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In this paper, we derive an upper bound on load-threshold of coded slotted ALOHA (CSA) for slot erasure channel (SEC) and that for packet erasure channel (PEC), respectively. In SEC, by exploiting the analogy between Gaussian elimination of solving linear equations and the iterative successive interference-cancellation (SIC) decoding procedure of CSA, we derive the upper performance bound for SEC. Subsequently, in PEC, utilizing density evolution to track the average probability of packet-decoded failure within the SIC decoding process, we obtain the upper bound for PEC. Moreover, we propose a numerical search algorithm of these bounds under a given calculating precision. The numerical results indicate that the asymptotic upper limit on load-threshold of CSA over SEC is always less than that over PEC with any given erasure probability and average transmission rate. [ABSTRACT FROM AUTHOR]

In order to resist periodic interfere in robot hardware or environment, a Runge–Kutta type discrete-time circadian rhythms neural network (RK-DCRNN) model is proposed, and investigated to plan the motion of redundant robot manipulators. To achieve the optimal control, a quadratic programming-based acceleration-level hybrid tri-criteria (ALHT) scheme is first designed, which simultaneously minimize the acceleration norm, torque norm, and joint-angle shift-free indices. Second, according to the neural dynamic design method, a continuous-time circadian rhythms neural network model is exploited, and then based on the Runge–Kutta numerical differential method, a discrete-time circadian rhythms neural network model is obtained. Third, the convergence of the proposed RK-DCRNN model is proved by detailed mathematical derivation. Fourth, comparative simulations and physical experiments verify that the proposed RK-DCRNN model can suppress the accumulation of position error in the motion planning of manipulators. [ABSTRACT FROM AUTHOR]

A quadratic programming based neural dynamic (QPND) controller design method is proposed for time-varying trajectory tracking of unmanned aerial vehicles (UAVs). Different from the traditional controller frameworks which only use pitch and roll angles to achieve the horizontal movement of the UAV, all the three attitude angles, i.e., roll, pitch and yaw angles, are applied for horizontal moving in this paper. There are at least three great superiorities of the proposed QPND controller. Firstly, three attitude angles can be coordinated control since the quadratic programming framework incorporates three attitudes. Secondly, the new framework enables the UAV to achieve the additional performance criteria or to perform subtasks. Third, the new controller can track time-varying trajectories due to neural dynamic approach. Specifically, the design process of the controller is divided into position controller design, attitude controller design and quadratic programming formulation. Finally, simulation experiments verify the feasibility and high efficiency of the proposed controller and its superiority compared with some state-of-the-art UAV controllers. [ABSTRACT FROM AUTHOR]

To make manipulators fulfill end-effector maintaining tasks, such as writing or drawing tasks in a complex environment, two hybrid multiobjective motion planing schemes, i.e., end-effector posture-maintaining and obstacle avoidance (hybrid PM-OA) schemes are proposed and investigated for wheeled mobile redundant robot manipulators. Specifically, the end-effector posture maintaining, obstacle avoidance, and joint physical limits are considered in a quadratic programming (QP) problem. With these two hybrid PM-OA schemes, the wheeled mobile robot manipulators can maintain its end-effector posture, avoid the obstacle and joint physical limits during executing end-effector tasks. The hybrid PM-OA schemes are finally formulated into a piecewise-linear projection equations (PLPEs) and solved by a recurrent neural network (RNN). Computer simulations are given to substantiate the effectiveness, accuracy, safety, and practicability of the proposed hybrid PM-OA schemes. Comparisons with other schemes and simulations further show that the proposed hybrid PM-OA schemes are more suitable for applications. [ABSTRACT FROM AUTHOR]

Hybrid and intermittent characteristics of the distributed energy resources (DERs) bring great challenges to the security control and economic dispatch (ED) of the microgrids. To bypass these hurdles, this article proposes a multiagent system-based integrated design of security control and ED to guarantee the effective and economical operation of the interconnected microgrids. First, a hierarchical control scheme is constructed by two-level unit agents, in which the switching control and dynamic regulation are fully implemented with the corresponding hybrid behaviors based on the differential hybrid Petri-net (DHPN) model. Based on the DHPN model, a novel dynamic ED integrated with security control is proposed to overcome the issues that cannot be solved in conventional models. Furthermore, to reduce the computational complexity and unified the mathematical model of the DERs, the inverter-based power control strategy is converted to a predictive control model which can be decomposed into several subsystems. In the optimization process, all the subsystems are implemented in a fully distributed, communication free, and rolling optimization manner based on the distributed model predictive control (DMPC). The validity of the proposed design is demonstrated according to the simulation results in case studies. [ABSTRACT FROM AUTHOR]

