This letter proposes a novel simple planar circularly polarized (CP) frequency beam-scanning (FBS) antenna using slotline (SL) and spoof surface plasmon polariton (SSPP) structure. A new SL-SSPP slow-wave transmission line (TL) is initiated by periodically introducing orthogonal tilted corrugated grooves on both sides of the SL, which can generate orthogonal electric-field components in the same cross-section along the TL, and its dispersion characteristic can be flexibly adjusted. In order to excite an effective radiating mode from the propagating slow-wave mode, a simple double-sided tilted modulation method is devised to periodically modulate the SL-SSPP TL. Further, to obtain the CP characteristic, a π/2 phase displacement between the sinusoidal modulation structures on both sides of the TL is designed. The configuration of presented CP beam-scanning antenna owns the merits of simpler structure, low profile, and single dielectric layer. A prototype is manufactured and then tested to verify the proposed design. The experimental results con-firm that, within the 3-dB axial ratio (AR) bandwidth (from 7.2 to 8.35 GHz), the designed antenna achieves a 35° beam-steering range with CP characteristic. This antenna also realizes appropriate gain and radiation efficiency in the working band.

In this letter, a novel compact frequency beam-scanning antenna (FBSA) using composite waveguide based on folded half-mode substrate integrated waveguide (FHMSIW) and spoof surface plasmon polaritons (SSPP) is proposed. The novel composite FHMSIW/SSPP waveguide with compact size and high field-confinement is initiated by embedding dual SSPP structures into the FHMSIW. Its transmission characteristic has flexible features from both the FHMSIW and SSPP. To excite the radiation mode from the composite slow-wave waveguide, a simple single-sided sinusoidal modulation method is designed and used. In this way, the common open stop-band problem around broadside is effectively eliminated, and the beam-scanning range of the antenna can be flexibly designed without changing the modulation structure. The presented scanning antenna owns a compact size and a simple feeding network. The experimental results indicate that the proposed FBSA can achieve continuous beam scanning from backward to forward in a wide scanning range of 60° within a bandwidth of 7.7–10.1 GHz. The stable unidirectional radiation patterns and appropriate gains are also realized in the entire operating frequency band.

With the development of large gradient wells and horizontal wells, resistivity anisotropy has become an important concern. Most of the inversion problems encountered in geophysical applications are time-consuming. In this letter, we propose a novel approach based on deep learning (DL) to solve the time-consuming problem of the inversion of induction logging data in layered anisotropic formation. A deep neural network (DNN) architecture combined with an adaptive moment estimation (Adam) optimization algorithm is utilized. Batch normalization is used to accelerate the training convergence. Data sets are obtained from forward modeling in different anisotropic formations, by which the DNN is trained, validated, and tested. A series of experiments are carried out to test the accuracy, robustness, and speed of the inversion based on DL in the anisotropic formation. The experimental results indicate that the approach based on DL can achieve the inversion with high accuracy. Furthermore, the trained DNN model for the inversion is two orders of magnitude faster than the most commonly used nonlinear iterative algorithm that achieves the same inversion precision. The trained DNN model considerably reduces the inversion computation time without compromising accuracy. Moreover, the approach overcomes the defect of the dependence of the nonlinear iterative algorithm on the initial values. Our study has shown the promising potential of the approach based on DL for inverting the logging data in anisotropic formations that are difficult to quickly invert by the conventional method.

The out-coupling efficiency of planar organic light emitting diodes (OLEDs) is only about 20% due to factors, such as, the total internal reflection, surface plasmon coupling, and metal absorption. Two-dimensional periodic nanostructures, such as, photonic crystals (PhCs) and microlenses arrays offer a potential method to improve the out-coupling efficiency of OLEDs. In this work, we employed the finite-difference time-domain (FDTD) method to explore different mechanisms that embedded PhCs and surface PhCs to improve the out-coupling efficiency. The effects of several parameters, including the filling factor, the depth, and the lattice constant were investigated. The result showed that embedded PhCs play a key role in improving the out-coupling efficiency, and an enhancement factor of 240% was obtained in OLEDs with embedded PhCs, while the enhancement factor of OLEDs with surface PhCs was only 120%. Furthermore, the phenomena was analyzed using the mode theory and it demonstrated that the overlap between the mode and PhCs was related to the distribution of vertical mode profiles. The enhancement of the extraction efficiency in excess of 290% was observed for the optimized OLEDs structure with double PhCs. This proposed structure could be a very promising candidate for high extraction efficiency OLEDs.

In the finite-difference time-domain (FDTD) simulation of the Maxwell-Schrodinger system it is necessary to analyze multi-physics phenomena ruled by more than one governing equation. In this study, a novel approach was proposed to solve the hybrid simulation. Using fourth-order spatial differences for the whole system and third-order symplectic integrators for the Schrodinger equation, the simulation was high-order-accurate and energy-conserving. This hybrid simulation is well suited to study the long-term light-matter interaction between electromagnetic radiation and charged particles in the semi-classical regime and can save computer resources with large time steps and coarse spatial grids.

In this study, a novel frequency beam‐scanning (FBS) antenna based on composite substrate integrated waveguide/spoof surface plasmon polariton (SIW/SSPP) waveguide is proposed. The composite SIW/SSPP slow‐wave waveguide is designed by embedding a series of periodic subwavelength H‐shaped grooves on the top surface of the SIW. Its transmission characteristics own both the features from SIW and SSPP, and can be flexibly mansplained by tuning the key structural parameters. To convert the propagating composite slow‐wave mode into the radiation mode effectively, a new flexible digital modulation method with staggered metallic vias is proposed and used. The presented beam‐scanning antenna has a simple feeding structure, a single dielectric layer, and a compact volume of 0.75 × 8.55 × 0.015 λ ₀ ³ . A prototype of the antenna is fabricated and tested to verify its performance. The experimental results demonstrate that the proposed antenna can realise a continuous beam‐scanning angle of 49° in an operating bandwidth of 8.7–9.2 GHz with a high frequency‐scanning sensitivity (FSS) of 9.8 °/100 MHz ⁻¹ . Moreover, the measured results indicate that the antenna has high peak gain with an average level of 12.7 dBi, high radiation efficiency with an average level of 87%, and stable unidirectional radiation pattern in the working band.