Arrangement Of Resonators Research Articles

Miniaturized conductor‐backed CPW high‐pass filter for C‐band satellite applications

AbstractA miniaturized conductor‐backed coplanar waveguide high‐pass filter for C‐band satellite applications is presented in this article. It consists of high impedance line and hexagonal resonator with interdigital coupling implemented in coplanar by etching square ring metallic pattern at the ground plane of the substrate. The necessary transmission zero is obtained by the shunt connected square ring pattern. The hexagonal resonator arrangement is used to produce band pass characteristics and the back side strip introduces capacitance effect thereby improving the rejection level. Hence, the filter behaves as high‐pass filter. Design, simulation, and fabrication of Satellite C‐band high‐pass filter characteristics are investigated. The proposed filter yields excellent band width starts from 2 to 8 GHz at 10 dB. Hence, the proposed filter will be best suitable for Satellite C‐band applications. The overall size of filter is achieved to be 39 mm × 8 mm × 1.6 mm on accounting all the features. The fractional band width of the filter is calculated from bandwidth to center frequency ratio and it is found 120%. S‐parameter results of high‐pass filter are return loss (RL) S11 is about −30 dB and insertion loss (IL) S21 is −0.98 dB are obtained in simulation. Whereas in the measurement, the RL is nearly −25 dB and IL is −2 dB.

Spatially dispersive dichroism in bianisotropic metamirrors

Dichroism refers to the differential absorption of a material for different polarized waves and has important applications in polarimetry and optical wavefront manipulation. The coexistence of strong linear and circular dichroism at thin optical interfaces is usually challenging due to the weak chiral anisotropy in natural materials. Here, we investigate the spatially dispersive dichroism of bianisotropic metamirror, in which giant linear and circular dichroism can be achieved simultaneously. By covering the metallic mirror with an array of bianisotropic resonators, specific linearly and circularly polarized waves can be largely absorbed under normal and oblique incidences, respectively. This intriguing phenomenon is attributed to the anisotropic magneto-electric coupling, that is, the handedness and the strength of the equivalent transverse electric surface current are determined by the angle of incidence. Furthermore, dual-band and hybrid-chirality metamirrors for asymmetric spin reflection have been realized by adjusting the geometries and arrangement of the bianisotropic resonators. The overall thickness of the bianisotropic metamirror is only 1/50 of the wavelength and thus highly suitable for on-chip integration. Our findings may provide an alternative approach towards multifunctional optical mirrors, signal detectors, chiral imaging devices, and molecular analyzers.

Impact load wave transmission in elastic metamaterials

Structures that consist of resonating endo-structures within a load bearing exo-structure possess the ability to mitigate dynamic load within a fixed frequency range. Their dynamic behavior can be characterized by the enactment of negative effective mass density. This research work presents the design, fabrication and dynamic load characterization of a locally resonant elastic metamaterial. Mass–spring system with negative effective mass is experimentally investigated and numerically analyzed, with the aim to reveal stress wave transmission property in low-frequency range under impact loading. Local resonance frequencies of the basic unit cells are designed and generated using springs with different spring constants. Results evidently show that impact load mitigation occurs in the presence of internal resonators. Parametric studies reveal that wave attenuation performance is improved by using a variety of resonance frequencies in the local resonators design. In addition, alternating the arrangement of different local resonators have negligible influence on wave attenuation. A good agreement between numerical simulation and experimental testing is achieved. The significance of this work lies in the experimental and numerical evaluation of wave attenuation efficiency in elastic metamaterials, thus providing a strong foundation and design basis in the future potential of elastic metamaterials for impact protection applications.

Reconfigurable Split-Ring Resonators Using Pneumatic Levitation System

In this paper, a pneumatic levitation system is proposed to provide a contactless and metal free platform for dynamically altering the structural arrangement of split-ring resonators in an incident electromagnetic wave. One split ring is placed on a pneumatically levitated platform controlled by different levels of air pressure, and another identical but static split ring is placed underneath to form a broadside coupled arrangement. The proposed pneumatic levitation system has the capability to precisely control the relative orientation of the split ring to the desired rotational angle for on-demand reconfigurability without a sophisticated electrical or mechanical structure. In addition to the rotational angle, the separation between two SRRs can also be reliably controlled by adjusting the pneumatic pressure. The combination of both of these controls enables a large frequency configuration range for broadside coupled SRRs. The corresponding frequency tunability with a 35% bandwidth is validated by both simulations and measurements.

