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Journal articles on the topic 'Active load pull'

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Author: Grafiati

Published: 23 September 2022

Last updated: 27 January 2023

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1

Hashmi, M. S., A. L. Clarke, S. P. Woodington, J. Lees, J. Benedikt, and P. J. Tasker. "An Accurate Calibrate-Able Multiharmonic Active Load–Pull System Based on the Envelope Load–Pull Concept." IEEE Transactions on Microwave Theory and Techniques 58, no. 3 (March 2010): 656–64. http://dx.doi.org/10.1109/tmtt.2010.2040403.

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2

Ghannouchi, F. M., R. Larose, R. G. Bosisio, and Y. Demers. "A six-port network analyzer load-pull system for active load tuning." IEEE Transactions on Instrumentation and Measurement 39, no. 4 (1990): 628–31. http://dx.doi.org/10.1109/19.57245.

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3

Marchetti, M., M. J. Pelk, K. Buisman, W. Neo, M. Spirito, and L. de Vreede. "Active Harmonic Load–Pull With Realistic Wideband Communications Signals." IEEE Transactions on Microwave Theory and Techniques 56, no. 12 (December 2008): 2979–88. http://dx.doi.org/10.1109/tmtt.2008.2007330.

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4

Romier, M., M. Romier, M. Romier, A. Barka, H. Aubert, H. Aubert, J. P. Martinaud, and M. Soiron. "Load-Pull Effect on Radiation Characteristics of Active Antennas." IEEE Antennas and Wireless Propagation Letters 7 (2008): 550–52. http://dx.doi.org/10.1109/lawp.2008.2005652.

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5

Andersson, Christer M., Mattias Thorsell, and Niklas Rorsman. "Nonlinear Characterization of Varactors for Tunable Networks by Active Source–Pull and Load–Pull." IEEE Transactions on Microwave Theory and Techniques 59, no. 7 (July 2011): 1753–60. http://dx.doi.org/10.1109/tmtt.2011.2135377.

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6

Hone, Thomas M., Souheil Bensmida, Kevin A. Morris, Mark A. Beach, Joe P. McGeehan, Jonathan Lees, Johannes Benedikt, and Paul J. Tasker. "Controlling Active Load–Pull in a Dual-Input Inverse Load Modulated Doherty Architecture." IEEE Transactions on Microwave Theory and Techniques 60, no. 6 (June 2012): 1797–804. http://dx.doi.org/10.1109/tmtt.2012.2190748.

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7

Xie, Chengcheng, Shuman Mao, Gang Yu, Huanpeng Wang, Ruimin Xu, and Yuehang Xu. "A simplified active load-pull behavioral model for power amplifiers." IEICE Electronics Express 16, no. 20 (2019): 20190536. http://dx.doi.org/10.1587/elex.16.20190536.

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8

Poulin, D. D., J. R. Mahon, and J. P. Lanteri. "A high power on-wafer pulsed active load pull system." IEEE Transactions on Microwave Theory and Techniques 40, no. 12 (1992): 2412–17. http://dx.doi.org/10.1109/22.179910.

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9

Thorsell, Mattias, and Kristoffer Andersson. "Fast Multiharmonic Active Load–Pull System With Waveform Measurement Capabilities." IEEE Transactions on Microwave Theory and Techniques 60, no. 1 (January 2012): 149–57. http://dx.doi.org/10.1109/tmtt.2011.2170090.

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10

Nawaz, Asad A., Minsu Ko, Andrea Malignaggi, Dietmar Kissinger, John D. Albrecht, and A. Cagri Ulusoy. "Harmonic Tuning of Stacked SiGe Power Amplifiers Using Active Load Pull." IEEE Microwave and Wireless Components Letters 28, no. 3 (March 2018): 245–47. http://dx.doi.org/10.1109/lmwc.2018.2801027.

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11

Deshours, F., E. Bergeault, L. Jallet, and B. Huyart. "An active load-pull measurement system using two six-port reflectometers." Microwave and Optical Technology Letters 7, no. 14 (October 5, 1994): 679–84. http://dx.doi.org/10.1002/mop.4650071415.

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12

Colangeli, Sergio, Walter Ciccognani, Patrick Ettore Longhi, Lorenzo Pace, Antonio Serino, Julien Poulain, Rémy Leblanc, and Ernesto Limiti. "Source/Load-Pull Noise Measurements at Ka Band." Energies 14, no. 18 (September 7, 2021): 5615. http://dx.doi.org/10.3390/en14185615.

