Journal articles: 'Antenna Pointing Mechanism'

1

TSUKADA, Eiichi, Shigeki OGAWA, and Susumu SAKANO. "An antenna pointing mechanism for communication satellites." Transactions of the Japan Society of Mechanical Engineers Series C 52, no. 481 (1986): 2416–20. http://dx.doi.org/10.1299/kikaic.52.2416.

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Li, Xin, Xilun Ding, and Gregory S. Chirikjian. "Analysis of a mechanism with redundant drive for antenna pointing." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 2 (November 13, 2016): 229–39. http://dx.doi.org/10.1177/0954410016636157.

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Orientation accuracy is a key factor in the design of mechanisms for antenna pointing. Our design uses a redundantly actuated parallel mechanism which may provide an effective way to solve this problem, and even can increase its payload capability and reliability. The presented mechanism can be driven by rotary motors fixed on the base to reduce the inertia of the moving parts and to lower the power consumption. The mechanism is redundantly actuated by three arms, and is used as a two-dimensional antenna tracking and pointing device. Both the forward and inverse kinematics are investigated to find all the possible solutions. Detailed characters of the platform are analyzed to demonstrate the advantages in eliminating singularities and improving pointing accuracy. A method of calculating the overconstrained orientational error is also proposed based on the differential kinematics. All the methods are verified by numerical examples.

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Kornienko, Andrei, Robert Wuseni, and Bernhard Specht. "System Identification of a Spacecraft Antenna Pointing Mechanism." IFAC Proceedings Volumes 46, no. 19 (2013): 172–77. http://dx.doi.org/10.3182/20130902-5-de-2040.00057.

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Kumar, Anish, and Thangadurai N. "Laser Based Real Time Antenna Pointing Measurement System." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 28. http://dx.doi.org/10.14419/ijet.v7i3.12.15857.

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The antenna pointing system is very important to obtain an optimum received signal level. To achieve it, presenting the implication of laser beam radiated emission requirements and how they state for pointing measurement system, its impact on design, verification and testing for the antenna pointing system. The antenna pointing system is developed by using array of linear light sensors, crosshair laser weapon, where the light sensors are mounted on the board and laser weapon putted on the antenna mechanism. On the rotator system, composed by using 2 gears and 2 DC motors with customized frames. For collecting the sensors data using ProASIC3 FPGA fabric and finding the numbers and which sensors has been active during the emitting period and 32-bit ARM Cortex-M3 processor take account into the pointing measurement system to computing the pointing and pointing error. At the end, the final step is building a User Graphical Interface on PC to show the output of the antenna pointing.

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Mar, J., K. C. Tsai, Y. T. Wang, and M. B. Basnet. "Intelligent Motion Compensation for Improving the Tracking Performance of Shipborne Phased Array Radar." International Journal of Antennas and Propagation 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/384756.

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The shipborne phased array radar must be able to compensate the ship’s motion and track the maneuvering targets automatically. In this paper, the real-time beam pointing error compensation mechanism of a planar array antenna for ship’s motion is designed to combine with the Kalman filtering. The effect of beam pointing error on the tracking performance of shipborne phased array radar is examined. A compensation mechanism, which can automatically correct the beam pointing error of the planar antenna array, is proposed for shipborne phased array radar in order to achieve the required tracking accuracy over the long dwell time. The automatic beam pointing error compensation mechanism employs the parallel fuzzy basis function network (FBFN) architecture to estimate the beam pointing error caused by roll and pitch of the ship. In the simulation, the models of roll and pitch are used to evaluate the performance of beam pointing error estimation mechanism based on the proposed parallel FBFN architecture. In addition, the effect of automatic beam pointing error compensation mechanism on the tracking performance of adaptive extended Kalman filter (AEKF) implemented in ship borne phased array radar is also investigated. Simulations find out that the proposed algorithms are stable and accurate.

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Merriam, E. G., J. E. Jones, S. P. Magleby, and L. L. Howell. "Monolithic 2 DOF fully compliant space pointing mechanism." Mechanical Sciences 4, no. 2 (December 2, 2013): 381–90. http://dx.doi.org/10.5194/ms-4-381-2013.

