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Tuning the center frequencies and bandwidth of dual passbands using circular arc perturbation slot in compact substrate integrated waveguide (SIW) filter is presented here. A miniaturized SIW cavity is extracted from circular SIW cavity and perturbation slot is loaded to disturb the excited modes. After rightly placing the slot, the arc angle is adjusted to change the surface current path of the excited modes and control the frequency of resonance and passband bandwidth. 1st passband center frequency (CF) can be tuned within a range of 1.23 GHz while 2nd passband remains almost unchanged when the slot is placed 12 mm away from cavity center. If the slot is placed 8 mm away from the cavity center, 1 GHz shift in CF and 1.2 GHz change in 3dB BW of 2nd passband is attained keeping 1st passband undisturbed. Minimum insertion losses of passbands during the process of tuning are maintained within 1.2dB.

It is a key problem to locate a buried target in UXO detection. The inversion algorithm based on the principle of least squares requires a large number of forward calculations to estimate the position of a target. The method of auxiliary sources (MAS) which can directly locate a UXO-like target is presented here without forward calculation. With a brief description of single dipole model for a UXO-like target, the basis of target location with magnetic field and scalar magnetic potential is deduced theoretically. Auxiliary sources made of elementary magnetic dipoles on a plane are applied to estimate the equivalent scalar magnetic potential from the measured magnetic field. Firstly, the moment of elementary magnetic dipoles is estimated by matching the measured magnetic field with the auxiliary sources modeled field. Then, the equivalent scalar magnetic potential is calculated with these elementary magnetic dipoles without a priori knowledge of the target’s location. Finally, the position is calculated directly with the measured magnetic field and the equivalent scalar magnetic potential. The responses of four UXOs excited by a z-component square transmitting coil are recorded by a 9×9 3-component receiving coil array. With the auxiliary sources on a plane under the measurement grid, the equivalent scalar magnetic potential is calculated precisely. Experimental results show that the measured magnetic field matches well with the auxiliary sources modeled field, and the estimated positions of all targets are highly consistent with the measured ones. The horizontal error is within 2 cm, and the depth error is within 6 cm.

This work presents the characterization of the electrical permittivity of typic quartzipsamment soil, found in the Restinga de Cabedelo National Forest (Cabedelo FLONA). For measurement, a rectangular resonant cavity was constructed, excited by a waveguide iris and the cavity perturbation technique was employed. The 16451B Vector Network Analyzer was used to measure the resonance frequency shift when the cavity is loaded with the material sample. For validation, the coaxial probe technique was used, through Dielectric Probe 85070 software. Results were presented for soils collected at different depths. The results show that the permittivity has small variation with depth, being higher in the shallower layers, with more organic matter. It was also verified a variation of the dielectric loss of the soil with the depth and variable with the frequency, indicating that it is possible to identify soil properties through the measurement of the dielectric properties.

The paper analyzes the main photophysical processes involving excited phosphor and oxygen molecules and reveals the relationship between the oxygen concentration and the integrated luminescence intensities in the absence and presence of oxygen. It is shown that the implementation of the method based on the measurement of the energy characteristics of luminescence can be brought to instrumentation by using a relatively simple measuring technique. In addition, a description is given of available devices for measuring the concentration of oxygen in liquid and gaseous media based on optical methods, and also their disadvantages are identified. A device is proposed for the quantitative determination of the antioxidant activity of a sample by oxygen concentration based on the integrated luminescence intensities of the luminescence in the absence and in the presence of oxidized oxygen. The structural diagram and principle of operation of the proposed device are illustrated. The results of the work can be applied in determining the antioxidant activity of food products.

A dual-band dual circularly polarized wide-angle scanning array, operational in the K/Ka bands is presented. A stacked-patch element, which is excited by two ports to provide left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) for TX and RX, respectively, is connected with active modules as part of a co-aperture phased array system. A sub-array composed of 2×2 sequentially rotated elements is designed to improve array's polarization purity and symmetry of radiation pattern. A 36-element (3×3 subarray) array prototype has been fabricated, which measured results exhibits good agreements with simulations. The circularly polarized bandwidths of the array are 7.8% at frequency point in first band and 5.3% at frequency point in second band, respectively. A maximum of 60° wide-angle scanning is also achieved at Dual-band frequency bands.