Varying-parameter recurrent neural network, being a special kind of neural-dynamic methodology, has revealed powerful abilities to handle various time-varying problems, such as quadratic minimization (QM) and quadratic programming (QP) problems. In this paper, a novel power-type varying-parameter recurrent neural network (PT-VP-RNN) is proposed to solve the perturbed time-varying QM and QP problems. First, based on the generalization of time-varying QM and QP problems, the design process of the PT-VP-RNN is presented in detail. Second, the robustness performance of the proposed PT-VP-RNN is theoretically analyzed and proved. What is more, two numerical examples are simulated to illustrate the robustness convergence performance of PT-VP-RNN even in a large disturbance condition. Finally, two practical application examples (i.e., a robot tracking example and a venture investment example) further verify the effectiveness, accuracy, and widespread applicability of the proposed PT-VP-RNN. [ABSTRACT FROM AUTHOR]

Two novel nonlinearly activated recurrent neural networks (RNNs) with finite-time convergence [called finite-time RNNs (FTRNNs)] are proposed and analyzed to solve efficiently time-varying systems of nonlinear equations (SoNEs). Compared with previously presented neural networks for solving such a SoNE, the FTRNNs are activated by new nonlinear activation functions and thus possess a better finite-time convergence property. In addition, theoretical analyses about FTRNNs are presented to determine the upper bounds of convergence time under the context of using such two novel nonlinear activation functions. Computer simulations based on a numerical example validate the preponderance of the proposed FTRNNs for time-varying SoNE, as compared to the recently proposed Zhang neural network and its improved version. Finally, an engineering practical example to motion tracking of a robot manipulator demonstrates the feasibility and applicability of the FTRNNs. [ABSTRACT FROM AUTHOR]

To stably control the position and attitude angles of an unmanned aerial vehicle (UAV), a varying-parameter convergent neural dynamic (VP-CND) method is proposed and applied. First, the dynamic models of multirotor UAVs are presented. Second, to meet the requirements of high accuracy and real-time control, a VP-CND method is proposed based on an error function to derive the position and attitude angle controllers. The existing fixed-parameter CND methods (e.g., the triple-Zhang dynamics or the Zhang dynamics and gradient dynamics) and the corresponding controllers are presented, and their limitations are analyzed. The proposed VP-CND control method not only can track time-varying target values but also possesses super-exponential convergence performance. Third, simulation comparisons verify the effectiveness, stability, and fast convergence of the VP-CND controllers. [ABSTRACT FROM AUTHOR]

Sufficient pumping speed and good pumping performance should be guaranteed for the HL-2M tokamak. In order to provide sufficient pumping capacity, two in-vessel cryopumps will be installed at outer floor and ceiling, respectively. Pumping performance of HL-2M in-vessel cryopump has been estimated by direct simulation Monte Carlo program and test particle Monte Carlo program under free molecular flow condition. The predicted pumping speeds of each bare cryopump are 51.29 m3/s for H2, 38.04 m3/s for D2, and 24.94 m3/s for He. An advanced divertor system will be installed, located on the floor of the HL-2M vessel. When the conductance of the divertor is taken into account, the pumping speeds of the floor ring are 20.11 m3/s for H2, 15.14 m3/s for D2, and 12.50 m3/s for He. This shows that the effective pumping speed of the cryopump is greatly affected by the conductance of the divertor. A parametric study has been carried out, allowing the sticking coefficients of some different gases to vary within a +/−0.05 range with respect to the corresponding reference values. The results indicate that the He pumping speeds may be significantly affected by a small change of the sticking coefficient, while negligible effects are predicted to occur, as far as H2 and D2 are concerned. The results of the dynamic evaluation of the pumping process indicate that the cryopump has a quick time response. [ABSTRACT FROM AUTHOR]