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Abstract. This paper describes the conception, modeling, and development of a fully compliant two-degree-of-freedom pointing mechanism for application in spacecraft thruster, antenna, or solar array systems. The design objectives and the advantages of a compliant solution are briefly discussed. Detailed design decisions to meet project objectives are described. Analytical and numerical models are developed and subsequently verified by prototype testing and measurements in several iterations. A final design of the 3-D printed titanium monolithic pointing mechanism is described in detail and its performance is measured.

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Zhang, Xin, Shijie Liu, Haifeng Yu, Xiaohua Tong, and Guoman Huang. "EFFECT OF ANTENNA POINTING ERRORS ON SAR IMAGING CONSIDERING THE CHANGE OF THE POINT TARGET LOCATION." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-3 (April 23, 2018): 267–71. http://dx.doi.org/10.5194/isprs-annals-iv-3-267-2018.

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Towards spaceborne spotlight SAR, the antenna is regulated by the SAR system with specific regularity, so the shaking of the internal mechanism is inevitable. Moreover, external environment also has an effect on the stability of SAR platform. Both of them will cause the jitter of the SAR platform attitude. The platform attitude instability will introduce antenna pointing error on both the azimuth and range directions, and influence the acquisition of SAR original data and ultimate imaging quality. In this paper, the relations between the antenna pointing errors and the three-axis attitude errors are deduced, then the relations between spaceborne spotlight SAR imaging of the point target and antenna pointing errors are analysed based on the paired echo theory, meanwhile, the change of the azimuth antenna gain is considered as the spotlight SAR platform moves ahead. The simulation experiments manifest the effects on spotlight SAR imaging caused by antenna pointing errors are related to the target location, that is, the pointing errors of the antenna beam will severely influence the area far away from the scene centre of azimuth direction in the illuminated scene.

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TSUKUDA, Eiichi, Yoichi KAWAKAMI, Shojiro MIYAKE, and Shigeki OGAWA. "On-board antenna pointing mechanism for multi-beam satellite communications systems." JSME international journal 30, no. 270 (1987): 2011–17. http://dx.doi.org/10.1299/jsme1987.30.2011.

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TSUKADA, Eiichi, Yoichi KAWAKAMI, Shojiro MIYAKE, and Shigeki OGAWA. "On-board antenna pointing mechanism for multi-beam satellite communication system." Transactions of the Japan Society of Mechanical Engineers Series C 53, no. 489 (1987): 1047–52. http://dx.doi.org/10.1299/kikaic.53.1047.

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YIN, Kang-cheng, Qiang YONG, Yin-long HUO, Xiao-guang XIE, and Xiao-dong LI. "Design of deployable biaxial pointing mechanism for spaceborne dual-reflector offset antenna." Optics and Precision Engineering 29, no. 3 (2021): 582–91. http://dx.doi.org/10.37188/ope.2020.0548.

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11

Yang, Guoyong, Hongguang Wang, Jizhong Xiao, Zuowei Wang, and Lie Ling. "Research on a Hierarchical and Simultaneous Gravity Unloading Method for Antenna Pointing Mechanism." Mechanical Sciences 8, no. 1 (March 20, 2017): 51–63. http://dx.doi.org/10.5194/ms-8-51-2017.

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Abstract. This paper presents a hierarchical and simultaneous gravity unloading method. An air bearing gravity unloading facility for two-orthogonal-axis antenna pointing mechanism (APM) is designed based on this method. This method is proposed based on the characteristics analysis of the two-orthogonal-axis APM and air bearings. The mechanism of the hierarchical and simultaneous gravity unloading method is described in detail. It solves the coupling problem of two axes and unloads the gravity of both joints hierarchically and simultaneously. The air bearing gravity unloading facility which is a structure mechanism with two layers based on this method is designed with planar air bearing and air spindle. The structure of the facility is described in detail. The dynamic models of the APM with its load in space environment and on the air bearing gravity unloading facility are derived respectively. With the analysing of the driving torques and vertical forces of the APM joints in both models, the results demonstrate that the gravity unloading facility can simulate the microgravity environment successfully. This conclusion is also proved by the dynamic simulation with ADAMS software. The simulation also provides some optimization targets for the gravity unloading facility. At last, the gravity unloading facility is established and some experiments are done. The dynamic models, the simulation results and the experiments all show the effectiveness of the hierarchical and simultaneous gravity unloading method.