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This paper is focused on the extraction of the noise parameters of a linear active device by exploiting both forward and reverse noise power measurements associated with different terminations. In order for load-pull measurements to yield a significant marginal improvement (as compared to forward measurements only) it is expected that the device under test should appreciably deviate from unidirectionality. For this reason, the source/load-pull technique is applied to frequencies at which the considered devices are still usable but their reverse noise factor exhibits a measurable dependence on the output terminations. Details on the test bench set up to the purpose, covering the 20–40 GHz frequency range, are provided. A characterization campaign on a 60 nm gate length, 4×35 µm GaN-on-Si HEMT fabricated by OMMIC is illustrated.

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13

Di-Luan Le and F. M. Ghannouchi. "Multitone characterization and design of FET resistive mixers based on combined active source-pull/load-pull techniques." IEEE Transactions on Microwave Theory and Techniques 46, no. 9 (1998): 1201–8. http://dx.doi.org/10.1109/22.709457.

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14

Hashmi, M. S., J. Benedikt, and P. J. Tasker. "Impact of Group Delay on the Load Emulation in Multi-Tone Active Envelope Load-Pull System." Australian Journal of Electrical and Electronics Engineering 7, no. 1 (January 2010): 83–88. http://dx.doi.org/10.1080/1448837x.2010.11464260.

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15

MacKinnon, Scott N., and Christopher L. Vaughan. "Effect of the reach distance on the execution of one-handed submaximal pull forces." Occupational Ergonomics 5, no. 3 (March 7, 2006): 161–72. http://dx.doi.org/10.3233/oer-2005-5304.

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This study examined the effects of reach distance on the lumbar spine kinematics and electromyographical activities (EMG) of eight selected muscles of the trunk and shoulder during submaximal horizontal pulling exertions (12% of lean body mass) all located at elbow height. Eleven healthy male volunteer subjects were asked to pull on a load located at varying distances (10, 15, 20, 25, 30, 35 and 40% of subject stature) from the frontal plane containing the load handle. Trunk kinematics in the sagittal plane, as monitored by a Lumbar Motion Monitor, increased significantly as reach distance increased. EMG data revealed increasing erector spinae activity as reach distance increased and this muscle group was found to be co-active with external oblique muscles during the exertion. Shoulder complex muscles were found to be highly active in all conditions, but only the trapezius and deltoid demonstrated significantly decreasing activity as pull reach increased. These data provide some direction in positioning the operator within a workstation demanding pull force exertions.

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16

Raffo, Antonio, Gustavo Avolio, Dominique M. M. P. Schreurs, Sergio Di Falco, Valeria Vadalà, Francesco Scappaviva, Giovanni Crupi, Bart Nauwelaers, and Giorgio Vannini. "On the evaluation of the high-frequency load line in active devices." International Journal of Microwave and Wireless Technologies 3, no. 1 (January 18, 2011): 19–24. http://dx.doi.org/10.1017/s1759078710000838.

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In this work a de-embedding technique oriented to the evaluation of the load line at the intrinsic resistive core of microwave FET devices is presented. The approach combines vector high-frequency nonlinear load-pull measurements with an accurate description of the reactive nonlinearities, thus allowing one to determine the actual load line of the drain–source current generator under realistic conditions. Thanks to the proposed approach, the dispersive behavior of the resistive core and the compatibility of the voltage and current waveforms with reliability requirements can be directly monitored. Different experiments carried out on a gallium nitride HEMT sample are reported.

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17

Arthaber, H., M. L. Mayer, and G. Magerl. "An active load-pull setup for broadband signals using digital baseband processing for the active loop." International Journal of RF and Microwave Computer-Aided Engineering 18, no. 6 (November 2008): 574–81. http://dx.doi.org/10.1002/mmce.20333.

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18

Spirito, Marco, Marco J. Pelk, Fred van Rijs, Steven J. C. H. Theeuwen, Dave Hartskeerl, and Leo C. N. de Vreede. "Active Harmonic Load–Pull for On-Wafer Out-of-Band Device Linearity Optimization." IEEE Transactions on Microwave Theory and Techniques 54, no. 12 (December 2006): 4225–36. http://dx.doi.org/10.1109/tmtt.2006.885568.

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19

Wu, Qunfang, Qin Wang, Jialin Xu, and Lan Xiao. "A Wide Load Range ZVS Push–Pull DC/DC Converter With Active Clamped." IEEE Transactions on Power Electronics 32, no. 4 (April 2017): 2865–75. http://dx.doi.org/10.1109/tpel.2016.2577639.

