Parallel Metal Plates Research Articles

Visualization of the Charging of Water Droplets Sprayed into Air.

Water droplets are spraying into air using air as a nebulizing gas, and the droplets pass between two parallel metal plates with opposite charges. A high-speed camera records droplet trajectories in the uniform electric field, providing visual evidence for the Lenard effect, that is, smaller droplets are negatively charged whereas larger droplets are positively charged. By analyzing the velocities of the droplets between the metal plates, the charges on the droplets can be estimated. Some key observations include: (1) localized electric fields with intensities on the order of 109 V/m are generated, and charges are expected to jump (micro-lightening) between a positively charged larger droplet and the negatively charged smaller droplet as they separate; (2) the strength of the electric field is sufficiently powerful to ionize gases surrounding the droplets; and (3) observations in an open-air mass spectrometer reveal the presence of ions such as N2+, O2+, NO+, and NO2+. These findings provide new insight into the origins of some atmospheric ions and have implications for understanding ionization processes in the atmosphere and chemical transformations in water droplets, advancing knowledge in the field of aerosol science and water microdroplet chemistry.

Heat transfer characteristics of solid-liquid interface on nanostructure surface under external electric field

With the size of high-performance electronic device decreasing (down to nanoscale), and the accompanying heat dissipation becomes a big problem due to its extremely high heat generation density. To tackle the ever-demanding heat dissipation requirement, intensive work has been done to develop techniques for chip-level cooling. Among the techniques reported in the literature, liquid cooling appears to be a good candidate for cooling high-performance electronic devices. However, when the device size is reduced to the sub-micro or nanometer level, the thermal resistance on the solid-liquid interface cannot be ignored in the heat transfer process. Usually, the interfacial thermal transport can be enhanced by using nanostructures on the solid surface because of the confinement effect of the fluid molecules filling up the nano-grooves and the increase of the solid-liquid interfacial contact area. However, in the case of weak interfacial couplings, the fluid molecules cannot enter into the nano-grooves and the interfacial thermal transport is suppressed. In the present work, the heat transfer system between two parallel metal plates filled with deionized water is investigated by molecular dynamics simulation. Electronic charges are applied to the upper plate and lower plate to create a uniform electric field that is perpendicular to the surface, and three types of nanostructures with varying size are arranged on the lower plate. It is found that the wetting state at the solid-liquid interface can change from Cassie state into Wenzel state with strength of the electric field increasing. Owing to the transition from the dewetting state to wetting state (from Wenzel to Cassie wetting state), the Kapitza length can be degraded and the solid-liquid interfacial heat transfer can be enhanced. The mechanism of the enhancing hart transfer is discussed based on the calculation of the number density distribution of the water molecules between the two plates. When the charge is further increased, electrofreezing appears, and a solid hydrogen bonding network is formed in the system, resulting in the thermal conductivity increasing to 1.2 W/(m·K) while the thermal conductivity remains almost constant when the electric charge continues to increase.

Casimir–Lifshitz Frictional Heating in a System of Parallel Metallic Plates

The Casimir–Lifshitz force of friction between neutral bodies in relative motion, along with the drag effect, causes their heating. This paper considers this frictional heating in a system of two metal plates within the framework of fluctuation electromagnetic theory. Analytical expressions for the friction force in the limiting cases of low (zero) temperature and low and high speeds, as well as general expressions describing the kinetics of heating, have been obtained. It is shown that the combination of low temperatures (T < 10 K) and velocities of 10–103 m/s provides the most favorable conditions when measuring the Casimir–Lifshitz friction force from heat measurements. In particular, the friction force of two coaxial disks of gold 10 cm in diameter and 500 nm in thickness, one of which rotates at a frequency of 10–103 rps (revolutions per second), can be measured using the heating effect of 1–2 K in less than 1 min. A possible experimental layout is discussed.