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12

Pei-yuan, Xu. "Design of Chinese Second 25-m VLBI Antenna." Symposium - International Astronomical Union 129 (1988): 477. http://dx.doi.org/10.1017/s0074180900135302.

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The first Chinese 25-m VLBI antenna has just been completed at the She-Shan Station of the Shanghai Observatory. In accordance with the plan of the Chinese VLBI Network, the second 25-m VLBI antenna will be established at the Urumqi VLBI Station. It is a shaped symmetric dual reflector Cassegrain antenna and will be equipped with nine feeds from 0.3 GHz to 23 GHz. The surface accuracy of the main reflector is 0.65 mm, and the 14-m central part has a better surface accuracy (0.42 mm) to provide the possibility of making VLBI observations at 44 GHz. This antenna has a semihomology design, and its subreflector has a mechanism to focus it in three dimensions. Crossed dipole feeds for the 0.32 and 0.61 GHz bands are located in the middle of the subreflector, and the focussing mechanism will retract it to bring the dipoles to the prime focus. For other frequencies, a corrugated horn will be mounted at the Cassegrain focus. To obtain dual frequency operation at X and S bands, a flat dichroic reflector and an elliptical reflector will be mounted over the on-axis S band horn and off-axis X band horn, respectively. The antenna has a wheel and track mounting, and the pointing will be controlled by an IBM PC/XT microcomputer. The pointing and tracking accuracy is 16 arcsecond. The estimated aperture efficiencies are in the range of 45–65%. The estimated antenna temperatures are in the range of 35–100 K.

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13

Eom, Sangcheol, Byeongsu Kang, Hyunsop Kim, Inyong Park, Yeonyong Kim, Kyuhun Hwang, Woong Choi, Seunguk Yang, and Hyunwoo Lee. "Development and Evaluation of Dual-Axis X-band Antenna Pointing Mechanism for Space Applications." Journal of the Korean Society for Aeronautical & Space Sciences 46, no. 5 (May 31, 2018): 410–18. http://dx.doi.org/10.5139/jksas.2018.46.5.410.

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14

Han, Jianchao, Lei Liang, and Yang Zhao. "Dynamic Performance of Planetary Gear Joint for Satellite Antenna Driving Mechanism Considering Multi-Clearance Coupling." Energies 14, no. 4 (February 4, 2021): 815. http://dx.doi.org/10.3390/en14040815.

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Dynamic pointing and tracking accuracy are the most relevant indicators of dynamic performance for the satellite antenna driving mechanism. Multi-clearance coupling in the joints will incur high-frequency vibration and dynamic errors of the system. Joints of existing analytical models are generally oversimplified as planar revolute hinges, which ignore the coupling effect of multi-clearance. It cannot proficiently predict the dynamic behavior of the driving mechanism with multi-clearance on the orbit. To address this problem, a typical 2K-H planetary gear joint model with multi-clearance coupling has been developed by considering radial clearance, backlash, tooth profile error, time-varying meshing stiffness, and damping. A dynamic model of a typical dual-axis driving mechanism is established to analyze the dynamic characteristics of multibody systems with planetary gear joints. The effects of rotational speed, radial clearance, backlash, and their coupling on the dynamic performance of the dual-axis driving mechanism under different driving modes are explored by numerical simulations. The results show that the coupling of radial clearance and backlash in joints have a significant influence on the dynamic performance of the system. Appropriate clearance design avails the dynamic pointing accuracy and tracking accuracy of the dual-axis driving mechanism.