An air-filled long slot leaky-wave antenna (LWA) based on folded half-mode waveguide (FHMW) fabricated using silicon substrate is proposed for millimeter-wave application. As is well known, the high-permittivity silicon dielectric is not suitable for antenna design. Thanks to the through-wafer dry etching and gold-plating processes deriving from the silicon bulk micromachining technology, three purely air-filled structures including the vertical part of the FHMW that also acts as the leaky-wave long slot in the top layer, horizontal part of the FHMW and matching section in the middle layer, and coupling slot in the bottom layer constitute the high-performance air-filled long slot LWA. To the best of the authors’ knowledge, this is the first time that an FHMW is adopted for antenna design. Compared with the conventional half-mode waveguide, the profile is lowered, the required silicon layer number is fixed to three, and the design can be more flexible. Experiment of the fabricated prototype shows that the main beam can be scanned from 41° to 49° with a gain variation between 13.15 and 15.41 dBi in the frequency range from 56 to 64 GHz. Moreover, confirmation of the design strategy provides the feasibility to realize the system-in-package solution. [ABSTRACT FROM AUTHOR]

A new antenna structure is proposed to show that a single-layer magnetic current array based on the microstrip line structure can achieve a relatively uniform and large in-phase radiating aperture together with high realized aperture usage rate (RAUR). By alternatively and periodically loading the microstrip line with blocking stubs, the equivalent magnetic currents along one direction are suppressed while the currents along the other direction are left, forming a relatively uniform and in-phase 1-D magnetic current array. The electromagnetic wave is radiated into space while traveling forward along the line. By in-parallel concatenating a series of the 1-D arrays with adjacent arrays presenting mirror relations, a large in-phase radiating aperture is built with a relatively high RAUR performance. Moreover, the shorting walls at the interconnecting planes of the neighboring 1-Darrays can be removed attributing to the antenna arrangement style and the required feed network. Eight rows of the 24-element 1-D magnetic current array fed using a substrate integrated waveguide-based eight-way power divider fabricated using a single substrate board is simulated and built to demonstrate the design strategy. The prototype shows a measured bandwidth of 4.37% and a peak gain of 25.1 dBi at 20 GHz. The RAUR is 8.66/ \lambda 0^{2} , which is higher than most of the single-layer high-gain antennas. [ABSTRACT FROM PUBLISHER]

In this paper, a 60-GHz air substrate leaky-wave antenna based on microelectromechanical system (MEMS) bulk micromachining is proposed. Using penetration dry etching and gold plating processes, the air-filled leaky-wave slots, waveguide, and coupling slot, which are located in the top, middle, and bottom silicon-based layers, respectively, are generated. The three layers are stacked and clamped together using two location pins and five metal screws. The most distinctive feature of the proposed antenna is that the electromagnetic wave cannot see any substrates, except for the air medium, leading to good antenna performance. Good agreement between simulation and measurement demonstrates that the MEMS micromachining process fulfills the millimeter-wave (mm-wave) accuracy. To the best of the authors’ knowledge, this is the first time that an air substrate mm-wave antenna is fabricated using the MEMS bulk micromachining technology. The fabricated prototype with a bandwidth of 17.3% and a peak gain of 11.4 dBi is attractive for mm-wave wireless communication applications. Validity of the feasibility provides the possibility to realize the system-in-package solutions. [ABSTRACT FROM AUTHOR]

A triangular-cavity-cascaded antenna is proposed and analyzed for wideband applications. By alternatively and periodically shorting a metallic plate on its edges with small slices, isosceles-triangular field patterns are generated and cascaded for wideband antenna design. Synchronous electric edge fields which contribute to radiation occupy almost all the areas of both sides of the plate. Compared with a typical microstrip antenna with a rectangular cavity, the triangular-cavity-cascaded antenna is a relatively open structure with less shorting boundary around. As a result, the quality factor is smaller, and the impedance bandwidth is wider. In order to prove the design strategy, a 1-D cascaded antenna with $1 \times 5$ triangular cavities and a 2-D cascaded antenna with $2 \times 5$ triangular cavities are fabricated and tested. Experimental results show that the impedance bandwidths of 1-D and 2-D antennas are 35.66% and 21.43%, while the peak gains are 13.27 and 16.47 dBi, respectively. [ABSTRACT FROM AUTHOR]