The capability to precisely rotate the cells and other microscale objects is invaluable in biomedicine, bioengineering, and biophysics. We propose a novel on-chip three-dimension (3D) cell rotation method using whirling flows generated by oscillating asymmetrical microstructures. In an acoustic field excited by the vibration of a piezoelectric transducer, two different modes of microvortices are generated around our custom-designed microstructures that are utilized to precisely achieve in-plane and out-of-plane rotational manipulation of microparticles and cells. The rotation mechanism is studied and verified using numerical simulations. We also investigate the effect of various parameters on the acoustically induced flows such as the frequency, the driving voltage and the distance from the microstructure tip to the oocyte center, thus indicating the rotational speed can be effectively tuned on demand for single-cell studies. Finally, by observing the maturation stages of M2 after excluding the first polar body of operated oocytes, the proposed method is proved noninvasive. Comparing with the conventional works, our acoustofluidic cell rotation approach is simple-to-fabricate and easy-to-operate, thereby allowing rotations irrespective of the physical properties of the specimen under investigation.

We review the state of the art of slotted waveguide array antenna technology. Design and analysis techniques of slot arrays in standard rectangular waveguides are discussed first. Subsequently slots cut in ridge waveguides, iris excited waveguides, strip lines, radial waveguides and gap waveguides are addressed. Some applications of slot arrays and manufacturing techniques are also briefly reviewed.

A design of wideband dielectric resonator antenna at 26 GHz for 5G communication applications is proposed in this paper. Square shaped slots of two different sizes are introduced in the DRA to reduce the quality factor (Q-factor); thus, to achieve wide bandwidth. The microstrip feed line is used to excite the DRA. The proposed antenna structure has achieved a bandwidth of 3 GHz (11.5 %) from 25 GHz to 28 GHz and a peak gain of 4.8 dBi with a radiation efficiency of 93%.

With the latest progress in new generation of phosphor and packaging design, full spectrum, sun-like white LEDs become possible. We have developed such light sources by using a 410nm violet chip to excite a set of phosphors of blue, cyan, green and red, and then fine tune the spectrum power distribution (SPD). High color quality properties such as Ra of 98, Rg of 98 and Rf of 100 were achieved. With CCT of 5000K, it has an efficiency >105lm/W, a spectral continuity Cs >85 and low blue hazard ratio Br

Optical frequency combs including microresonator-based ones can be used in telecommunications as multi-carrier sources in wavelength-division multiplexing. We produced samples of silica fiber-based spherical microresonators potentially interesting for this application. Whispering gallery modes were excited by broadband spontaneous emission radiation of an Er:fiber laser source. Q-factors were estimated. We also investigated theoretically the possibility of using silica-based Ge $\mathrm {O}_{2}-$ doped glass microspheres for comb generation in the dissipative soliton regime pumped at 1550 nm. It was shown numerically that optical frequency combs with a spectral width from E-band to L-band can be obtained for microspheres doped with 20 mol.% $\mathrm {G}\mathrm {e}\mathrm {O}_{2}$.

The emission properties of single-photon sources (a) attached to photonic nanostructures in the weak and strong coupling regimes have been intensively studied. However, often new opportunities arise in physical systems that operate at intermediate regimes between the more studied extreme cases. Here, we analyze the emission properties of a two-level system coupled to a two-mode cavity. Our analysis demonstrates that there is an intermediate regime, between the weak and strong coupling regimes, which offers an additional degree of freedom in controlling the bandwidth of a single-photon source, even when it is incoherently excited. In turn, this degree of freedom can be harnessed to decouple efficiency and bandwidth, thus bringing additional flexibility in the design of efficient photon sources with (b) controllable bandwidth.