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15

Zheng, Tao, Zheng Fei, Xi Rui, and Lide Yan. "A Novel Space Large Deployable Paraboloid Structure with Power and Communication Integration." International Journal of Antennas and Propagation 2019 (November 13, 2019): 1–17. http://dx.doi.org/10.1155/2019/3980947.

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The combination of a solar array and a communication antenna can reduce the entire mass, physical size, and cost in space applications. Currently, related studies mainly focus on the combination of the two structures on the one flat plate structure (FPS). Compared with the FPS, a paraboloid structure has a lower surface density and higher conversion efficiency. Therefore, a novel space large deployable paraboloid structure with power and communication integration (SSPCI) is proposed and designed in detail, for spacecraft on a sun synchronous earth orbit; it consists of a cable mesh membrane reflector (CMMR), an energy conversion device (ECD), and a three-extensible-rod (TER) pointing mechanism. To achieve the goal of integrating power and communication, the TER pointing mechanism drives the CMMR/ECD to track the sun in the sunshine region or to turn to face the ground station/other target in the Earth’s shadow region. Then, through simulation analyses of the deploying process, static force at a limit orientation, and sun tracking process of the SSPCI, it is proved that the SSPCI is feasible and has satisfactory performance. Finally, deploying experiments of the folded hoop of the CMMR and sun tracking experiments of the TER pointing mechanism on the ground were carried out successfully, which proves that the folded hoop can be deployed successfully with fairly high deploying dependability, and the TER pointing mechanism is feasible for the SSPCI from the mechanism principle and the control mode in space applications indirectly. Moreover, the tracking accuracy of the TER pointing mechanism is estimated to be within ±0.4° although the machining precision of its components is not high.

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She, Yuchen, Shuang Li, Yinkang Li, Liu Zhang, and Shuyi Wang. "Slew path planning of agile-satellite antenna pointing mechanism with optimal real-time data transmission performance." Aerospace Science and Technology 90 (July 2019): 103–14. http://dx.doi.org/10.1016/j.ast.2019.04.028.

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17

Drews, R., O. Eisen, D. Steinhage, I. Weikusat, S. Kipfstuhl, and F. Wilhelms. "Potential mechanisms for anisotropy in ice-penetrating radar data." Journal of Glaciology 58, no. 209 (2012): 613–24. http://dx.doi.org/10.3189/2012jog11j114.

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AbstractRadar data (center frequency 150 MHz) collected on the Antarctic plateau near the EPICA deep-drilling site in Dronning Maud Land vary systematically in backscattered power, depending on the azimuth antenna orientation. Backscatter extrema are aligned with the principal directions of surface strain rates and change with depth. In the upper 900m, backscatter is strongest when the antenna polarization is aligned in the direction of maximal compression, while below 900 m the maxima shift by 90° pointing towards the lateral flow dilatation. We investigate the backscatter from elongated air bubbles and a vertically varying crystal-orientation fabric (COF) using different scattering models in combination with ice-core data. We hypothesize that short-scale variations in COF are the primary mechanism for the observed anisotropy, and the 900 m boundary between the two regimes is caused by ice with varying impurity content. Observations of this kind allow the deduction of COF variations with depth and are potentially also suited to map the transition between Holocene and glacial ice.

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Liang, Wei, Jin Huang, and Jie Zhang. "A New Adaptive System for Suppression of Transient Wind Disturbance in Large Antennas." International Journal of Antennas and Propagation 2019 (September 4, 2019): 1–13. http://dx.doi.org/10.1155/2019/2015341.

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Under transient wind disturbance, vibration deformation of the large antenna surface profile causes deterioration of pointing performance. This paper presents a new adaptive system to suppress unknown transient wind disturbance. First, to monitor the vibration, based on the acceleration measurement and a low-order flexible model considering equivalent identification of forces, the real-time estimation of the vibration state is obtained in an unbiased minimum-variance way. Next, a novel four-cable-actuator mechanism with a circular slide track is proposed for suppressing the vibration, in which the locations of the cable drivers on the slide track are determined according to the attitude of the antenna, and the expected tension distribution of the cables is found by the vibration state and the optimal gain of the linear quadratic regulator (LQR). In the end, the simulation implementation of a 7.3 m antenna under the transient wind disturbance is used to verify the effectiveness of the proposed method.