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20

De Martino, Carmine, Luca Galatro, Raffaele Romano, Gaetano Parisi, and Marco Spirito. "Hardware and Software Solutions for Active Frequency Scalable (Sub)mm-Wave Load–Pull." IEEE Transactions on Microwave Theory and Techniques 68, no. 9 (September 2020): 3769–75. http://dx.doi.org/10.1109/tmtt.2020.3005178.

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21

Xian Cui, Seok Joo Doo, P. Roblin, J. Strahler, and R. G. Rojas-Teran. "High Efficiency RF Power Amplifier Designed With Harmonic Real-Time Active Load-Pull." IEEE Microwave and Wireless Components Letters 18, no. 4 (April 2008): 266–68. http://dx.doi.org/10.1109/lmwc.2008.918913.

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22

Başar, Hakan, and Cihangir Tetik. "MODIFIED BRUNELLI PULL-OUT SUTURE TECHNIQUE IN ZONE II FLEXOR TENDON RUPTURE: A FRESH HUMAN CADAVER STUDY." Hand Surgery 19, no. 03 (January 2014): 349–55. http://dx.doi.org/10.1142/s0218810414500269.

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Purpose: The aim of our study is to develop a suture technique that has sufficient strength of active mobilization. Methods: Thirty two fingers of six fresh human cadavers were divided into two groups. Flexor digitorum profundus (FDP) tendons in the study group were repaired by modified Brunelli suture technique and modified Kessler suture technique, while those in the control group were repaired by Modified Kessler suture technique. Flexion and extension movements were performed with 10 N of load, increasing 1 N at a time to the tendons in both groups. Rupture and significant gap formation was evaluated up to 20 N of load. In the study, to evaluate the resistance to active motion, 1000 times flexion and extension motion cycle was performed with a load of 20 N. The succeeding repaired tendons was also tested with flexion and extension movements increasing the load 1 N at a time. Results: In the study group, failure and significant gap formation on the repair zone were not observed after 20 N of load and 1000 times cyclic flexion and extension movements for resisting to active motion. The rupture and significant gap formation was observed on a average load of 98.43 ± 0.47 N. In the Modified Kessler suture technique, on the eight tendons before reaching the 20 N of load for resisting to active motion, and the remaining eight tendons, during the 20 N loaded motion cycle essential for active motion, rupture and significant gap formation was observed. The failure and significant gap formation was observed on a average load of 18.37 ± 1.89 N. It is measured that by accompanying Modified Brunelli suture to the Modified Kessler suture technique, the resistance was increased up to 5–6 times. Discussion: By the Modified Brunelli suture technique, active motion can be started to the finger without a dorsal block sling immediately after the surgery. Clinical Relavans: By the modified technique, the rehabilitation difficulty and joint stiffness will be minimized.

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23

Karlsson, Martin, Jan-Olov Aidanpää, Richard Perers, and Mats Leijon. "Rotor Dynamic Analysis of an Eccentric Hydropower Generator With Damper Winding for Reactive Load." Journal of Applied Mechanics 74, no. 6 (February 8, 2007): 1178–86. http://dx.doi.org/10.1115/1.2723822.

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Asymmetry in the magnetic circuit, around the air gap circumference, in a hydroelectric generator will give rise to a unbalanced magnetic pull. In this paper, a hydropower rotor system is modeled and the influence of electro-mechanical forces due to overexcitation is analyzed. The active power has been kept constant and the rotor excitation has been changed in order to vary the output of reactive power. The electromagnetic field is solved with the finite element method. Two electromagnetic models are compared: one with and one without damper winding. The mechanical model of the generator consists of a four degrees of freedom rigid disk connected to an elastic shaft supported by two bearings with linear properties. It has been found that the unbalanced magnetic pull slightly increases for reactive loads resulting in a decrease of natural frequencies and an increase of unbalance response. When the damper winding is included, the magnetic pull will decrease compared to the model without damper winding, and the pull force has two components: one radial and one tangential. The tangential component can influence the stability of the mechanical system for a range of design parameters.

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24

Angelotti, Alberto Maria, Gian Piero Gibiino, Troels S. Nielsen, Dominique Schreurs, and Alberto Santarelli. "Wideband Active Load–Pull by Device Output Match Compensation Using a Vector Network Analyzer." IEEE Transactions on Microwave Theory and Techniques 69, no. 1 (January 2021): 874–86. http://dx.doi.org/10.1109/tmtt.2020.3034713.