This paper puts forward the forthcoming technology in military impact especially in the stealth operation. Synthetized ferrite phase $B_{a}F_{e}(M_{n}C_{o})_{1}.{}_{5}T_{i_{1.5}}O_{19}$ using sol-gel method as RAM (Radar Absorber Material) is analyzed to avoid detection from radar by coating it on military vehicle and weaponry. FTIR (Fourier Transform Infrared) is an analytical technique applied to identify organic and some cases of inorganic materials. The measurement technique of infrared absorption radiation is applied upon the sample material versus wavelength, because each molecule absorbs infrared radiation at its characteristic frequencies. When $B_{a}F_{e}(M_{n}C_{o})_{1}.{}_{5}T_{i_{1.5}}O_{19}$ as Irradiated infrared Radar Absorber Material, the absorbed radiation process normally stimulates each molecule into a higher vibrational state. The absorbed light wavelength by one particular molecule is the energy gap function between the at-rest and excited vibrational states. Proposed issues of embedded FTIR sensor for detecting $B_{a}F_{e}(M_{n}C_{o})_{1}.{}_{5}T_{i_{1.5}}O_{19}$ as RAM in UAVs with 5G network architecture by means of high frequency spectrum would be the next frontier of military impact as it enables significantly faster speeds to process a large amount of data with lower latency and greater device connectivity.

The concept of imperfection is always associated to a negative outlook. However, real devices are always imperfect and operate far from ideality. Despite this, real devices actually work. This is due to the fact that imperfections give rise to hidden dynamics, which can be excited to gain a positive effect on the overall behavior of the device. Human-machine systems are relevant examples of imperfect systems in which the presence of imperfections plays a crucial role, either negative or positive. In this paper, we focus on a paradigmatic example of imperfect systems, represented by a complex and imperfect electromechanical structure which supports and couples 15 coils rotating thanks to the electromagnetic interaction with associated magnets. The electrical and mechanical interaction between the coils and that between the coils and the structure generate complex patterns of vibration which may prevent the system from reaching the correct working conditions, i.e., all coils actually rotating. A control strategy to ensure coils rotation based on the excitation of the hidden dynamics induced by imperfections is discussed, characterizing its effect with respect to the control signal properties and to the power provided to the structure. It is worth to notice that the control strategy is essentially based on the excitation rather than on the suppression of the hidden dynamics, thus providing evidence on the possibility to control imperfect systems exploiting imperfections.

This paper presents, a dual-segmented Rectangular dielectric resonator antenna (RDRA) fed by a modified conformal strip for wideband application is proposed. $TE_{1,\delta,1}^{y}$ and $TE_{1,4,1}^{y}$ modes have been excited which show well-balanced radiation pattern and decent radiation efficiency throughout the bandwidth. The proposed antenna geometry is wideband in nature i.e. 4.32-7.27 GHz. Simulated gain of 7.04 dB was observed at 4.88 GHz while 5.46 dB was observed at 6.66 GHz. It can be concluded that the presented antenna is suitable for WLAN application (5. 15-5.835 GHz), Amateur Satellite (5.6 GHz), Microwave radiometry and various applications in 4-7 GHz frequency band.

Results for assessing the effects of mutual coupling on important array parameters such as directivity and bandwidth are presented for examining tradeoffs. A linear, equispaced 25 element dipole array was chosen as a test model to obtain results for uniform, Dolph-Chebyshev and Taylor amplitude distributions. A closed-form formula for the directivity, excluding mutual coupling, was derived to facilitate the computations for the arbitrarily excited, equispaced dipole array. The information gleaned from the results suggests that array mutual coupling, effected by inter element spacings, has significant impact on array directivity but does not similarly affect the array bandwidth. The influence of the scan angle and sidelobe level on the array bandwidth and directivity, for different excitations, have also been reported.

In this paper, a fractional order representation and the related hardware realization of the Duffing system are presented. The considered system can be defined as the general case of the standard Duffing system, which is a typical example of a non autonomous chaotic system. The aim of this paper is to confirm that an opportunely excited fractional order Duffing system, with order less than two, can have a chaotic behavior. This statement is supported with the circuital implementation of the circuit.