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You, Bindi, Dong Liang, Yiming Sun, Xiangjie Yu, and Xiaolei Wen. "Numerical and experimental investigation on nonlinear dynamic behavior of satellite antenna reflector mechanism considering geometrical nonlinear effect and laminated composite material." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 233, no. 2 (October 11, 2018): 208–22. http://dx.doi.org/10.1177/1464419318803471.

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A nonlinear dynamic modeling method for a satellite antenna system composed of laminated composite shell reflector undergoing large rotation considering its geometrically nonlinear effect and material nonlinearity effect is proposed in this paper. The present model treats flexible appendages of a spacecraft mechanism as laminated composite material and takes into account the coupling relations between nonlinear constitutive relation of laminated material characteristics and large-angle maneuver. Then, the corresponding efficient formulations for laminated paraboloidal reflector based on higher order shear deformation theory and Hamilton's principle are developed to capture the correct dynamic response. Furthermore, the experiment for evaluating the dynamic behavior of laminated composite reflector is conducted; the vibration of the laminated composite material is smaller than that of isotropic material. Numerical results are in good agreement with those obtained from experiment to validate the correctness of the present modeling formulation. Finally, numerical simulations demonstrate that nonlinear stiffness terms and elastic force resulting from with different curvature and different laying angle have significant effect on the dynamic characteristics. The larger curvature of the reflector and the larger laying angle of the laminated composite material will induce the larger deformation of the reflector. The conclusion has important theoretical value and practical significance for the study of controlling the pointing behavior of satellite antennas.

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Su, Te Jen, Jui Chuan Cheng, Ming Yuan Huang, and Xun Xain Zhan. "A Hybrid PSO-PI Controller for the LEO Satellite Tracking System." Advanced Materials Research 912-914 (April 2014): 1069–72. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1069.

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This paper presents a smart-routing mechanism of a control system to track Low Earth Orbit (LEO) satellites. Satellite tracking mainly relies on the antenna pointing database generated by SGP4 orbit forecasting model and follow the point coordinates to command the rotation of the axes. Gears rotation gaps will affect the strength of the received signal; the Proportional Integral (PI) controller is used to adjust the error values caused by the drive shaft mechanism. Particle swarm optimization (PSO) algorithm has fewer parameter settings and the advantages of fast convergence, which is adopted for variable selection and optimization for the parameters kp and ki of PI controller. The resolver feedback mechanism of actual angle indicator is using as a basis for performance adjustment in the search process. The experimental results of a three axes tracking system demonstrate the reliability and better performance of the proposed PSO-PI satellite tracking system.

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Oh, Hyun-Ung, Su-Hyeon Jeon, Tae-Hong Kim, and Yong-Hoon Kim. "Experimental feasibility study for micro-jitter attenuation of stepper-actuated X-band antenna-pointing mechanism by using pseudoelastic SMA mesh washer." Smart Materials and Structures 24, no. 4 (February 24, 2015): 045010. http://dx.doi.org/10.1088/0964-1726/24/4/045010.

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22

Zhang, Jie, Jin Huang, Pengbing Zhao, Wei Liang, and Congsi Wang. "Antenna control systems for flexible structure under a wind load." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 9 (September 18, 2018): 3050–59. http://dx.doi.org/10.1177/0954406218802322.

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Higher levels of pointing (directional) accuracy are required with the increase of diameter of large reflector antennae. The influence of wind disturbance on the level of pointing error has become a serious problem with the increased size of antenna. Newer, larger antenna designs have to combine increased control and more accurate pointing mechanisms that challenge existing technology. With reference to the typical Cassegrain antenna, this paper aims to improve the accuracy of antenna pointing mechanisms under a variety of wind conditions. This is based on the pointing model derived from combining both structural dynamics and electromechanics such that the pointing error caused by wind can be estimated efficiently. Using different controller design methods, which present the flexible pointing error as a combination of rotation angle error, torque disturbance, and state disturbance, the pointing error is compensated effectively. Tests and analysis of a 7.3 m antenna have been conducted. The results show that the linear-quadratic-Gaussian controller can reduce the maximum pointing errors by 79.3%, and the sliding mode controller is found to significantly outperform other controllers as it has the smallest root mean square of pointing error.