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25

Ghannouchi, F. M., and R. G. Bosisio. "An automated millimeter-wave active load-pull measurement system based on six-port techniques." IEEE Transactions on Instrumentation and Measurement 41, no. 6 (1992): 957–62. http://dx.doi.org/10.1109/19.199442.

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26

Teppati, Valeria, Hansruedi Benedickter, Diego Marti, Marco Garelli, Stefano Tirelli, Rickard Lovblom, Ralf Fluckiger, Maria Alexandrova, Olivier Ostinelli, and Colombo R. Bolognesi. "A $W$-Band On-Wafer Active Load–Pull System Based on Down-Conversion Techniques." IEEE Transactions on Microwave Theory and Techniques 62, no. 1 (January 2014): 148–53. http://dx.doi.org/10.1109/tmtt.2013.2292042.

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27

Suh, I., P. Roblin, S. J. Doo, X. Cui, J. Strahler, and R. G. Rojas. "Measurement-based methodology to design harmonic-loaded oscillators using real-time active load pull." IET Microwaves, Antennas & Propagation 5, no. 1 (2011): 77. http://dx.doi.org/10.1049/iet-map.2010.0062.

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28

Nebus, Jean-Michel, Philippe Bouysse, Jean-Pierre Villotte, and Juan Obregon. "Improvement of the active load-pull technique for the optimization of high power communication SSPAs." International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering 5, no. 3 (May 1995): 149–60. http://dx.doi.org/10.1002/mmce.4570050304.

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29

Ghannouchi, F. M., F. Beauregard, and A. B. Kouki. "Large-signal stability and spectrum characterization of a medium power HBT using active load-pull techniques." IEEE Microwave and Guided Wave Letters 4, no. 6 (June 1994): 191–93. http://dx.doi.org/10.1109/75.294289.

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30

CHAUDHARY, MUHAMMAD AKMAL, JONATHAN LEES, JOHANNES BENEDIKT, and PAUL TASKER. "MULTI-TONE MEASUREMENT SYSTEM WITH THE STATE-OF-THE-ART ACTIVE IF AND RF LOAD-PULL CAPABILITY." Journal of Circuits, Systems and Computers 22, no. 07 (August 2013): 1350056. http://dx.doi.org/10.1142/s0218126613500564.

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This paper reports a refined multi-tone waveform measurement system for the robust characterization and optimization of nonlinear microwave devices when driven by broadband multi-tone stimuli. This enhanced system has the ability to present specific, constant broadband impedances, not only at baseband (IF) frequencies, but also at RF frequencies, particularly, around the carrier and significant harmonics. This functionality is key in studying the effects of out-of-band impedance termination on both short and long-term electrical memory effects. Achieving such comprehensive impedance control across wide modulation bandwidths is also critical in allowing the "emulation" of emerging power amplifier modes and architectures, and the subsequent waveform characterization of devices operating in these complex and often dynamic impedance environments. Initially, the baseband load-pull capabilities of the enhanced measurement system are experimentally demonstrated through the measurement of adjacent channel power (ACP) behavior of a class AB biased 10 W GaN HEMT, in response to a varying baseband load. Complete baseband and RF impedance control is then demonstrated through the emulation and analysis of a modulated Class-J impedance environment, which interestingly highlights the presence of separate optimum baseband impedance conditions necessary for the suppression of individual IM products.

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31

Bensmida, S., E. Bergeault, G. I. Abib, and B. Huyart. "Power amplifier characterization: an active load-pull system based on six-port reflectometer using complex modulated carrier." IEEE Transactions on Microwave Theory and Techniques 54, no. 6 (June 2006): 2707–12. http://dx.doi.org/10.1109/tmtt.2006.874870.

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32

Bergeault, E., O. Gibrat, S. Bensmida, and B. Huyart. "Multiharmonic Source–Pull/Load–Pull Active Setup Based on Six-Port Reflectometers: Influence of the Second Harmonic Source Impedance on RF Performances of Power Transistors." IEEE Transactions on Microwave Theory and Techniques 52, no. 4 (April 2004): 1118–24. http://dx.doi.org/10.1109/tmtt.2004.825713.