In this communication, an all-metal standing wave antenna array is proposed based on the microstrip transmission line. By alternatively blocking the microstrip line every half wavelength, the symmetrical equivalent magnetic currents are broken for effectively radiating. By properly tuning the blocking positions along the microstrip line, a broadside pattern is achieved with high gain. The proposed antenna is scalable along one direction to a certain level to acquire the directivity as high as about 15 dBi. More importantly, the proposed antenna array has the potential to be built only by metal without any dielectrics. The all-metal structure has the merits of being low-cost, light weight, easily fabricated, and having no dielectric losses. Based on this idea, a five-segment linear array with a center feed is designed and tested. The measured bandwidth is from 7.83 to 8.81 GHz (980 MHz, 11.78%), and the measured gain is ranging from 9.1 to 12.47 dBi. [ABSTRACT FROM AUTHOR]

A six-beam switched beam antenna (SBA), whose beam patterns are shaped in the azimuth plane, is designed and fabricated. A synthesis method, which is based on a four-elements array and can generate a flat-top beam pattern with 46° flat gain region (gain fluctuation within \pm \mathbf0.5\,\mathbfdB), 60° 3-dB beam width, and less than - \mathbf20.1\,\mathbfdB side lobe level (SSL), is proposed. By combining six of those beams together, the proposed SBA can provide near consistent gain and good interference rejection in the azimuth plane. Meanwhile, an interleaving array architecture, which minimizes the size of the proposed array, is also implemented. To extend the beam coverage, a series-fed in-phase array with tapered amplitude distribution is introduced in the elevation plane. The peak gain of the beam reaches 16.6 dB, and the SLL is controlled under - 23.2\,\mathbfdB in this plane. [ABSTRACT FROM PUBLISHER]

This communication proposes a wideband differential-fed slot antenna that works in its dominant mode (\lambda/2 mode). The antenna has a near omnidirectional radiation pattern with vertical polarization, which is designed for near-ground wireless sensor node applications. A compact integrated T-slot balun and a loop to T-slot feeding structure are introduced to realize the differential feeding; the bandwidth is expanded to 30.7% (2.2 GHz–3.0 GHz) with a 3.8 dB peak gain. A detailed matching method without using lumped elements is proposed, which can be applied to various types of RFIC chips. A prototype is built and measured. Its differential impedance, antenna patterns, and gain are consistent with the simulation results. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel scheme to improve the signal-to-noise ratio (SNR) response of the main beam nulling for small-scale adaptive arrays. This method effectively promotes the main-beam nulling performance by introducing a displaced element at the end of an adaptive array. It is easy to implement with very low system cost. A detailed analysis of its working mechanism is provided, and the performance is verified with the simulation results. A switching scheme is introduced further to realize consistent performance for all nulling regions, which can attain similar main beam nulling performance as a larger-scale adaptive array. Combining with the active element pattern method, the performance of the proposed scheme involving mutual coupling is examined with a dipole array. It is consistent with the results acquired in isolated condition, which verifies its feasibility in practice. [ABSTRACT FROM PUBLISHER]

In this communication, a dual-polarized diversity antenna with azimuthally omnidirectional patterns is designed inside a slender and low-profile columnar structure. The proposed antenna is composed of a cavity-backed notch for horizontal polarization and a folded slot for vertical polarization. The most important contribution of this communication is to reduce the antenna dimension, maintain high port isolation, broaden impedance bandwidth, and generate azimuthally omnidirectional radiation patterns. The overall volume of the proposed antenna is 42\times 12\times 12\ mm^3 (0.336\lambda0\times 0.096\lambda0\times 0.096\lambda0). A prototype of the proposed antenna is built and measured for 2.4-GHz wireless local area network (WLAN) applications to validate the idea. [ABSTRACT FROM PUBLISHER]

This communication proposes a dual-polarized slot antenna array, which is able to expand two-dimensionally (2-D), using only one layer of substrate board. Two identical coplanar waveguide (CPW) series-fed slot arrays are positioned orthogonally, providing dual polarization with high port isolation. The overall array is arranged on both sides of a single substrate, achieving low cost in fabrication. To validate the design concept, a model of the proposed array is built for the 2.4-GHz wireless local area network (WLAN) application. We have measured S parameters, radiation patterns and gain, and compared them with the simulation results. [ABSTRACT FROM PUBLISHER]