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Zhang, Jie, Jin Huang, Wei Liang, Youran Zhang, Qian Xu, Letian Yi, and Congsi Wang. "A Correction Method of Estimating the Pointing Error for Reflector Antenna." Shock and Vibration 2018 (May 30, 2018): 1–12. http://dx.doi.org/10.1155/2018/3262869.

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The pointing error caused by the structural deformation of large reflector antennas has become the most challenging problem of antenna servo control. Especially with the increase of the antenna diameter and the working frequency, environmental loads not only make the structure deformation more obvious, but also make the pointing accuracy influenced by deformation more sensitive. In order to solve this problem, accurately estimating the pointing error caused by the structural deformation is the key. Based on the dynamic model of antenna structure and the analyzing model of pointing error, using the displacement information of sampling points on reflector, this paper proposes a correction method to achieve the purpose of accurately estimating the pointing error caused by the structural deformation. Using a 7.3-m Ka band antenna, the results show that the antenna maximum pointing error in theoretical model calculation is 0.0041° at 10m/s wind speed condition; however, the corrected pointing error would be about 0.0054° with considering the modeling error. After compensating the controller, the pointing error could be reduced to only 0.0008° and the performance of antenna pointing was improved.

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Senthil Kumar, S., and G. Anitha. "A Novel Self-Tuning Fuzzy Logic-Based PID Controllers for Two-Axis Gimbal Stabilization in a Missile Seeker." International Journal of Aerospace Engineering 2021 (January 13, 2021): 1–12. http://dx.doi.org/10.1155/2021/8897556.

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Tracking a target is an essential function of a seeker for missiles. The target tracking mechanism of a seeker consists of gimbals, mounted with gyroscopes, and an antenna or some other energy receiving devices such as radar, infrared (IR), or laser. Stabilization of such a gimbal is necessary for any guided missile to maintain the tracking device always pointing towards the target. For the stabilization of the gimbal system, several control methods have been employed for making the gimbal to follow an input rate command by eliminating all the gimbal disturbances. Here, a new self-tuning fuzzy logic-based proportional, integral, derivative (PID) controller is introduced for the stabilization of a two-axis gimbal for a manoeuvring guided missile. The proposed control method involves tuning the gains of the PID controller based on the fuzzy logic rule bases considering the missile body rotation. The performance of the stabilization loops has been verified through MATLAB simulations for fuzzy logic-based PID controller compared with the conventional PID controller. The simulation results show the response of the gimbal system with stabilization loops met the control requirements with fuzzy PID controllers but not with conventional PID controllers.

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Xie, Xin, Chao Qi, Ruoyu Tan, and Dapeng Fan. "Design and performance analysis of a many-to-one configuration precise cable drive mechanism with high precision and large torque." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 16 (May 15, 2019): 5903–15. http://dx.doi.org/10.1177/0954406219849450.

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Precise cable drive is a flexible frictional transmission method that transmits power from drive capstans to driven pulleys by a properly preloaded transmission medium. Since most of precise cable drive mechanism with high pointing precision proposed in previous studies suffer from low transmission stiffness and small output torque, this paper presents a novel many-to-one configuration precise cable drive mechanism (MCCDM) with high precision and large torque. The design methods of many-to-one configuration are studied including the system optimal design and cable wrapping design. The transmission characteristics of the developed configuration are analyzed, considering transmission capacity, transmission backlash, and transmission stiffness. The corresponding parameter sensitivities are also investigated. Moreover, a prototype of the MCCDM has been built, with which a series of experiments are carried out. It is noted that the developed mechanism has a motion range of ±2 rad. The steady-state error to a step reference of 1 rad amplitude is only 1.39 µrad and the position resolution is better than 0.5 µrad. This mechanism could achieve maximum output torque of 35 Nċm with compact size and light weight. It has reached a considerable toque-to-weight ratio of 8.997 N·m/kg. The experimental results show that the self-excited oscillation and backlash are dominant nonlinear effects in the MCCDM system. It shows that the self-excited oscillation is a function of the rotational displacement in such a system, with the highest peak at 0.1669 cycle/mrad and the amplitude of 34.63 µrad. The backlash could be measured about 60 µrad under exciting of a small amplitude and low frequency sinusoidal signal. The proposed technologies could have strong technological implications in some special applications such as antenna servo system.