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33

Molina-Cesena, Marlon, J. Apolinar Reynoso-Hernandez, M. A. Pulido-Gaytan, J. R. Loo-Yau, and M. C. Maya-Sanchez. "Experimental Investigation of Resistive–Reactive Class-J Mode Using Time-Domain Low-Frequency Active Harmonic Load–Pull Measurements." IEEE Microwave and Wireless Components Letters 32, no. 1 (January 2022): 96–99. http://dx.doi.org/10.1109/lmwc.2021.3113289.

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34

Ghannouchi, F. M., Guoxiang Zhao, and F. Beauregard. "Simultaneous AM-AM/AM-PM distortion measurements of microwave transistors using active load-pull and six-port techniques." IEEE Transactions on Microwave Theory and Techniques 43, no. 7 (July 1995): 1584–88. http://dx.doi.org/10.1109/22.392918.

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35

Benedikt, J., R. Gaddi, P. J. Tasker, and M. Goss. "High-power time-domain measurement system with active harmonic load-pull for high-efficiency base-station amplifier design." IEEE Transactions on Microwave Theory and Techniques 48, no. 12 (2000): 2617–24. http://dx.doi.org/10.1109/22.899021.

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36

Chahine, S. A., B. Huyart, E. Bergeault, and L. P. Jallet. "An active millimeter load-pull measurement system using two six-port reflectometers operating in the W-frequency band." IEEE Transactions on Instrumentation and Measurement 51, no. 3 (June 2002): 408–12. http://dx.doi.org/10.1109/tim.2002.1017708.

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37

Zemková, Erika, Oliver Poór, and Juraj Pecho. "Peak Rate of Force Development and Isometric Maximum Strength of Back Muscles Are Associated With Power Performance During Load-Lifting Tasks." American Journal of Men's Health 13, no. 1 (January 2019): 155798831982862. http://dx.doi.org/10.1177/1557988319828622.

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This study investigates the relationship between peak force and rate of force development (RFD) obtained from maximal voluntary isometric contraction (MVC) of the back muscles and the power produced during a loaded lifting task. A group of 27 resistance-trained and 41 recreationally physically active men performed a maximal isometric strength test of the back muscles and a deadlift to high pull while lifting progressively increasing weights. Peak RFD correlated significantly with the peak and mean power produced during a deadlift to high pull with lower weights (from 20 to 40 kg), with r values ranging from .941 to .673 and from .922 to .633. The r2 values ranged from .89 to .45 and from .85 to .40, explaining 89%–45% and 85%–40% of total variance. There were also significant relationships between MVC peak force and peak and mean values of power produced during a deadlift to high pull with weights ≥60 kg ( r in range from .764 to .888 and from .735 to .896). Based on r2, a moderate-to-high proportion of variance was explained (58%–79% and 54%–80%). These findings indicate that peak RFD obtained from MVC of the back muscles may be predictive of power performance during a lifting task at light loads. In addition to MVC peak force produced by back muscles, the ability of subjects to develop a high force in a short time should be evaluated in order to gain deeper insight into a loaded lifting performance, namely, in those prone to low back pain.

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38

ISHIKAWA, Ryo, Yoichiro TAKAYAMA, and Kazuhiko HONJO. "Experimental Design Method for High-Efficiency Microwave Power Amplifiers Based on a Low-Frequency Active Harmonic Load-Pull Technique." IEICE Transactions on Electronics E99.C, no. 10 (2016): 1147–55. http://dx.doi.org/10.1587/transele.e99.c.1147.

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39

Seok Joo Doo, P. Roblin, V. Balasubramanian, R. Taylor, K. Dandu, J. Strahler, G. H. Jessen, and J. P. Teyssier. "Pulsed Active Load–Pull Measurements for the Design of High-Efficiency Class-B RF Power Amplifiers With GaN HEMTs." IEEE Transactions on Microwave Theory and Techniques 57, no. 4 (April 2009): 881–89. http://dx.doi.org/10.1109/tmtt.2009.2015111.

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40

Bürklein, Sebastian, David Donnermeyer, Michael Wefelmeier, Edgar Schäfer, and Kent Urban. "Removing Fractured Endodontic NiTi Instruments with a Tube Technique: Influence of Pre-Treatment with Various Agents on Adhesive Forces In Vitro." Materials 13, no. 1 (December 30, 2019): 144. http://dx.doi.org/10.3390/ma13010144.