A novel null scanning patch antenna operating at 2.4 GHz is presented. Unlike the existing reconfigurable techniques, the even and odd modes of a shorted patch are adopted to first achieve a broadside pattern and pattern null on broadside. Continuous null scanning is achieved by combining these two modes with different exciting powers. The mechanism of null scanning is discussed from both theoretical analysis and simulated/measured results. A rat-race switching network is used to excite the two modes and simultaneously obtain high port isolation. A prototype is fabricated and tested. The measured results verified the null scanning capability of the proposed design. [ABSTRACT FROM PUBLISHER]

In this paper, we have proposed a co-located and folded slots antenna for multiband applications. The proposed antenna consists of three radiating slots, arranged on a compact square columnar structure. By properly tuning the dimensions and the positions of the co-located slots, the proposed antenna operates in penta-band, including DCS, PCS, UMTS, 2.5-GHz, and 3.5-GHz WiMAX bands. Additionally, omnidirectional radiation patterns are provided in the azimuthal plane for all the operating bands. The overall volume of the proposed square columnar antenna is only 50\,\times\,10\,\times\,10 mm^3, which is suited for volume-limited systems. A prototype of the proposed antenna is fabricated and tested, to validate the design idea. The measured data, including S parameter, radiation pattern, and gain, agree well with the simulation results. [ABSTRACT FROM PUBLISHER]

A dual circularly polarized waveguide antenna with bidirectional radiations of the same sense is proposed in this communication. Bidirectional circular polarization (Bi-CP) of the same sense was obtained by two identical rectangular metal slices installed on one lateral side of the waveguide with an intersection angle of 45^\circ. These two metal slices were horizontally perpendicular to each other and vertically spaced by a quarter guided wavelength. A rat-race coupler was employed to excite the two metal slices with the same amplitude, but with a 0^\circ or 180^\circ phase difference depending on the selection of two inputs. One sense of Bi-CP was realized when the two metal slices were fed in phase and the opposite sense of Bi-CP could be obtained when they were fed out of phase. A prototype for 2.4-GHz WLAN application was tested to verify our design. The measured common bandwidth for 10-dB return loss and 3-dB axial ratio at the two feed ports was 230 MHz (9.6%, 2.29–2.52 GHz) and 210 MHz (8.6%, 2.35–2.56 GHz), respectively. The measured isolation between the two feed ports was better than 30 dB over the whole operating band. [ABSTRACT FROM AUTHOR]

In this communication, a novel approach to expand the bandwidth for the ultra-low profile wearable shorted patch is proposed and fabricated. It introduces dual-resonance to acquire 5.2% bandwidth within 0.358\lambda \times 0.358\lambda \times 0.011\lambda dimension at 430 MHz without increasing the structure complexity. By using EVA (ethylene-vinyl acetate) foam and copper gauze as the material, this dual-resonant shorted patch is light, flexible, and rigid enough for wearable application. SAR (special absorption rate) and performance after bending are simulated and analyzed to validate its reliability in wearable condition. The measurement result verifies the design concept, which can provide consistent radiation character, along with acceptable gain and efficiency in the whole working band. [ABSTRACT FROM PUBLISHER]

This paper presents the successful design and physical realization of a wideband MNG-TL dipole antenna. An artificial mu-negative transmission line (MNG-TL) structure is realized by employing periodically loaded parallel-plate lines. It is known that the current reversal, which occurs at frequencies much beyond the dipole natural frequency, disturbs the omnidirectional radiation pattern in the azimuth plane. The MNG-TL has a unique property to support a zero propagation constant (\beta =0) with non-zero group velocity at the zeroth-order resonance. Due to the unique property of an infinite wavelength, the current distribution of the dipole antenna can be improved. Furthermore, the MNG-TL dipole is also useful to achieve a wide impedance bandwidth. A prototype of the proposed MNG-TL dipole is fabricated and measured. It can provide a wide effective bandwidth of about 1.55 GHz (1.85–3.40 GHz) with VSWR 2:1 (S11< -10 dB) impedance matching and stable omnidirectional radiation patterns in the azimuth plane. [ABSTRACT FROM PUBLISHER]

This communication presents a new 4-port feeding structure with sequential phase (SP) of 0^\circ, 90^\circ, 180^\circ and 270^\circ using a circularly polarized (CP) shorted loop. A 2\,\times\,2 single-fed circularly polarized corner-truncated patch array is connected to the loop's four shorting strips, which serve as 4 feeding ports with stable phase difference. By using the proposed SP feed, the axial ratio (AR) bandwidth of the array is increased to more than 7%, wider than the previous design. A prototype of the proposed antenna is built to validate the design experimentally, and a global bandwidth of 4.86–5.12 GHz is achieved (S11 <-10 dB, AR < 3 dB, and gain variation within 3 dB). [ABSTRACT FROM PUBLISHER]