Excitation of THz plasmonic eignmode of parallel plain waveguide by using GaAs material

A Terahertz wave incident on waveguide made up of two parallel thin metal plates sandwiching a thin region of GaAs semiconductor, excites a surface plasma wave (SPW), at the metal–semiconductor interface. As the frequency of SPW increases the real part of the propagation vector increases linearly where the imaginary part of the propagation vector decay parabolically. It is also observed that the distortion of the pulse due to the Terahertz wave (THz) has different component of different phase velocity. The proposed methodology entails the generation of terahertz plasmonic eigenmodes within a parallel planar waveguide composed of GaAs material. The areas of focus in this field include THz Waveguiding and Routing, THz Modulators and Switches, THz Sensing and Imaging and THz Integrated Photonics.

Theory of dielectric photonic crystals sandwiched between parallel metal plates

Photonic crystals based on silicon-air-geometries sandwiched between parallel metal plates are studied theoretically. Compared with in-plane propagation in corresponding infinite-height photonic crystals, modes with one of the two possible polarizations are eliminated for small plate separations. Consequently, 2D photonic crystals that usually do not have a band gap for both polarizations possess a complete band gap in the sandwich geometry. A procedure for obtaining the maximum allowed photonic-crystal height between plates that preserves the in-plane band gap is described. The effect on the band gap of adding an air-gap or a silicon substrate to the photonic crystal structure between plates is also studied. Finally, it is shown that, for terahertz frequencies, a useful distance between metal plates is comparable to the thickness of thin silicon wafers, and that propagation losses are sufficiently small that the structures are of practical interest. We briefly discuss the numerical method that was used for calculating band diagrams and band gaps, which is based on a modification to the plane-wave-expansion method [R. D. Meade et. al., Phys. Rev. B 48, 8434 (1993)10.1103/PhysRevB.48.8434] based on an iterative search algorithm exploiting Fast Fourier Transforms for fast calculations.

Increased fatigue resistance in transparent lead zirconate titanate thin films with interdigitated electrodes

This work compares the fatigue behavior of fully transparent lead zirconate titanate films with a composition at the morphotropic phase boundary on fused silica glass or sapphire, respectively, fitted with coplanar interdigitated top electrodes and no bottom electrodes to that of the same systems in a traditional metal–insulator–metal parallel plate capacitor geometry. While the polarization hysteresis in the latter geometry decreases rapidly during bipolar electrical cycling, systems with coplanar electrodes show no notable fatigue up to 107 cycles. The difference is explained based on the columnar microstructure of the films: for coplanar electrode geometries, the grain boundaries of the columnar structure act as trapping sites for oxygen vacancies, preventing the build-up of agglomerates that cause fatigue by domain wall pinning.

A bi-dimensional compressed Luneburg lens antenna for miniaturization based on transformation optics

Transformed Luneburg lens has been widely employed to provide aberration-free imaging and high-gain antenna system, but whose focal plane and beam scanning range decrease correspondingly. In this paper, a two-dimensional compressed elliptical cylindrical Luneburg lens is presented based on transformation optics (TO) to achieve miniaturization and wide-angle beam steering. The Jacobian matrix and the permittivity tensor are calculated after supposing formulas to compress the focal plane, while maintaining the lens’ inherent performance. The gradient permittivity is achieved by two ring-type periodic unit cells on the basis of the Equivalent Medium Theory. The lens is then attached between a pair of parallel metal plates to further improve its gain and lower the side lobe level (SLL). To demonstrate this assumption, a prototype of this Luneburg lens is manufactured by isotropic material and 3D printing technique. The antenna operates at 3.3–5 GHz with a peak gain of 16.1/15.9 dBi. A 2D beam scanning range of ±50° and ± 20° can be implemented by merely five feeds, the side lobe level keeping less than -16.3/-16 dB. Measured results coincide well with theoretical predictions, offering a beneficial transformation mapping to both microwaves and optics.

Steering of Beam Using Cylindrical Arrangements in a Metallic Parallel Plates Structure Operating over Ku-Band