Methods for improved energy trapping of the thickness shear mode (TSM) in quartz crystal microbalances (QCMs) under lateral field excitation (LFE) are presented. The dependencies of TSM resonant intensity and spurious mode presence on surface curvature and electrode geometry are analyzed for improved LFE QCM response. TSM resonance trend data are given for 6 MHz plano-convex uncoated wafers and electroded devices up to 6 diopters (D). The energy trapping concept is also extended to include electrical energy redistribution, which alters the active acoustic modes in LFE devices. Aspects of data on newly discovered metal-loaded LFE shear modes more intense than known LFE TSMs are presented. Variations of these metal-loaded device responses with surface curvature and metal layer thickness are reported. Butterworth-Van Dyke (BVD) equivalent circuit parameters are extracted for air- and metal-loaded response comparisons. The observed influences of acoustic and electrical energy trapping expand knowledge on the extent of LFE device capabilities and reveal implications for resonator applications.

Helicon plasma is excited by RF power through helical antenna. Typical circuit consists of RF generator operating at 13.56 MHz and matching elements for coupling RF generator and antenna. The absorption of the RF power strongly depends on variable loading by high-density helicon discharge. The study of the typical double helical antenna and RF generator in the range of 13.56-700 MHz coupling and coupling optimization is presented in the paper. It is found that matching circuit for frequency of 13.56 MHz provides bandwidth of ± 0.5% at -10 dB. The double helical antenna has the resonant frequency of 525 MHz. Coupling optimization allow to reduce operating frequency down to 434 MHz. Frequency bandwidth can be extended up to ± 5% at -10 dB.

The paper analyses the excitation efficiency of the TE01 wave in a segment of the circular waveguide that is made in the center of one of the mirrors of the open resonator (OR) with the help of the higher order modes ТЕМ11q (in the Lagerr-Gauss functions) and TEM30q (in the Hermite-Gauss functions) and the degenerate mode TEM*11q. All calculations were carried out taking into account the vector nature of the electric field. The analysis results established that the maximum excitation efficiency of the TE01 wave in a circular waveguide using the TEM11q mode is 0.161. The excitation efficiency of the same wave using the TEM30q oscillation is equal to 0.121. When the considered wave was excited by using only the central part of the TEM*11q mode (in the Lagerr-Gauss functions) the maximum excitation efficiency of the TE01 wave grew up to 1. The maximum excitation efficiency of the same wave with the help of the central part of the TEM*11q oscillation (in the Hermite-Gauss functions) is slightly lower and amounts to 0.954. The amplitude distribution of the field of the considered wave takes the form of a ring in the mirror of the OR.

In this paper, the substrate integrated waveguide (SIW) slot array antenna using metasurface for cube satellite operating in the C-band was simulated. The antenna is sandwiched structure arranging a $2 \times 5$ periodic square conductor patch on the substrate integrated waveguide. As the surface wave excited in the SIW slot array propagates on the metasurface, additional resonance occurred and the impedance matching was better than the conventional antenna. The overall size of the final antenna was ${\mathrm {6.75cm\times 2.35cm\times 0.37 cm}} (1.07\lambda_{0}\times 0.37\lambda_{0}\times 0.06\lambda_{0}$ at 4.74 GHz). The simulated results have a bandwidth of 4.73-4.87 GHz (3.38%) satisfying the condition of |S11

Cerenkov luminescence (CL) is a novel imaging modality that has recently been used in biomedical imaging field. However, there are plenty of limitations for the clinical transactions of Cerenkov luminescence imaging (CLI), due to the properties of CL. The newly developed europium-doped gadolinium oxide (Gd 2 O 3 :Eu) nanoparticles can interact with the CL and γ-radiation as well, generating a stronger red-shifted light, which is of great benefits for biomedical application and clinical transaction.

