates for the rate at which the gradient of the scattered pressure wave blows up as the resonators are brought together.

Active Reconfigurable Ultra-Wideband Antenna With Complementary Frequency Notched and Narrowband Response

An active reconfigurable ultra-wideband antenna exhibiting complementary frequency notched and narrowband responses is proposed in this paper. The frequency responses are achieved on a CPW fed single element printed monopole antenna loaded with a pair of split ring resonators (SRR) and PIN Diodes. The SRRs and PIN Diodes embedded on the Coplanar Waveguide (CPW) feed works as an inline filter, when activated, exhibits frequency reconfigurability by transforming a frequency notched wideband antenna into a narrowband antenna. Different biasing conditions (reverse and forward) on the loaded PIN diodes toggle between frequency-notched and narrow band response of the antenna. Prototypes are fabricated and the measured impedance and radiation characteristics are presented. This concept offers multi-antenna functionality using a single radiator without any modification or addition to the radiator geometry.

Wideband Filtering Dumbbell-Shaped Slot Antenna With Improved Frequency Selectivity for Both Band-Edges

A novel wideband filtering dumbbell-shaped slot antenna with improved frequency selectivity for both band-edges is proposed in this paper. The filtering slot antenna is composed of a dumbbell-shaped slot, two parasitic patches, eight slot-stubs and a feeding line with a pair of step impedance resonator (SIR) stubs. An additional resonance is generated to increase the bandwidth and a gain null is produced at the upper band-edge to improve the frequency selectivity by loading parasitic patches in the dumbbell-shaped slot. Eight slot-stubs adjacent to the dumbbell-shaped slot are etched to enhance the impedance matching. In addition, the bandwidth is further broadened and two gain nulls are realized at both band-edges by adding a pair of SIR stubs. Moreover, the gain nulls can be adjusted individually by the length of parasitic patches or SIR stubs. As a result, the gain curve of the proposed filtering slot antenna has good flatness and the frequency selectivity for both band-edges is significantly improved. A prototype has been manufactured and measured to verify the validity of the design. The measured impedance bandwidth of |S 11 | <; -10 dB is 62.5% (2.2 GHz - 4.2 GHz). High suppression levels of 26 dB and 30 dB can be achieved in the lower and upper stopbands, respectively.

Влияние на энергию ковалентной связи изотопного состава формирующих ее ядер

In this paper, on the basis of the classical quantum-mechanical approach, an explanation is considered of the physical mechanism of isotope fractionation associated with the predominance of a certain number of neutrons among nucleons and explaining the nonequilibrium accumulation of certain forms of stable isotopes of biogenic elements in heterogeneous systems. The reasons for the detected neutron effect can be: the interaction of the magnetic moments of atomic nuclei and valence electrons, leading to a change in the distance between them, including the effect of the changed distance between atoms on the energy of the covalent bond between the resonant pairs of atoms.

Single-/Dual-Band Bandpass Filter-Integrated Single-Pole Double-Throw Switch Using Distributed Coupling Tri-Mode Resonators

This article presents a method to design a single-band (SB)/dual-band (DB) bandpass filter (BPF)-integrated single-pole double-throw (SPDT) switch by using one/two distributed coupling identical tri-mode resonator (TMR) pairs loaded with opposite polarity p-i-n diodes. Moreover, the proposed method is also directly suitable for designing the multiple-band (MB) BPF-integrated SPDT switch by simply increasing the used numbers of identical TMR pairs. As an example, a SB-BPF-integrated SPDT switch with the central frequency (CF) of 1 GHz and the ripple bandwidth (RBW) of 65 MHz is first designed by using one identical switchable TMR pair, so as to validate our design approach. Due to the inherent property of TMR and the introduced source–load coupling, high ON-state passband selectivity is achieved. Then, two switched 50- $\Omega $ matching circuits are connected to two noncommon feeding lines, and an SB-BPF-integrated SPDT switch with absorptive OFF-state property is also realized. Finally, a DB-BPF-integrated SPDT switch with CFs of 0.9 GHz/1.8 GHz and RBWs of 50 MHz/105 MHz is designed by simply employing two identical TMR pairs. When the operating states of two identical switchable TMR pairs are specifically chosen, the proposed DB-BPF-integrated SPDT switch exhibits multiple functions, i.e., the 900/1800 SB-BPF-integrated SPDT switches with absorptive OFF-state property, the 900/1800 DB-BPF-integrated SPDT switch with absorptive OFF-state property, and the 900/1800 diplexer-integrated SPDT switch. The measured results also show that these switches exhibit low ON-state passband losses, deep out-of-band rejections (OBRs) of ON-state passbands, high OFF-state suppressions (OSSs), high port-to-port isolations (PPIs), and compact circuit sizes.

Microwave Resonator for Eye Tracking

This article presents a novel microwave resonator for eye tracking. The system is implemented using coplanar waveguide technology and consists of two identical configurations with a pair of mirror-symmetrical open complementary split-ring resonators. These two sensors are combined with a wearable device placed on the eye and glass frame corners. The proposed evaluation uses two uncoupled and separate reflection magnitudes for differential cross modes. Each sensor has two resonance frequencies, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{L}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{H}$ </tex-math></inline-formula> , to detect horizontal and vertical eye sweeping, respectively. As the user’s focus sweeps left to right or up and down with the wearable device, the asymmetrical conditions of the eyelid and cornea enhance the variation in differential reflection magnitude. The paired sensors provide information for tracking eye action. By applying the resonator perturbation theory, the eyelid and eye cornea locations above the planar resonator location were analyzed using the equivalent permittivity and conductance loss relationship, respectively. The experimental results indicate that the resonator tracker can detect relative changes in eye gaze from 50° to 130° horizontally (average 8.81-dB variation) and from 40° to 140° vertically (average 9.43-dB variation). These eye sweeping directions, thus, connect at 90°. Initial calculations reveal that the optimal eye tracking function is achieved and that the tracking method is suitable for individual users.