A novel flat beam steering prototype based on the specific arrangement of a cylindrical unit cell is designed, manufactured and tested. The wideband and broad scanning capability is demonstrated at the Ku-band. We have considered two configurations, first with circular rings (CR) of the defined permittivity values for respective radial distance from the center of the aperture, second with cylindrical rods that shall be placed on a respective CR, which mimics the defined permittivity. The structure is generated from Vero CMYK full color wax, which utilizes the Multijet 3D printing method. The proposed prototype is designed in the operating frequency of 12 GHz (λ = 25 mm) and separation distance between the two parallel plates are maintained at 12.5 mm (0.5λ) for the TE10 mode of operation. The diameter of the two parallel plates and the proposed structure is of 100 mm (4λ) where the radius of cylinders varies from 0.5 to 3.5 mm and corresponding relative permittivity varies from 0.6687 to 2.4395. The overall height of the structure is 12.5 mm and is placed between two parallel plates. The minimum separation distance is maintained between the proposed structure and the feed WR-75 waveguide. Irises effect is performed to obtain impedance matching in the operating frequency bands. Beam steering of the radiated waves is observed for relative rotation angles of 0∘, 30∘, 45∘, 75∘ and 90∘ of the WR-75 waveguide along the edge of parallel plates. The overall proposed system weighs 179 g, which signifies the light weight characteristics. Moreover, the proposed structure shows low return loss over 10 GHz to 15 GHz operating frequency band.

A Near-Field Motion Detection Technique Based on a Resonant Magnetic Probe

This letter proposes a near-field motion detection technique based on a resonant magnetic-field probe. The resonant magnetic-field probe consists of a parallel metal plate and a quarter-wave impedance transformer to make the input impedance 50 &#x03A9;. The 5.8-GHz radio frequency (RF) front-end is designed, which consists of a hybrid coupler and the proposed resonant magnetic-field probe that can be regarded as a full duplex antenna. Then, a 5.8-GHz continuous-wave Doppler radar transceiver is designed and integrated with the RF front-end to build the near-field radar system. The equivalent circuit of the RF front-end while detecting the targets in near-field is analyzed, in which the probe loop and the matching circuitry are modeled as a parallel <i>RLC</i> circuit and the coupler and transmission lines are equivalent to a lossy transmission line and an attenuator. The experimental results demonstrate that the proposed system can detect submillimeter displacement motions in the near-field.

Plasmon-induced transparency in a reconfigurable composite valley photonic crystal.

We propose a new kind of reconfigurable topological valley photonic crystal (TVPC), and a novel topological waveguide can be formed by constructing a domain wall between two TVPCs with opposite valley-Chern indices. The topological waveguide mode in the composite TVPC has large group refractive index. A topologically protected coupled waveguide cavity system is then designed by introducing a hexagonal ring cavity at the center of the straight domain wall of a combined TVPC, in which a narrow plasmon induced transparency window rises at 3.8848 GHz with a Q-factor of 1387 and a maximum group refractive index as high as 186. We propose a notch filter with a resonant frequency of 3.8852 GHz and a very high Q-factor of 10224. By changing the refractive index of liquid crystals via an external voltage applied between two parallel metal plates, the filter can be switched between band-pass and band-stop based on the reconfigurable topological interface state.

Topological One-Way Edge States in an Air-Hole Honeycomb Gyromagnetic Photonic Crystal

Topological one-way edge states have attracted increasing attention because of their intriguing fundamental physics and potential applications, particularly in the realm of photonics. In this paper, we present a theoretical and numerical demonstration of topological one-way edge states in an air-hole honeycomb gyromagnetic photonic crystal biased by an external magnetic field. Localized horizontally to the edge and confined in vertical direction by two parallel metallic plates, these unique states possess robust one-way propagation characteristics. They are strongly robust against various types of defects, imperfections and sharp corners on the path, and even can unidirectionally transport along the irregular edges of arbitrary geometries. We further utilize the one-way property of edge states to overcome entirely the issue of back-reflections and show the design of topological leaky wave antennas. Our results open a new door towards the observation of nontrivial edge states in air-hole topological photonic crystal systems, and offer useful prototype of robust topological photonic devices, such as geometry-independent topological energy flux loops and topological leaky wave antennas.

Electrostatic-Elastic MEMS with Fringing Field: A Problem of Global Existence

In this paper, we prove the existence and uniqueness of solutions for a nonlocal, fourth-order integro-differential equation that models electrostatic MEMS with parallel metallic plates by exploiting a well-known implicit function theorem on the topological space framework. As the diameter of the domain is fairly small (similar to the length of the device wafer, which is comparable to the distance between the plates), the fringing field phenomenon can arise. Therefore, based on the Pelesko–Driscoll theory, a term for the fringing field has been considered. The nonlocal model obtained admits solutions, making these devices attractive for industrial applications whose intended uses require reduced external voltages.