Indocyanine green (ICG) is a water soluble anionic tricarbocyanine dye which has been widely used for biological applications. The photodegradation and aggregation of ICG were studied in aqueous solution by absorbance spectrum measurements. Two excitation wavelengths were used: 780 and 808 nm. The photodegradation analysis was performed based on the number of absorbed photons and rate equations of the electronic excited states. The aggregation effect is influenced by the solvent medium. A third emission band at 640 nm, observed when in PBS solution, could be observed, associated with a trimeric band. The degradation of the aggregated forms does not follow the Beer-Lambert law. The photodegradation rates were distinct between the two excitation wavelengths, showing distinct photodegradation behaviors.

A process for producing fluorescent Carbon Nanodots from sugarcane syrup is reported. The syrup is processed in a domestic microwave oven for 1.5 min, filtered and centrifuged, resulting in an orange stable suspension of nanoparticles capable of emitting visible (green) fluorescence when irradiated by ultraviolet (254 nm). The particles present dimensions ranging from 2 to 6 nm with distribution centered at ~5 nm, and maximum fluorescence intensity at 448 nm (violet) when excited at 360 nm. This work presents a green, fast and low-cost methodology for the obtention of luminescent carbon nanoparticles, with potential applications on optoelectronics, biomedicine, photocatalysis and renewable energy sources areas.

We propose a tunable terahertz (THz) absorber design that utilizes a bulk Dirac semimetal (BDS)-based metasurface. The absorber consists of a BDS film with a periodic ring slot, dielectric layer, and fully reflective gold mirror. Simulations indicate that localized surface plasmon resonance is excited within certain regions close to the ring slot, leading to dipolar plasmon resonance of periodic arrays along the polarization direction, thereby producing resonant absorption. The BDS conductivity scales linearly with the Fermi level that can be tuned by bias application, enhancing the electromagnetic-field concentration and shrinking the effective current path, thereby blue-shifting the operating frequency within an ultrawideband. The thickness of the proposed design is significantly less than the resonant wavelength; therefore, the design yields an ultrathin metasurface absorber. This paper may lead to the investigations of the tunable metasurface device based on the BDS.

An excessively tilted LPFG-assisted surface plasmon polaritons sensor (Ex-TLPFG assisted SPP sensor) with ultrahigh sensitivity is proposed and numerically investigated using the finite-element-method-based full-vector complex coupled mode theory. We show that the SPP mode is transited (or excited) gradually from both the p-polarized TM $_{0,j}$ and EH $_{v,j}$ ( $v\geq 1$ ) modes, and hence, the proposed SPP sensor can be tuned to achieve strong resonance of either the degenerate TM $_{0,j}$ and EH $_{2,j}$ modes or EH $_{1,j}$ mode to optimize the sensitivity for analyte refractive index sensing. The results confirm that a transition point corresponding to the phase matching curve of the SPP mode is obtained, which can be used to predict the optimized grating period. By this approach, ultrasensitive SPP refractometric sensor can be obtained and the sensitivity can be further improved through a simple method: reducing the fiber cladding combined with an optimized grating period. We demonstrate that a giant sensitivity as high as $10100\,\text{nm}/\text{RIU}$ is achieved for the degenerate TM $_{0,32}$ and EH $_{2,32}$ modes (or $7400\,\text{nm/RIU}$ for the EH $_{1,32}$ mode). These appealing characteristics make the proposed Ex-TLPFG-assisted SPP sensor ideal for biochemical analyte sensing applications.

A dual-polarized antenna with omnidirectional radiation and high isolation performance is proposed in this paper. The proposed antenna consists of courtyard-shaped metal frame, feeding network, and metal background. Working mechanism of the proposed antenna is analyzed by the theory of characteristic modes. Two orthogonal polarizations can be achieved by utilizing the orthogonal current distributions on the courtyard-shaped metal frame. In order to obtain the horizontal-polarized mode, eight slots etched on the walls of the courtyard-shaped metal frame are excited. A feeding network is placed at the inner part of courtyard-shaped metal frame for a compact design. Measured results show that the proposed antenna can cover the impedance bandwidth of 1.80–2.81 GHz for both polarizations with their corresponding isolations better than 35 dB. A peak gain of 7 dBi and a gain ripple less than 3 dB in the horizontal radiation plane are achieved. The proposed antenna can be applied in the indoor wireless communication.