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The aim of the study was to evaluate the adhesive forces for removing iatrogenically fractured endodontic nickel-titanium instruments using a modified tube technique with various pre-treatment agents in combination with a light-curing composite. 120 Nickel-Titanium-Mtwo instruments were cut at its parallel shaft and fixed in a vise with an overlap of 2 mm. The surfaces were treated with different agents: A) GC Metalprimer; B) Prime and Bond active; C) NaOCl (3%); D) citric acid (15%); E) phosphoric acid (37%) and group (F) was not pretreated (control). One end of a matching microtube, filled with light-curing composite, was placed over the instrument and a transmitting glass fiber inserted from the opposite side guaranteed polymerization. Pull-out tests (1 mm/min) were performed and failure load was measured digitally. Data were statistically analyzed using the ANOVA and Student–Newman–Keuls tests. Interfaces were subjected to SEM analysis. Prime and Bond active created significant higher pull-out values (mean 30.5 N) compared to all other groups (p < 0.001) and Metalprimer (18.5 N) was significantly superior to the untreated (12.6 N) and NaOCl (11.7 N) group (p < 0.05). No significant differences were obtained between the other groups (p > 0.05). Thus, adhesives improved bonding to fractured NiTi instruments.

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41

Ali, Firas M., Mahmuod H. Al-Muifraje, and Thamir R. Saeed. "An Analytic Design Approach to Inverse Class-F RF Power Amplifiers." Engineering and Technology Journal 38, no. 2A (February 25, 2020): 211–25. http://dx.doi.org/10.30684/etj.v38i2a.301.

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The design of high efficiency inverse class-F (class-F-1) radio frequency (RF) power amplifiers includes extensive measurements to characterize the RF power device by means of the empirical load-pull test setup. This paper presents an alternative characterization approach based on evaluating the load impedances analytically at the desired harmonic frequencies for a high electron mobility transistor (HEMT) in terms of the internal and package elements of the active device. It additionally provides a method for extracting the parasitic elements of the power device as well as determining the optimum load-line resistance using the transistor manufacturer’s large signal model. A new topology for the output matching circuit is also proposed with its synthetic procedure to present the appropriate harmonic load impedances. To verify this methodology, a 900 MHz inverse class-F power amplifier circuit was designed and its performance was tested with the aid of the Keysight ADS software. The simulation results showed an output power of 38 dBm, a power gain of about 13 dB, DC-to-RF efficiency greater than 87%, and an acceptable level of linearity for both GSM and CDMA modulated signals.

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42

Yang, Fei, Jun Li, Hongxi Yu, Sen Yan, Anxue Zhang, Kaida Xu, and Zhonghe Jin. "Asymmetric Doherty Power Amplifier with Input Phase/Power Adjustment and Envelope Tracking." Electronics 10, no. 19 (September 23, 2021): 2327. http://dx.doi.org/10.3390/electronics10192327.

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In this paper, the design and implementation of a Doherty power amplifier (DPA) are proposed using gallium nitride high electron mobility transistors (GaN HEMTs). Class-F and Class-C modes are combined to obtain an asymmetric DPA. The precise active load-pull controlling of fundamental and harmonic terminations of the DPA is simulated and analyzed, including the parasitics of the transistors. The measurements of the DPA with the phase difference, input power ratio adjustment, and envelope tracking of the auxiliary PA are discussed in detail in order to achieve a competitive performance. A greater than 63% drain efficiency is obtained within the 10-dB input power dynamic range at 2.1 GHz. The peak of the drain efficiency reaches 73%, with a corresponding output power of 46 dBm.

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43

Curutchet, Arnaud, Anthony Ghiotto, Manuel Potéreau, Magali De Matos, Sébastien Fregonese, Eric Kerhervé, and Thomas Zimmer. "On the development of a novel high VSWR programmable impedance tuner." International Journal of Microwave and Wireless Technologies 8, no. 4-5 (May 25, 2016): 723–30. http://dx.doi.org/10.1017/s1759078716000659.

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Impedance tuners are key instruments used for load- and source–pull measurements. They are crucial for any active microwave components, circuits, and systems characterization and optimization. This paper reports theoretical, simulated, and experimental results related to the development of a novel programmable impedance tuner offering high-voltage standing wave ratio (VSWR). After presenting the proposed tuner principle, a fabricated prototype operating at microwave frequencies and based on a 3.5 mm coaxial line is introduced with experimental results. Depending on the targeted frequency band, different pairs of slugs, with optimized length and characteristic impedance, can be used to obtain an optimal VSWR. This first prototype allowed us to demonstrate the interest of the proposed impedance synthesis principle and to identify ways forward to further improve its performances and push forward this promising technology.