Quantum dissipation and friction attributed to plasmons

In this paper, we computed quantum friction of two parallel metal plates separated by a small distance moving with constant relative velocity [Formula: see text]. The plasmons as the internal degrees of freedom living on the two plates are coupled to a vacuum field in the gap between the two plates. We got the in–out quantum action which contained all the dynamical information of the system. Furthermore, we associated the imaginary part of the in–out quantum action with dissipation and frictional force. For the case of dispersionless plasmons, the imaginary part of the in–out quantum action is strongly suppressed as [Formula: see text]. The frictional force exhibits the same feature as [Formula: see text]. The difference is that the frictional force increases as [Formula: see text] and decreases as [Formula: see text]. For the case of dispersive plasmons, there is a threshold for the imaginary part of the in–out quantum action and the frictional force, that is, there is no dissipation when the relative velocity [Formula: see text] is not big enough. We gave a classical argument of the existence of the threshold, and this argument matched the mathematical results.

Broadband Metamaterial-Based Dual-Polarized Patch Antenna With High Isolation and Low Cross Polarization

A broadband metamaterial-based dual-polarized (DP) patch antenna fed by a cross aperture coupling through striplines is investigated. A metamaterial-based radiating patch with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\,\,\times4$ </tex-math></inline-formula> cells is designed to achieve broadband radiation by generating two resonant modes with the help of a cross aperture antenna. The cross aperture antenna fed by two orthogonal feed networks is arranged right underneath the patch to obtain DP operation. Both the feed networks based on striplines are sandwiched by a pair of parallel metallic plates to reduce cross-polarization. Vias are used to enhance the isolation by suppressing the coupling among cross apertures and stripline-based feed networks caused by parallel-plate mode. Moreover, the working mechanism of coupling reduction is analyzed by characteristic mode analysis (CMA) and electric field analysis. A prototype of the antenna has been fabricated. The measured results indicate that the DP patch antenna exhibits impedance bandwidths (voltage standing wave ratio (VSWR) ≤2) of 46.9% for Port V and 45.8% for Port H. The cross-polarization levels above the ground plane are less than −28 dB, and the isolation better than 40 dB within the impedance bandwidth.

Casimir effect for magnetic media: Spatially nonlocal response to the off-shell quantum fluctuations

We extend the Lifshitz theory of the Casimir force to the case of two parallel magnetic metal plates possessing a spatially nonlocal dielectric response. By solving Maxwell equations in the configuration of an electromagnetic wave incident on the boundary plane of a magnetic metal semispace, the exact surface impedances are expressed in terms of its magnetic permeability and longitudinal and transverse dielectric functions. This allows application of the Lifshitz theory with reflection coefficients written via the surface impedances for calculation of the Casimir pressure between magnetic metal (Ni) plates whose dielectric responses are described by the alternative nonlocal response functions introduced for the case of nonmagnetic media. It is shown that at separations from 100 to 800~nm the Casimir pressures computed using the alternative nonlocal and local plasma response functions differ by less than 1\%. At separations of a few micrometers, the predictions of these two approaches differ between themselves and between that one obtained using the Drude function by several tens of percent. We also compute the gradient of the Casimir force between Ni-coated surfaces of a sphere and a plate using the alternative nonlocal response functions and find a very good agreement with the measurement data. Implications of the obtained results determined by the off-shell quantum fluctuations to a resolution of long-standing problems in the Casimir physics are discussed.

Radiation Pattern Reconfigurable Antenna for IoT Devices

Based on the characteristic mode theory, a versatile radiation pattern reconfigurable antenna is proposed. The analysis starts from two parallel metallic plates with the same and different dimensions. By means of two PIN diodes, the size of one of the parallel metallic plates can be modified and consequently the behavior of the radiation pattern can be switched between bidirectional and unidirectional radiation patterns. Moreover, a SPDT switch is used to adjust the frequency and match the input impedance. The reconfigurable antenna prototype has been assembled and tested, and a good agreement between simulated and measured results is obtained at 2.5 GHz band which fits the IoT applications.