A symmetrical hybrid driving waveform (SHDW) is proposed in this paper, which includes a symmetrical saw-tooth driving waveform and a sinusoidal friction regulation waveform, and the sinusoidal friction regulation waveform is applied to the shrinkage period of the symmetrical saw-tooth driving waveform. In other words, the proposed SHDW can be achieved when the waveform symmetry of the hybrid driving method is 50%. The SHDW can effectively drive the designed symmetrical linear piezoelectric stick-slip actuator, and the motion direction is also easily regulated. The excitation principle of the actuator excited by the SHDW is explained in detail. A prototype is fabricated and the experimental investigations of the actuator characteristics are carried on. The higher velocity and the larger driving capacity are realized using by the SHDW relative to the asymmetrical hybrid driving waveform. Testing results show that the prototype excited by the SHDW can obtain the peak no-load speeds of 0.41 and 0.39 mm/s in the forward and reverse directions when the saw-tooth driving waveform voltage is 10 $\text{V}_{\text {p-p}}$ for 800 Hz and the sinusoidal friction regulation waveform voltage is 2 $\text{V}_{\text {p-p}}$ for 39 kHz. The step efficiencies can reach 92% and 90%. The driving capacities can reach 10.52 and 9.85 [(mm/s)g/mW] with the load of 70 g under the locking force of 0.1 N. The actuator excited by the SHDW will make it ideal for miniature information technology devices.

We demonstrate that in a gyrotron with strong external reflections, frequency jumping in a wide range is possible due to sequential excitation of axial modes in the gyroTWT regime. Within the frame of a time-domain model, the frequency tuning in the range of 202.3-206 GHz and the output power of 0.5 kW is shown, when modes with a number of axial variations from 1 to 10 are excited. The obtained parameters are suitable for the positronium spectroscopy in a Fabry-Perot resonator.

In present work the surface plasmon polariton resonance excitation by grating on the metal substrate has been researched. The peculiarities of the propagation and excitation of surface plasmon polariton waves on plane silver and gold surfaces using metallic and dielectric gratings were studied. It is shown that a strong magnetic field appears under resonance in structures with a silver and gold substrate at certain grating parameters. Therefore, it is appropriate to use such structures to study luminescence excited by magnetic-dipole interaction.

Ultra-broadband THz conductivities of doped monolayer graphene on PET substrate after photo-excitation at various optical pump fluence are investigated. THz conductivity corresponds to the intra-band transition of hot carriers decreases and deviates from the Drude-type frequency dependence as the pump fluence increases, indicating the broader carrier-energy distribution and energy dependent scattering. However, we found that the semi-classical Boltzmann transport theory with dominant carrier scattering mechanisms such as charged impurity and intrinsic optical phonon scattering with e-ph coupling strength from Density functional theory within GGA approximation failed to explain the hot carrier temperature dependence of THz conductivity spectra. This result suggests that the underestimation of e-ph coupling by DFT calculation and the importance of e-e interaction on the e-ph coupling.

Asymmetric dual-grating-gate InGaAs high-electron-mobility transistors (ADGG-HEMTs) are studied as plasmonic terahertz (THz) emitters. We experimentally observed THz emission from a fabricated device at 110K. The spectra showed a broadband resonant emission under low d.c. channel currents reflecting radiation decay of thermally excited plasmons. With increasing the current and longitudinal electric field the emission was enhanced in a narrower spectral range suggesting promotion of plasmonic instability. Its threshold behavior suggests the occurrence of plasmonic-boom-type instability.