An omnidirectional dual-polarized antenna with high port isolation is presented for 2.4-GHz wireless local area network (WLAN) applications. The omnidirectional patterns of both vertical and horizontal polarizations in the azimuthal plane are achieved by positioning two orthogonal slots cut onto the walls of a slender columnar cuboid. The overall volume of the proposed antenna is only 83\times 11\times 11~\mm^3~(0.664\lambda0 \times 0.088\lambda0 \times 0.088\lambda0), with low mutual coupling between two radiating slots. A prototype of the proposed antenna is fabricated and tested. The measured results show that the 10-dB reflection coefficient bandwidths of dual polarizations cover the desired band of 2.4–2.48 GHz and the port isolation is lower than -33.5 dB. Stable gains are greater than 3.17 and 1.19 dBi for vertical and horizontal polarizations, respectively. The diversity performance is also evaluated, including the correlation coefficient, mean effective gain (MEG) ratio, and diversity gain. [ABSTRACT FROM PUBLISHER]

In this paper, a cyclic-motion generation (CMG) scheme at the acceleration level is proposed to remedy the joint-angle drift phenomenon of redundant robot manipulators which are controlled at the joint-acceleration level or torque level. To achieve this, a cyclic-motion criterion at the joint-acceleration level is exploited. This criterion, together with the joint-angle limits, joint-velocity limits, and joint-acceleration limits, is considered into the scheme formulation. In addition, the neural-dynamic method of Zhang is employed to explain and analyze the effectiveness of the proposed criterion. Then, the scheme is reformulated as a quadratic program, which is solved by a primal–dual neural network. Furthermore, four tracking path simulations verify the effectiveness and accuracy of the proposed acceleration-level CMG scheme. Moreover, the comparisons between the proposed acceleration-level CMG scheme and the velocity-level scheme demonstrate that the former is safer and more applicable. The experiment on a physical robot system further verifies the physical realizability of the proposed acceleration-level CMG scheme. [ABSTRACT FROM AUTHOR]

A novel periodic leaky-wave antenna for broadside radiation with horizontally polarized omnidirectional pattern is proposed, designed and demonstrated experimentally. The objective is to achieve a horizontally polarized omnidirectional antenna array with highly directive beam. The proposed structure is based on combining the rotating electric field method and a leaky-wave antenna design. By properly designing a unit cell with a pair of crossed dipoles spaced at a distance approximately equal to \lambdag/4 at the center frequency, not only omnidirectional radiation pattern with horizontal polarization is obtained by crossed dipoles fed in phase quadrature, but also the open-stopband effect exhibited at broadside scan is significantly reduced. The analysis and design of this structure are performed on the basis of a simple equivalent network model. A finite structure formed by 16-unit cell (32-element) for broadside beam is developed at the 2.4 GHz band, which offers a horizontally polarized omnidirectional radiation pattern with enhanced gain of 9.9–10.6 dBi and measured radiation efficiency of 90% for the covering bands. [ABSTRACT FROM PUBLISHER]

A horizontally polarized omnidirectional planar loop antenna that employs an artificial mu-negative transmission line (MNG-TL) is proposed. The MNG-TL is designed using periodically loaded parallel-plate lines. The reactive loading is inspired by the zeroth-order resonator (ZOR), which has a propagation constant of zero. Due to the unique property of an infinite wavelength, the MNG-TL loop antenna presented in this paper allows current along the loop to remain in phase so that a horizontal polarized omnidirectional pattern is generated. A series-fed array, which is composed of four MNG-TL loop antennas and operates at 2.4 GHz band, is designed, fabrication, and measured. The MNG-TL loop antenna array offers a horizontally polarized omnidirectional radiation pattern with enhanced gain of 6.5 \sim 7.9 dBi and measured radiation efficiency exceeding 85% for covering bands. The concept extends the degrees of design freedom for horizontally polarized omnidirectional antenna array. [ABSTRACT FROM PUBLISHER]