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44

Varlamov, O. V. "INTERMODULATION DISTORTION IN VOLTAGE MODE CLASS D SWITCHING AMPLIFIERS WITH RESISTIVE LOAD." T-Comm 16, no. 10 (2022): 4–11. http://dx.doi.org/10.36724/2072-8735-2022-16-10-4-11.

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The development of 5G technologies and the Internet of Things lead to a change in the traditional paradigm of frequency-territorial planning. Indeed, in addition to reducing the distance between base stations of cellular communication, there is a problem of approaching the radio means of mobile devices to them, as well as the problem of uncontrolled convergence of an arbitrary number of radio means on mobile devices. In all cases, intermodulation distortion (name in English technical literature: reverse intermodulation distortion - RIMD) occurs between closely spaced simultaneously operating transmitters. Once in the reception band, they disrupt the normal functioning of radio equipment. Therefore, the requirements for the transmitter's electromagnetic compatibility characteristics are continuously tightened. Class D power amplifiers, in addition to higher efficiency and better quality indicators, may potentially have a lower level of intermodulation distortion. The article deals with intermodulation distortion in previously unexplored class D push-pull voltage switching mode power amplifier with a resistive load. On the developed theoretical approach basis, an analysis was made of the intermodulation distortion levels dependence on the electronic components parameters spread and the circuit operating mode. It is shown that in order to achieve the desired levels of intermodulation distortion, not exceeding -70 dB, it is necessary to ensure the difference in the active elements saturation resistances is not more than 20% and the saturation time deviation from the meander is not more than 2 degrees.

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Chen, Fa-Yi, Zhe-Xian Ren, and Gih-Keong Lau. "Maximal strengths of dielectric elastomer fingers for a passive grip." Smart Materials and Structures 31, no. 4 (March 7, 2022): 045014. http://dx.doi.org/10.1088/1361-665x/ac57b0.

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Abstract Dielectric elastomer minimum energy structures (DEMESs) are useful as low-force robotic grippers; they can sweep a large angle but carry not much load. It was a design dilemma to reinforce the benders without compromising the stroke angle. As a stronger variant of DEMES, a dielectric elastomer (DE) finger can unbend the ‘phalanges’ of a load beam upon activation of the ‘intrinsic muscles’ of the dielectric elastomer actuator (DEA). The DE finger used a uniform tendon hood that raises the tension center of a single-layered DEA and thus enhances the moment generation and load capacity. In this work, we further optimize the structural design of a slender DE finger by mimicking the human thumb profile. This thumb-inspired DE finger has a tapered load beam for hood shaping of multi-layered DEAs with a blunter fingertip. This thumb-up profile greatly enhances the passive lift strength (against a tip weight) by 54% as compared to the earlier rectangular design, at the cost of a 13% reduction in the active stroke. Further, it exploited the axial stiffness to achieve an order-greater pull strength as compared to the lift strength. Finally, the optimized DEMES grippers carried a payload well exceeding the lift strength; they managed to pick an apple of nearly ten times the gripper weight. In addition, a foot of three DE toes hung upside-down to a branch of a horizontal tube while supporting a payload of close to ten times the foot’s weight.

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Akagi, Tetsuya, and Shujiro Dohta. "Development of Wearable Pneumatic Actuator and Multiport Pressure Control Valve." Journal of Robotics and Mechatronics 17, no. 5 (October 20, 2005): 529–36. http://dx.doi.org/10.20965/jrm.2005.p0529.

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Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. Some involve an actuator and a driving device, such as a pneumatic cylinder and a control valve, worn by the user. Such devices must be compact, lightweight and flexible to avoid excessive load on and injury to the user. The purpose of our study is to develop a flexible and lightweight actuator which can be safe enough to be attached to the human body. We proposed new flexible pneumatic actuators that operate even if the actuator is deformed by external force. We tested a push-pull and flexible pneumatic actuator that moves straight and rotates. We proposed and developed a multiport pressure control valve that drives multiple wearable actuators while reducing the weight of the control valve for multiple degrees of freedom of motion.

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Arnaud, C., D. Basataud, J. Nebus, J. Teyssier, J. Villotte, and D. Floriot. "An active pulsed RF and pulsed DC load-pull system for the characterization of HBT power amplifiers used in coherent radar and communication systems." IEEE Transactions on Microwave Theory and Techniques 48, no. 12 (2000): 2625–29. http://dx.doi.org/10.1109/22.899022.