Polarization Selective Multiple Fano Resonances in Coupled T-Shaped Metasurface

The plasmonic responses of an array of coupled resonators are tailored to support multiple strong plasmonic Fano resonances at terahertz frequencies. The metasurface is formed by a periodic arrangement of T-shaped gold resonators. It is demonstrated that multiple Fano resonances can be achieved by breaking the symmetry of adjacent T-shaped resonators. Various configurations of the coupled T-shaped metasurface array are proposed, which support distinct multiple sharp Fano resonances with large modulation depths. Moreover, quality factors more than 130 are realized around Fano resonances, and an enhancement of the electric field exceeding 65 times around the hybridized modes is obtained. The highly dispersive polarization selective properties of the proposed coupled metasurface array are useful for various applications, including sensing, switching, and broadband slow-light devices.

Broadband transmission loss in the audible regime with a 3D sonic crystals by use of resonance overlap

The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in frequency by modifying the orientation of the square-rod scatterers with respect to the incident wave. In addition, the quarter wavelength resonators introduce resonant band gaps that can be tuned by coupling the neighbor resonators. Bragg and resonant band gaps can overlap allowing the wave propagation control inside the periodic resonant medium. In particular, we theoretically and experimentally show that this system can produce a broad frequency band gap exceeding two and a half octaves (from 590 Hz to 3220 Hz) with transmission lower than 3%. Finite element methods were used to calculate the dispersion relation of the locally resonant system. The visco-thermal losses were accounted for in the quarter wav...

Acoustic characteristics of damped metamaterial plate with parallel attached resonators

An acoustic metamaterial consisting of a homogeneous damped plate with parallel attached resonators is presented. Theoretical analysis shows that the metamaterial plate can generate multiple resonant-type band gaps and the lower-bound frequency of each band gap coincides with the resonance frequencies of the resonators. The parallel arrangement of resonators, compared with the metamaterial plate with resonators attached in series reported by Peng et al. (2015), results in a wider second band gap with a lower edge, while the first band gap is almost the same, creating therefore an easier combination of the multiple band gaps into a wider one. It is noted that damping has a significant influence on the band gaps and the effective mass density (especially for the damping of resonators). Specifically, it can be concluded that damping cannot be neglected in practical engineering applications, damping in the material of the host plate can smooth and lower the responses in the whole frequency range, especially in the higher frequency range, and a high level of damping of resonators deactivates the effect of band gaps. Such weak/damped resonators actualise the metamaterial damping poorly, and rather tend only to contribute to the overall damping such as the damping of the host plate.

Complex dispersion relation of surface acoustic waves at a lossy metasurface

The complex dispersion relation of surface acoustic waves (SAWs) at a lossy resonant metasurface is theoretically and experimentally reported. The metasurface consists of the periodic arrangement of borehole resonators in a rigid substrate. The theoretical model relies on a boundary layer approach that provides the effective metasurface admittance governing the complex dispersion relation in the presence of viscous and thermal losses. The model is experimentally validated by measurements in the semi-anechoic chamber. The complex SAW dispersion relation is experimentally retrieved from the analysis of the spatial Laplace transform of the pressure scanned along a line at the metasurface. The geometrical spreading of the energy from the speaker is accounted for, and both the real and imaginary parts of the SAW wavenumber are obtained. The results show that the strong reduction of the SAW group velocity occurs jointly with a drastic attenuation of the wave, leading to the confinement of the field close to the source and preventing the efficient propagation of such slow-sound surface modes. The method opens perspectives to theoretically predict and experimentally characterize both the dispersion and the attenuation of surface waves at structured surfaces.

A simple topology metamaterial blackbody for visible light

Because they can absorb nearly all of the light incident upon them, metamaterial-based blackbodies have many potential applications and have been studied widely. However, the topological structure of most designed metamaterial blackbodies so far is too complicated, at least involving a three-layer structure, to be fabricated and used, especially in the optical band. Here, we designed a simple topology metamaterial blackbody that contains only two layers. The top layer is a periodic arrangement of subwavelength silicon resonators, and the bottom one is a continuous Au film. The simulated results showed that the proposed structure produced a perfect absorption peak in the spectrum because of the Mie resonance of the silicon resonator, the localized surface plasmon resonance of the Au film, and the appropriate losses of the dielectric and metal materials. Furthermore, the impact of the geometrical and material parameters and the incident and polarization angles on the absorption spectrum were studied in depth. Finally, the physical mechanism underlying the blackbody was also studied. All of the results indicate that the designed metamaterial blackbody has many salient features and can be used in devices such as solar cells and bolometers.