A compact monopole-slot antenna with polarization diversity is proposed for wireless local area network (WLAN) applications. Dual polarization is provided by a ground-folded monopole and a slot cut from the folded ground. The total volume of the proposed antenna is only 50\,\times\,16\,\times\,16 mm^3\ (0.4 \lambda0 \times 0.128 \lambda0 \times 0.128 \lambda0). However, low mutual coupling is achieved due to the orthogonal modes of current distribution on the ground. A prototype of the proposed antenna is built and tested. The obtained results include the S parameters, radiation patterns and radiation gain. The results from our presentation match with the simulation and demonstrate an isolation better than -36 dB in the required band. [ABSTRACT FROM PUBLISHER]

A folded loop-inverted F reconfigurable antenna for mobile phone applications is designed and the obtained results are discussed in this communication. It is shown that loop antenna mode and an inverted F antenna (IFA) mode are controlled by only one p-i-n diodes with simple bias circuit. The impedance can be matched by adopting a matching bridge for both the loop and IFA modes. In a compact volume of 60\,\times\,5\,\times\,5 mm^3, the proposed antenna operates in hepta-band, including GSM850, GSM900, GPS, DCS, PCS, UMTS and WLAN, with the return loss lower than 6 dB. A prototype of the proposed antenna is fabricated, measured, and obtained results including return loss, efficiency and gain, are presented. [ABSTRACT FROM PUBLISHER]

A wideband antenna with a reconfigurable coplanar waveguide (CPW)-to-slotline transition feed is proposed for pattern diversity applications. The feed provides three modes -CPW feed, left slotline (LS) feed and right slotline (RS) feed- without extra matching structures. Changes between modes are controlled by only two p-I-n diodes. Features of the proposed switchable feed include compact size and simple bias circuit. The equivalent transmission line model is used in the analysis of the proposed design. A prototype of the proposed antenna is fabricated, tested, and the obtained results including reflection coefficient, radiation patterns and gains, are present. A measurement of channel capacity is carried out to prove the benefit of pattern diversity when using the proposed antenna in both line-of-sight (LOS) and non-line-of-sight (NLOS) communication scenarios. [ABSTRACT FROM AUTHOR]

A conformal switchable antenna system mounted on a cylindrical surface is proposed, simulated, prototyped and measured. The antenna system is composed of several tri-polarization antennas operating at 2.4 GHz band. It is shown that this antenna system realizes a quasi-isotropic pattern without any nulls over a complete spherical surface. Specifically, it is shown that by using three tri-polarization antennas and switching among them, a complete spherical coverage could be achieved without any nulls and with a power gain larger than 2.5 dBi over more than 90 percent of a spherical surface surrounding the antenna system. Furthermore, it is shown that the performance of the antenna system does not deteriorate with the increase in the diameter of the mounting cylinder, thus facilitating the implementation of the proposed design in many applications including telemetry, satellites, and aircraft. Both simulation and experimental results of the radiation patterns are presented in this paper. [ABSTRACT FROM AUTHOR]

A novel compact wideband antenna, which adopts a multi-state switchable matching circuit, is proposed in this paper. The design of the switchable matching is systematically studied and a two-step iterative procedure is used to obtain optimized values for both the bandwidth division between the various stages and the matching circuit components in each stage. Without loss of generality, a meander line monopole, with dimensions of 80\,\times\,10\,\times\,10 mm^3, is used as the radiator in the proposed wideband antenna design. To validate the proposed new design, a four-state matching circuit controlled by four PIN diodes is fabricated and measured. The reflection coefficient of the prototype antenna is found to be better than -7.3 ~dB, and the peak gain is higher than -3 ~dBi across the 470–770 MHz bandwidth for the Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) application. [ABSTRACT FROM PUBLISHER]

A dual-band dipole antenna for wireless local area network (WLAN) is designed and experimentally tested at both the 2.4 and 5 GHz (IEEE 802.11b/g and 802.11a) WLAN bands. The design procedure involves obtaining a full resonance frequency in the 2.4 GHz band and then using a matching network to achieve a secondary resonance at the 5 GHz band. It is shown that by correctly designing the dipole, the matching network can be simplified to only one series inductor. The design was experimentally verified by constructing a dipole on a FR4 board (12 mm *45 mm * 0.45 mm) and measuring its input impedance and the radiation characteristics at both bands. The measured VSWR 2:1 bandwidth in the 2.4 GHz band is 710 MHz, and the bandwidth in 5 GHz band is wider than 1 GHz. The VSWR 3:1 bandwidth is more than 3.6 GHz and it coven from 2.32 GHz to above 6 GHz. it is significant that the designed dual-band dipole maintained good radiation efficiency values at both bands. Specifically, and based on the measured radiation patterns, an efficiency value of 85% ∼ 87% is obtained at 2.4 GHz and a value in the range of 55 ∼ 64% is obtained in 5 GHz band. [ABSTRACT FROM AUTHOR]