We present the semianalytical design and experimental verification of a realistic – printed circuit board (PCB) – metagrating (MG) for anomalous refraction with near-unity efficiency. The design follows our previously reported analytical formalism [1]–[3], developed on the basis of [4], considering an array of four capacitively-loaded wires in one period $\Lambda=\lambda/(\sin\theta_{in}-\sin\theta_{out})$ [Fig. 1(a)], chosen such that only four Floquet-Bloch (FB) modes are propagating when the MG is excited from $\theta_{in}$ : two in transmission (direct ray and anomalous refraction) and two in reflection (specular and anomalous reflection) [3]. The formulation utilizes the degrees of freedom of the structure, namely, the four capacitor widths, and the respective horizontal and vertical offsets of the wires, to simultaneously enforce the design requirements: elimination of spurious FB modes using reactive loading [4], while minimizing induced currents (minimizing absorption) [1], [2]. As shall be presented, to yield fabrication-ready devices, we extend our previous derivation [2] to apply to multilayer PCB MGs, rigorously incorporating the dielectric substrate into the forward and backward scattering problem. This allows the entire design, up to the detailed PCB layout, to be completed without as much as a single run in a full-wave solver.

We present design and optimization of nanoarrays, which consist of metallic nanoparticles that possess plasmonic properties. Optimal two-dimensional arrangements of nanoparticles are found by using an optimization environment involving genetic algorithms and a three-dimensional full-wave solver based on the multilevel fast multipole algorithm. The nanoarrays are designed to provide maximum radiation at desired directions when they are excited via isotopic sources. The designed structures and their radiation characteristics are extensively investigated by considering various parameters, such as grid size, nanoparticle shape, distance between nanoparticles, and material. The results demonstrate the favorable radiation characteristics of the designs, as well as the capabilities of the optimization environment to design compact nanoarrays for beam-steering applications.

In this paper, a three-dimensional (3D) printed low-profile wideband antenna for the fifth generation (5G) indoor communications is proposed. To obtain a compact size and wide-beamwidth characteristics, a 3D printed folded annular electrical dipole is designed. Furthermore, a pair of orthogonal -shape strips excited by a 90°-phase difference are arranged in the gaps of vertical plates to acquire the dual-circular polarization (CP) feature. The feeding network that is composed of a modified 3dB-hybrid coupler is printed below the ground to provide wide band and 90°-phase difference traits. Simulated results show that a wide bandwidth of 3.3 GHz-5.0 GHz (41%) with stable gain of approximately 6 dBi can be achieved. Besides, a wide beamwidth of 110° in dual CP directions as well as a low-profile of 0.18 $\lambda_{0}$ can also be obtained.

A new regime of whistler wave propagation in a large laboratory unbounded uniform plasma has been identified. The wave exhibits interesting topological characteristics, has an elongated structure and exhibits feeble resonance and almost no obliqueness [1]. Conventionally, whistler waves are known to exhibit complex three dimensional features with both parallel and oblique propagation. However, the waves excited here show no such feature. These characteristics are attributed to the electron inertia effects [2] that starts playing a significant role in a regime where typical antenna dimension is comparable to the electron skin depth ( $d_{e}=c/\omega_{pe}$ ), the characteristic spatial scale length of electron-magnetohydrodynamics (EMHD) of which whistler waves are the normal linear modes. Exact nonlinear solutions also exist in the form of structures called electron vortices, as shown by several theoretical and computational works [14]. Such solutions exist when spatial scale length $\lambda\ \leq\ d_{e}$ and structures propagate in the form of vortices uninhibited by the surrounding plasma. However, no experimental proof exists till date. Our results have revealed that the waves or structures excited indeed have spatial scale length limited to the electron skin depth when antenna dimension is of that order. A possible physical model describing the processes is also given. However, the parallel propagation is dominated by the guiding field and highly elongated. In the presence of feeble external guiding field or no field, the whistlerization does not occur, finite Larmor radius effects start playing a role and wave is guided along the resultant complex field [3]. The wave energy gets distributed due to the interplay between electron inertia and Larmor radius effects and the wave scatters. The results are very interesting because they have paved way for future work on the excitation of pure electron vortices and studies related to their relevance to plasma turbulence.