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Gilmore, Rowan. "The world’s fastest wireless backhaul radio." Australian Journal of Telecommunications and the Digital Economy 3, no. 1 (April 27, 2015): 1. http://dx.doi.org/10.18080/ajtde.v3n1.2.

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Fibre is commonly perceived to be the dominant transport mechanism for transferring data from access points back to a central office, where it is aggregated onto the core network. However, high speed and long range wireless backhaul remains a cost-effective alternative to fibre networks. In some areas, wireless backhaul is dominant and becoming more and more attractive. However, commercially available wireless backhaul systems do not meet the requirements for both high speed and long range at the same time with sufficiently low latency for some applications. Traditional microwave systems can achieve long transmission range, but the data rates are then limited to a few hundred megabits per second. Multi-gigabit per second wireless communications can be achieved using millimetre-wave (mm-wave) frequency bands, especially in E-band, but the practical transmission range has then always been a major weakness.In this article, the world’s first 5Gbps radio solution – and the fastest commercial backhaul product – developed by EM Solutions Pty Ltd with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) – is described. As well as achieving a state-of-the-art data rate, other key design features include maximal path length, minimal latency, and constant antenna pointing under wind and tower vibration.

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Gilmore, Rowan. "The world’s fastest wireless backhaul radio." Journal of Telecommunications and the Digital Economy 3, no. 1 (April 27, 2015): 1–15. http://dx.doi.org/10.18080/jtde.v3n1.2.

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Fibre is commonly perceived to be the dominant transport mechanism for transferring data from access points back to a central office, where it is aggregated onto the core network. However, high speed and long range wireless backhaul remains a cost-effective alternative to fibre networks. In some areas, wireless backhaul is dominant and becoming more and more attractive. However, commercially available wireless backhaul systems do not meet the requirements for both high speed and long range at the same time with sufficiently low latency for some applications. Traditional microwave systems can achieve long transmission range, but the data rates are then limited to a few hundred megabits per second. Multi-gigabit per second wireless communications can be achieved using millimetre-wave (mm-wave) frequency bands, especially in E-band, but the practical transmission range has then always been a major weakness.In this article, the world’s first 5Gbps radio solution – and the fastest commercial backhaul product – developed by EM Solutions Pty Ltd with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) – is described. As well as achieving a state-of-the-art data rate, other key design features include maximal path length, minimal latency, and constant antenna pointing under wind and tower vibration.

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Wu, Qinhao, Yongqiang Cheng, Xiang Li, and Hongqiang Wang. "Beam Synthesis with Low-Bit Reflective Coding Metamaterial Antenna: Theoretical and Experimental Results." International Journal of Antennas and Propagation 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/5058789.

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Coding metamaterials are the new technology where the aperture coding provides the hardware foundation for the miniaturization of the devices. As a synthetic 2-D plane, metamaterial antennas are composed of subwavelength resonant particles. It can realize real-time control of electromagnetic wave and build multifunction radar array system. We make a detailed explanation of its array structure, working principle, and hardware system. However, it is usually difficult to synthesize flexible beams because the phase value is very limited in this antenna. Two methods are proposed in this paper to demonstrate the beam synthesis based on repetitive coding and convolution, and the distribution of beam pointings is analysed on the basis of this mechanism. Experiments that measure the radiation pattern of this antenna are carried out to verify the simulated results using only 1-bit coding metasurface in a radar system, whose phase value is controlled by pin diode on the surface.