Monitoring Kekenyalan Tahu Kedelai dengan Sensor Kapasitif Menggunakan Mikrokontroller Berbasis Android

Tofu has the best quality vegetable protein because it has the most complete amino acid composition and is believed to have high digestibility (85% -98%). According to SNI 01-3142-1998 and SII No. 0270-1990 testing criteria for soy tofu based on smell, taste, color, appearance, or texture. Tofu soybeans are prone to physical or texture damage due to factors such as inappropriate pH levels and insufficient storage which results in damaged tofu. Therefore in this study, it is proposed to determine the elasticity of soy tofu with the parameters tested are the pH level in the manufacture of soy tofu, the storage temperature, and the capacitance value to see how thick the tofu is with a capacitive sensor using the capacitor principle. Where the parallel plate capacitor is a capacitor consisting of two parallel metal plates. The test results of all sensors are sent to the database and will be displayed on the page on the Android application which will provide real-time sensor output information to the user. Based on the results of testing on this system using a pH sensor, the pH value is around 3-4 which indicates that the pH level used is very good for use in tofu processing, at pH 4.56 with storage at 29 ° C the highest elastic capacitance value is 3.58. In testing data delivery, the throughput value is 4336,217 b / s and the smallest delay value is 0.017ms because the smaller the delay value, the better the quality of data transmission because there will be no delay in sending data.

Casimir entropy and nonlocal response functions to the off-shell quantum fluctuations

The nonlocal response functions to quantum fluctuations are used to find asymptotic expressions for the Casimir free energy and entropy at an arbitrarily low temperature in the configuration of two parallel metallic plates. It is shown that by introducing an alternative nonlocal response to the off-the-mass-shell fluctuations the Lifshitz theory is brought into agreement with the requirements of thermodynamics. According to our results, the Casimir entropy calculated using the nonlocal response functions, which take into account dissipation of conduction electrons, remains positive and monotonously goes to zero with vanishing temperature, i.e., satisfies the Nernst heat theorem. This is true for both plates with perfect crystal lattices and for lattices with defects of structure. The obtained results are discussed in the context of the Casimir puzzle.

Analysis of two‐dimensional multipactor model for ferrite circulator junction

Based on the Vaughan model, a simplified two-dimensional multipactor model of the circulator junction is established in this paper. It consists of two parallel metal plates and a dielectric plate that is vertical to the metal plate. A radio frequency electric field is applied between the two metal plates, and an electrostatic field exists on the dielectric surface. The trajectory of the electron can be obtained by solving the dynamic equation satisfied by the electron. And the influence of different electrostatic fields applied to the dielectric on the trajectory of electrons is analyzed. It is found that with the increase of the electrostatic field, the electrons quickly approach the dielectric plate, and finally move near the dielectric plate. Also, the total number of secondary electrons is decreasing accordingly. So, the multipactor discharge tends to go out. This conclusion can provide an idea for the suppression of the multipactor. Namely, applying a suitable electrostatic field on the dielectric surface can suppress multipactor involved in circulator junction.

3-D Printed Cylindrical Luneburg Lens for Dual Polarization

In this letter, a 2-D Luneburg lens sandwiched by two parallel metallic plates is proposed. To support both the vertical and the horizontal polarizations, parallel plate waveguide (PPW) theory is applied to analyze the proposed lens. The results shown that the height of the lens and the consistence of the gains for each polarization has a tradeoff relation. The optimized height of the lens is approximate one operating wavelength. To verify our idea, a cylindrical Luneburg lens is fabricated using 3-D printing technique with a radius of 4.65 λ 0. Using effective medium theory, the relative permittivity in each region of the lens can be obtained by adjusting the air-to-space ratio of the meta-atoms in that region. A dual-polarized patch antenna working around 15 GHz is used to feed the lens. The measured results agree well with the simulated ones, which prove that the gains of the two polarizations can be designed as equality by setting a suitable height of the lens. The measured gain is 15.1 dBi for vertical polarization and 14.7 dBi for horizontal polarization at 15 GHz. The lens-antenna system launches beams which points at −60°, −20°, 20°, 60° in the measurement for verification. The proposed Luneburg lens is suitable for base station which has the requirement of dual-polarized multibeam antennas.