This paper investigates novel fractional slot nonoverlapping winding hybrid excited (HE) machines with different consequent pole permanent magnet rotors. The HE machines with different rotor configurations are developed to retain the PMs and utilize the flux concentrating effect. They are comprehensively analyzed and compared by finite element (FE) method. The optimal current ratio between the field and armature windings is identified theoretically and the torque improvement ratio by hybrid excitation is demonstrated to show the benefits of the proposed topology. Finally, the prototypes with different rotor configurations are fabricated and tested to validate the analyses.

By employing the U-slot and feeding network, a low-profile aperture-coupled microstrip patch antenna (MPA) is proposed in this paper. Initial, by etching the U-slot on the patch, the second resonant mode is excited around the fundamental mode of the MPA. Then, a square open-loop resonator is introduced below the aperture-coupled MPA for bandwidth-enhancement, thus exciting the third resonant mode. Finally, this proposed MPA is simulated and discussed. The result shows this antenna has generated the bandwidth for $\vert \pmb{S_{11}}\vert \pmb{ of about 10.57% under radiation of triple-modes. Meanwhile, the antenna also obtains a stable radiation patterns and relative gain of about 5.258 dBi within the whole working band range.

In this paper, a symmetrical ultrathin power divider is proposed, which is excited by the specific flaring ground structure and transforms the quasi-TEM waves to TM waves. The proposed structure is composed by the input transmission part with double-row periodic holes printed on the middle stripline and single-row holes printed on the two branch striplines as two output channels, respectively. The measured results of the fabrication model are agree well with the simulated results and can have good applications in further.

We report a high-quality encapsulated graphene quantum dot that exhibits stable Coulomb diamonds and excited states with a spacing of 0.4 THz. We performed the first transport spectroscopy measurement under THz illumination of a large quantum dot. The photocurrent map allows to measure with high precision a non-linear chemical potential renormalization of the graphene electrodes via the interaction with the quantum dot states.

Stable and wide range THz waves are obtained from the chaotically oscillated multimode-laser diode excited photoconductive antennas. This system is chap system And. this THz wave is suitable for the spectroscopy. In this paper, it is applied to distinguish water and oil.

We simulate the generation of terahertz radiation by using photoconductive antenna excited by noise-like pulses (NLPs). Our simulation results show that the bandwidth of THz spectrum generated by NLPs is narrower than by mode-locked pulses which is from same laser system in the low frequency region. However, the spectrum generated by NLPs exhibits additional components extended to higher frequency, though the power is relatively low.

Terahertz Chemical sensor based on the hexagonal microstructure air holes in a free-standing Aluminum foil having a thickness $\sim $11 $\mu$ m has been designed by numerical simulations which is further optimized and fabricated by Computerized Numerical Control (CNC) drilling machine. Localized plasmons (LPs) excited at the air holes are used to demonstrate refractive index sensing for liquids. The proposed sensor would be a potential device for liquid sensing applications.

A technique has been developed for modeling XeCl-excilamps of a barrier discharge (halogen donor HCl) which takes into account the parameters of the emitter and the excitation system. Simulation of a XeCl barrier discharge excilamp based on HCl: Xe: Ne mixtures with a total pressure of 0,5-1 atm, excited by an LC circuit, was performed. The dependence of the radiation pulse energy and efficiency on the composition of the mixture, the parameters of the emitter and the excitation system is determined. An efficiency reach ~ 37%.

In this paper, we consider theory of self-organization of periodic coupled temperature and strain (TS) fields on surfaces of anisotropic (transversely isotropic) solids irradiated by laser pulses. Laser-induced thermal field is treated as consisting of "atomic point defects" of a crystalline lattice - thermal phonons. The self-organization of TS structures occurs due to strain-thermal instability associated with a strain-induced flux of thermal phonons. Using the non-local forms of constitutive equations, a synergetic model of the process is formulated and substantiated, based on self-consistent dynamic equations for temperature and atomic displacements fields of the elastic continuum. Dispersion equation for instability is obtained and analyzed. It is observed that the length of non-local defect-atom interaction has a significant effect on the characteristics (growth rate, period) emerging strain-temperature surface structures. The period of these structures is proportional to the intrinsic length parameter and has a nanometer scale