Broadband Transmission Loss Using the Overlap of Resonances in 3D Sonic Crystals

The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in frequency by modifying the orientation of the square-rod scatterers with respect to the incident wave. In addition, the quarter wavelength resonators introduce resonant band gaps that can be tuned by coupling the neighbor resonators. Bragg and resonant band gaps can overlap allowing the wave propagation control inside the periodic resonant medium. In particular, we show theoretically and experimentally that this system can produce a broad frequency band gap exceeding two and a half octaves (from 590 Hz to 3220 Hz) with transmission lower than 3%. Finite element methods were used to calculate the dispersion relation of the locally resonant system. The visco-thermal losses were accounted for in the quarter wavelength resonators to simulate the wave propagation in the semi-infinite structures and to compare the numerical results with the experiments performed in an echo-free chamber. The simulations and the experimental results are in good agreement. This work motivates interesting applications of this system as acoustic audible filters.

Design of Compact Microstrip Sept-Band Bandpass Filter With Flexible Passband Allocation

A compact sept-band bandpass filter (BPF) with flexible passband allocation has been presented. By introducing the multiple coupling paths, all passbands can be fully controlled and designed independently. The first and last resonators are used to not only create one of the passbands but also serve as the input and output coupling structure for the other passbands. Thus, more operating bands can be obtained without increasing extra circuit area. The special arrangement of resonators could help to reduce the filter size and create more operating bands. For demonstration, a two-pole sept-band BPF centering at 1.05, 1.3, 1.5, 1.8, 2.05, 2.35, and 2.85 GHz has been designed and fabricated with microstrip technology. The sept-band BPF has an extremely small size of 0.14 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> by 0.19 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> . Moreover, good agreement is achieved between simulation and measurement.

The role of electromagnetic interactions in second harmonic generation from plasmonic metamaterials

We report on second harmonic generation spectroscopy on a series of rectangular arrays of split-ring resonators. Within the sample series, the lattice constants are varied, but the area of the unit cell is kept fixed. The SHG signal intensity of the different arrays upon resonant excitation of the fundamental plasmonic mode strongly depends on the respective arrangement of the split-ring resonators. This finding can be explained by variations of the electromagnetic interactions between the split-ring resonators in the different arrays. The experimental results are in agreement with numerical calculations based on the discontinuous Galerkin time-domain method.

A Fully Canonical Bandpass Filter Design Using Microstrip Transversal Resonator Array Configuration

This paper proposes a new and simple microstrip bandpass filter structure for the design of a fully canonical transversal array filter. The filter is constructed by the parallel arrangement of microstrip even-and odd-mode half-wavelength resonators. In this filter, transmission zeros (TZs) are not produced by cross couplings used in conventional filter designs, but by an intrinsic negative coupling of the odd-mode resonators having open ends with respect to the even-mode resonators with shorted ends. Thus, the control of the resonant frequency and the external Q factor of each resonator makes it possible to form both a specified passband and TZs. As an example, a fully canonical bandpass filter with 2-GHz center frequency, 6% bandwidth, and four TZs is synthesized with a coupling-matrix optimization, and its structural parameters are designed. The designed filter achieves a rapid roll-off and low-loss passband response, which can be confirmed numerically and experimentally.

Microfluidically Reconfigurable Metallized Plate Loaded Frequency-Agile RF Bandpass Filters