In this communication, we present a longitudinally slotted substrate integrated slot (SIS) leaky-wave antenna (LWA) for point-to-point communication. To mitigate the dispersion of traditional substrate integrated waveguide (SIW) LWAs, an SIS is proposed by etching a long straight slot along the SIW. The loaded slot mitigates the dispersion of SIW due to the special electric field distribution. Anti-TE10 mode is excited inside the SIS. Then, longitudinal slots are symmetrically loaded on both sides of the long slot. The prototype of SIS LWA is validated by the simulated and experimental results. A frequency bandwidth of 10.3% is realized with the beam squinting within 7° and realized gain of 13.9 ± 0.7 dB at a fixed angle of −7°. The proposed antenna is intended for point-to-point communication. [ABSTRACT FROM AUTHOR]

In this article, the repetitive motion control of redundant manipulators is investigated. First, a repetitive motion control scheme is presented, and a continuous zeroing neural network (CZNN) model is obtained for solving the scheme. Meanwhile, the development of a discrete zeroing neural network (DZNN) model is desired for convenient computational processing. Based on this, this article proposes a 6-step discretization formula, which has high precision. By using the 6-step discretization formula and the 4-step backward difference formula, a 6-step DZNN (6SDZNN) model is further proposed to handle the repetitive motion control scheme. Theoretical analyses verify the efficacy of the 6SDZNN model. Additionally, some discrete forms of conventional models are developed for comparison. Computer simulations on the basis of the 4-link redundant manipulator are carried out, verifying the theoretical analyses and showing the efficacy of the 6SDZNN model. Finally, physical experiments on the basis of the Kinova Jaco2 manipulator substantiate the practicability of the 6SDZNN model. [ABSTRACT FROM AUTHOR]

This article demonstrates an electronically scanned reflectarray antenna based on liquid crystal (LC). The LC-based reflectarray element was designed as a periodically loading of parallel H-shaped polygons on two metal layers. To realize a tunable reflection phase and reduce the inhomogeneity effect of LC, an $8~\mu \text{m}$ -thick LC layer was designed as a varactor rather than a substrate. In simulations, the adjustable reflection-phase range of the proposed element was 180° in the frequency band 21–21.5 GHz. The design concept was verified on a reflectarray prototype containing 26 rows of the basic elements. In addition, a 32-channel control circuit was designed and fabricated for biasing. The measured results confirmed a tunable phase range of 150° at 23.8 GHz. The disagreements between the simulated and measured results are discussed, and a test process is proposed. As a proof of concept, the main beam was steered to 0°, −40°, and −60° in one plane. The result confirmed the high beam-steering capability of the proposed reflectarray with measured gains above 18 dB at 23.8 GHz. This work provides useful references for the design and measurement of LC-based reflectarray antennas. [ABSTRACT FROM AUTHOR]

This article describes a compact dual-polarized endfire antenna array for fifth-generation (5G) millimeter-Wave (mm-Wave) mobile application. The dual-polarized endfire antenna element is constructed by a compact open-ended cavity with cavity mode for vertical polarization (VP) radiation and open-slot mode for horizontal polarization (HP) radiation. With the integrated design of VP and HP elements, the proposed antenna shows a much more compact size compared to existing schemes. To enhance the bandwidth of low-profile VP radiation, a slot is etched on the cavity to create a new mode for dual-resonance response, realizing a wide bandwidth of 24.5–29.5 GHz for both polarizations. In addition, radiation pattern modification techniques are employed to achieve good endfire beams with a high front-to-back ratio for both polarizations, thus enabling a high peak gain of 10.3 and 11.3 dBi for VP and HP, respectively. A wide beam scanning range of ±50° with realized gain above 7 dBi is realized at 27 GHz for both polarizations. In virtue of compact size, wide bandwidth, high gain, and good spatial coverage, the proposed design strategy is promising for future 5G mm-Wave mobile phones. [ABSTRACT FROM AUTHOR]