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Wei, Yuzhang, Zehao Wu, Ziyi Dai, Bingpu Zhou, and Qingsong Xu. "Design of a Magnetic Soft Inchworm Millirobot Based on Pre-Strained Elastomer with Micropillars." Biomimetics 8, no. 1 (January 6, 2023): 22. http://dx.doi.org/10.3390/biomimetics8010022.

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Rather than using longitudinal “muscle” as in biological inchworm, the existing magnetic active elastomer (MAE)-based inchworm robots utilize magnetic torque to pull and push the soft body, which hinders its locomotion mobility. In this paper, a new pre-strained MAE inchworm millirobot with micropillars is proposed. The pre-strained elastomer serves as a pre-load muscle to contract the soft body, and the micropillars act as tiny feet to anchor the body during the locomotion. The proposed magnetic inchworm robot features a simple fabrication process that does not require special magnetization equipment. For the first time, the pre-load muscle is introduced in the design of magnetic inchworm robots, making it more like a real inchworm in terms of locomotion mechanism. The locomotion principle and parametric design for the desired locomotion performance have been investigated. Experimental results show that the fabricated magnetic inchworm robot (size: 10 mm × 5 mm, micropillars length: 200 µm, and mass: 262 g) can locomote on a smooth acrylic surface (roughness of 0.3 µm) at the speed of 0.125 body lengths per second, which is comparable with the existing magnetic inchworm robots. Moreover, the locomotion capabilities of the inchworm robot on wet surfaces and inclined planes have been verified via experimental studies.

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Quintelier, Jan, Pieter Samyn, Wim De Waele, and Joris Degrieck. "Online Wear Monitoring of Polymer Matrix Composites." Materials Science Forum 561-565 (October 2007): 635–38. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.635.

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Polymer matrix composites are widely used as bearing materials for heavy load applications. Still fundamental knowledge about the wear mechanisms of these materials and the evolution in time of these mechanisms is lacking. Currently these mechanisms are only analyzed by post mortem analysis. The Laboratory Soete, based on the well-known pin-on-disc test rig, has developed a new test-setup. Instead of the standard composite specimen and steel disc, a rotating composite disc and steel pin is used to be able to have a visible composite wear track. Standard wear and friction measurements will be further combined with vibration measurements. The vibration measurements give valuable information about the pin-disc contact. The combination of all these measurements should yield valuable information on the active wear mechanisms, the occurrence of fiber and matrix fracture, fiber pull out, generated frictional heat, formation mechanisms of wear particles, and the interaction between all these effects.

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Myniv, R. M. "Features of waterproofing of agricultural buildings and structures." Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 21, no. 91 (November 6, 2019): 89–93. http://dx.doi.org/10.32718/nvlvet-a9115.

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High groundwater levels, defects and imperfect drainage systems contribute to the active dampening of stone structures, resulting in their corrosion destruction and accelerated load loss. There are two main sources of capillary pull-up: groundwater level and so-called sprayed water. Analysis of the destruction of stone buildings shows that the major factor in their destruction is the various sources of excessive soaking (up to 50% of buildings) and, as a consequence, salinization. High groundwater levels, defects and imperfect drainage systems contribute to the active dampening of stone structures, resulting in their corrosion destruction and accelerated load loss. There are two main sources of capillary pull-up: ground water and so-called sprayed water. The humidity decreases in the bottom-up direction, as well as from the middle of the wall to its outer surfaces, which means that the capillary suction of water is in effect. Analysis of the destruction of stone buildings shows that the major factor in their destruction is the various sources of excessive soaking (up to 50% of buildings) and, as a consequence, salinization. Waterproofing has a huge impact on the durability, comfort, and cost of operating the facilities. The lack of waterproofing or its destruction, as well as the violation of the wet regime, are the cause of many defects in both individual structures and buildings in general, which require considerable cost. In the case of insulation failure or lack thereof, the soil water seeps through the walls and destroys the plaster and masonry from the outside, and after the capillary movement inside the masonry, reaches the inner layer of the plaster. Depending on the degree of threat, the appropriate type of waterproofing should be used. The quality and durability of the waterproofing layer depend on the strength of the surface preparation. Reliable adhesion to the substrate, solid coating and uniform thickness of the waterproofing coating are ensured by quality alignment, cleaning, drying, priming of the insulated surface, as well as careful preparation and execution of joints, touches and seams. To protect the foundations, walls and columns of agricultural buildings and structures from the capillary rise of moisture, we propose to cut off the inter-wall waterproofing and improve the hydrogeological conditions of the site. Waterproofing materials must comply with European standards and be certified by ISO quality management system.

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