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Huuskonen, Asko, Mikko Kurri, Harri Hohti, Hans Beekhuis, Hidde Leijnse, and Iwan Holleman. "Radar Performance Monitoring Using the Angular Width of the Solar Image." Journal of Atmospheric and Oceanic Technology 31, no. 8 (August 1, 2014): 1704–12. http://dx.doi.org/10.1175/jtech-d-13-00246.1.

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Abstract A method for the operational monitoring of the weather radar antenna mechanics and signal processing is presented. The method is based on the analysis of sun signals in the polar volume data produced during the operational scanning of weather radars. Depending on the hardware of the radar, the volume coverage pattern, the season, and the latitude of the radar, several tens of sun hits are found per day. The method is an extension of that for determining the weather radar antenna pointing and for monitoring the receiver stability and the differential reflectivity offset. In the method the width of the sun image in elevation and in azimuth is analyzed from the data, together with the center point position and the total power, analyzed in the earlier methods. This paper describes how the width values are obtained in the majority of cases without affecting the quality of the position and power values. Results from the daily analysis reveal signal processing features and failures that are difficult to find out otherwise in weather data. Moreover, they provide a tool for monitoring the stability of the antenna system, and hence the method has great potential for routine monitoring of radar signal processing and the antenna mechanics. Hence, it is recommended that the operational solar analysis be extended into the analysis of the width.

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Wang, Jing, Zhihua Wan, Zhurong Dong, and Zhengguo Li. "Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment." Machines 9, no. 1 (December 23, 2020): 1. http://dx.doi.org/10.3390/machines9010001.

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The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

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Liu, Quan, Sheng-Nan Lu, and Xi-Lun Ding. "An Error Equivalent Model of Revolute Joints with Clearances for Antenna Pointing Mechanisms." Chinese Journal of Mechanical Engineering 31, no. 1 (May 6, 2018). http://dx.doi.org/10.1186/s10033-018-0233-6.

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LI, Long, Shengnan LYU, and Xilun DING. "Dynamics modeling and error analysis for antenna pointing mechanisms with frictional spatial revolute joints on SE(3)." Chinese Journal of Aeronautics, May 2021. http://dx.doi.org/10.1016/j.cja.2021.04.008.

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Cui, Yaqi, Peng Lan, Haitao Zhou, and Zuqing Yu. "The Rigid-Flexible-Thermal Coupled Analysis for Spacecraft Carrying Large-Aperture Paraboloid Antenna." Journal of Computational and Nonlinear Dynamics 15, no. 3 (January 20, 2020). http://dx.doi.org/10.1115/1.4045890.

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Abstract Since the thermal load would adversely introduce degradation to the normal operation of spacecraft, resulting in unpredictable thermal-dynamic behavior, thermomechanical coupling problems are important and have been investigated extensively. Based on the absolute nodal coordinate formulation (ANCF), a thermal integrated ANCF thin plate element based on the unified description is constructed, which could depict the displacement and the temperature field integratedly. By means of the proposed element, the heat transfer and continuum mechanics are integrated in the unified finite element method (FEM) mesh of revolving paraboloid antenna. Additionally, the ANCF reference node is introduced for describing the rigid central hub where the antenna is mounted on to make the rigid-flexible-thermal coupled response being captured in a unified analysis procedure. The solar radiation input and the surface emitting radiation are included in the heat transfer equations. Furthermore, the influence of the rigid body motion and the deformation on the radiant absorption are also considered with the self-shadowing. The established rigid-flexible-thermal coupled simulation is performed on a modified generalized-α integrator which solves the set of multidisciplinary governing equations synchronously. For revealing the nonlinear behavior of the rigid-flexible-thermal coupled system, the observed thermally induced vibration and perturbation on the pointing accuracy of the spacecraft are given in the results, and the feasibility of the presented method is proved.

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Journal articles on the topic 'Antenna Pointing Mechanism'

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