Microfluidically repositionable metallized plates have been recently introduced as a technique to realize frequency-agile bandpass filters with low insertion loss (IL) and wideband continuous frequency tunability. This paper utilizes a hybrid (circuit and electromagnetic simulation) model for time efficient simulations and introduces fourth-order bandpass filter designs for the first time to extend the applicability of the technique to higher order frequency-agile RF filter design. The paper introduces novel microfluidic channel and resonator configurations to demonstrate that the proposed filters can serve application specific footprint needs. By resorting to a selectively metallized plate approach, the reliability issue associated with synchronized movement of multiple metallized plates has been resolved. The filters are incorporated with micropumps to enable their automated control. Specifically, the concepts are demonstrated through design, fabrication, and testing of two fourth-order bandpass filters exhibiting different resonator arrangement layouts. The filters were measured to operate over $\sim $ 2:1 (60%) frequency tuning range (0.8 GHz –1.5 GHz) with better than 4.5 dB IL, $\sim $ 5% constant fractional bandwidth (FBW), and $>$ 40 dB out of band rejection implying a good agreement with the simulation based performance predictions. For the selected micropumps and investigated microfluidic channel layouts, the best tuning speed was measured to be 2.12 MHz per millisecond.

Optimization of a horizontal slot waveguide biosensor to detect DNA hybridization.

A full-vectorial H-field formulation-based finite element approach is used to optimize a biosensor structure incorporating a horizontal slot waveguide. It is designed to detect DNA hybridization through the change of the effective index of the waveguide structure. The key parameters, such as normalized power confinement, power density, change in effective index, and sensitivity are presented by optimizing the device parameters of the slot waveguide. It is shown here that a 90.0μm long compact Mach-Zehnder section can be designed with horizontal slot waveguide to detect DNA hybridization and for a ring resonator arrangement a sensitivity of 893.5nm/RIU is obtained.

Effective medium theory for elastic metamaterials in thin elastic plates

An effective medium theory for resonant and non-resonant metamaterials for flexural waves in thin plates is presented. The theory provides closed-form expressions for the effective parameters of arrangement of inclusions or resonators in thin plates as a function of the filling fraction of the inclusions, their physical properties and the frequency. It is shown that positive or negative effective elastic parameters are possible depending on the symmetry of the resonance but, unlike it happens for bulk elastic waves, the responsible for the negative mass density behaviour is the monopolar term, while the negative Young's modulus and Poisson's ratio is due to the combination of monopolar and quadrupolar resonances, showing also that, at least for the first order in the scattering coefficients, the dipolar resonance plays no role in the description of the effective medium. Several examples are given for both non-resonant and resonant effective parameters and the results are verified by multiple scattering theory.

Experimental Analysis of Wireless Power Transmission with Spiral Resonators

In this paper, a theoretical and experimental analysis of wireless power transfer through a coplanar resonator array is presented. In particular, six identical spiral resonators are used to form an array and transfer power between an emitter and a receiver. All the spiral resonators resonate at about 20 MHz and the emitter and receiver coils are designed with formulas taken from literature. The resonator system is modeled using mutual inductances, being retardation not significant. The transmission coefficient is measured for four different arrangements of the six resonators and the experimental measurements are compared with the theoretical predictions, showing similar trends. The paper shows that the peaks of the transmission coefficient vary slightly for the resonator arrangements considered.

Continuous-wave violet generation at 373.5 nm by frequency-doubled power-scaled near-infrared emitting Pr:YAlO3 laser

We report on a continuous-wave Pr:YAlO3 laser operating at a wavelength of 373.5 nm in a power-scaled resonator arrangement. Violet light generation has been achieved by intracavity frequency doubling of the near-infrared emitting Pr:YAP laser at a fundamental wavelength of 747 nm. For active medium pumping, two GaN laser diodes providing up to 1 W of output power each at 448 nm were used. By employing BBO crystal as a nonlinear medium, more than 46 mW of violet radiation has been obtained.

Realization of High-Q Fano Resonances in Ceramic Dielectric Metamaterials for Sensing Applications

Ceramic all-dielectric metamaterials are found to support very high Q resonances of the Fano-type, which until recently were largely attributed to the atomic physics phenomena. It is shown that proper arrangement of ceramic resonators in the metamaterial array allowsd for obtaining Q factors up to 15000. Thus high Q factors could be employed for new applications, in particular, for advanced sensing. An opportunity to design compact arrays that could be incorporated in a microwave sensor fed by a microstrip line is demonstrated. Numerical experiments have confirmed that Fano resonances in such arrays conserve high sensitivity to the dielectric permittivity of the controlled media.

The sounds of nanoscience: acoustic STM analogues

A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build an acoustic analogue of a quantum corral. The acoustic models foster reflections about the nature of STM images and elucidate the productive tension of imaging and imagining matter at the nanoscale.