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A Dynamic array Using Spatial Amplitude Modulation With an Asymmetric Wilkinson Power Divider for Secure Wireless Applications

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2023年第12期22卷 3107-3111页

作者： Randall, Jacob R. Abu Arisheh, Amer Merlo, Jason M. Nanzer, Jeffrey A. Michigan State Univ Dept Elect & Comp Engn E Lansing MI 48824 USA

A new method of obtaining directional modulation by implementing antenna array dynamics is proposed. An asymmetric switching feed structure is implemented in a two-element array that supports a static antenna pattern in a desired direction while adding sufficient complex modulation at other angles to mitigate the transfer of information. The dynamic antenna array feeds are calibrated to be in-phase, have a signal feed amplitude ratio of approximately 6.15 +/- 0.1 dB through the design of an asymmetrical Wilkinson divider. The antenna system comprises of a two-state switching matrix using a double-pole double-throw (DPDT) RF switch. Secure communication capability is demonstrated in simulation and experiment by a 2.5 GHz two-element patch array. The communication system uses a 16-quadratic-amplitude modulation single-carrier signal transmitting 48 kb in a pseudorandom bit sequence at a rate of 4 Mb/s. The DPDT switch was controlled using a switching rate of 3 kHz. To isolate the effects of the phase dynamics, the communication system was operating at an signal-to-noise ratio of 33 dB, thus transmitting high power to all directions. A low bit error ratio (BER) of <10(-3) is demonstrated at the desired transmission direction phi <= |13(degrees)| , with higher BER outside this region. A measurement of a static antenna yielded BER =0 in all directions;thus, the bit errors and narrow +/- 13(degrees) information beamwidth were due exclusively to the antenna array dynamics. Performance metrics of this directional modulation technique are compared against previous literature for the reader. Further insights to spurious signals and mitigation are taken into consideration for the equipment and instrumentation of a narrowband signal to validate the technique as a viable "black-box" system implementation.

关键词： Switches Antenna arrays Antennas Antenna measurements Wireless communication Modulation Antenna feeds Directional modulation (DM) distributed array dynamic antennas dynamic arrays secure wireless

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Experimental results of SIS mixers with distributed junction arrays

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IEEE MICROWAVE AND GUIDED WAVE LETTERS 1998年第11期8卷 381-383页

作者： Shi, SC Noguchi, T Inatani, J Irimajiri, Y Saito, T Nobeyama Radio Observ Minamisa Ku Nagano 38413 Japan Natl Space Dev Agcy Japan Tsukuba Space Ctr Tsukuba Ibaraki Japan Minist Post & Telecommun Commun Res Lab Tokyo Japan Mitsubishi Elect Logist Support Co Ltd Kamakura Kanagawa Japan

The heterodyne mixing performance of three respective distributed junction arrays (i.e., a number of super-conductor-insulator-superconductor (SIS) junctions distributed along a thin-film transmission line involving two, five, and ten junctions are measured and compared to their Fourier Transform Spectroscopy (FTS) detection responses, It has been found that distributed junction arrays have rather large a bandwidth in comparison to conventional SIS junction devices, while still keeping a quantum-limited noise performance. Detailed experimental results are presented.

关键词： distributed array mixer SIS

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Real-time mapping of a whole heart chamber using a novel sparse ultrasonic catheter array

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INTERNATIONAL JOURNAL OF COMPUTER ASSISTED RADIOLOGY AND SURGERY 2021年第1期16卷 133-140页

作者： Baram, Alon Greenspan, Hayit Freidman, Zvi Tel Aviv Univ Fac Engn Dept Biomed Engn Med Image Proc Lab IL-69978 Tel Aviv Israel Biosense Webster Israel Ltd 4 Hatnufa St IL-20692 Yokneam Israel

Purpose Atrial fibrillation (AF), the most prevalent form of cardiac arrhythmia, afflicts millions worldwide. Here, we developed an imaging algorithm for the diagnosis and online guidance of radio-frequency ablation, which is currently the first line of treatment for AF and other arrhythmia. This requires the simultaneous mapping of the left atrium anatomy and the propagation of the electrical activation wave, and for some arrhythmia, within a single heartbeat. Methods We constructed a multi-frequency ultrasonic system consisting of 64 elements mounted on a spherical basket, operated in a synthetic aperture mode, that allows instant localization of thousands of points on the endocardial surface and yields a MRI-like geometric reconstruction. Results The system and surface localization algorithm were extensively tested and validated in a series of in silico and in vitro experiments. We report considerable improvement over traditional methods along with theoretical results that help refine the extracted shape. The results in left atrium-shaped silicon phantom were accurate to within 4 mm. Conclusions A novel catheter system consisting of a basket of splines with multiple multi-frequency ultrasonic elements allows 3D anatomical mapping and real-time tracking of the entire heart chamber within a single heartbeat. These design parameters achieve highly acceptable reconstruction accuracy.

关键词： Heart chamber mapping Intracardiac ultrasonic catheter Ultrasonic imaging Atrial fibrillation distributed array

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Fluxbots: A Method for Building, Deploying, Collecting and Analyzing Data From an array of Inexpensive, Autonomous Soil Carbon Flux Chambers

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JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 2023年第6期128卷 e2023JG007451-e2023JG007451页

作者： Forbes, Elizabeth Benenati, Vincent Frey, Spencer Hirsch, Mare Koech, George Lewin, Grace Mantas, John Naisikie Caylor, Kelly Univ Calif Santa Barbara Dept Ecol Evolut & Marine Biol Santa Barbara CA 93106 USA Yale Univ Sch Environm New Haven CT 06520 USA Univ Calif Santa Barbara Dept Comp Sci Santa Barbara CA USA Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA USA Univ Calif Santa Barbara Dept Phys Santa Barbara CA USA Univ Calif Santa Barbara Media Arts & Technol Grad Program Santa Barbara CA USA Mpala Res Ctr & Conservancy Nanyuki Laikipia County Kenya Univ Calif Santa Barbara Bren Sch Environm Sci & Management Santa Barbara CA USA Univ Calif Santa Barbara Dept Geog Santa Barbara CA USA

Soil carbon flux rates are a crucial metric of carbon cycling that contribute to calculating an ecosystem's carbon budget, and thus whether it is a source or sink of atmospheric carbon dioxide. However, soil carbon flux datasets are frequently low-resolution across either space or time, limiting our abilities to identify small-scale ecological contexts that influence soil carbon dynamics. Existing datasets are distributed unevenly, with some soil carbon-rich regions (like tropical grasslands) significantly understudied. We developed an autonomous, inexpensive, do-it-yourself (DIY) soil carbon flux chamber (a "fluxbot") and data processing software. We deployed a distributed array of 12 fluxbots in a long-term experiment in a central Kenyan savanna where it has been logistically impossible to collect high-resolution soil carbon flux data. With this array we collected over 10,000 individual flux estimates over almost two months, spanning the end of a dry season and the start of a wet season. With our successful deployment in situ, we demonstrate the potential for low-cost, autonomous, DIY sensors in improving resolution of soil carbon flux datasets (particularly in under-studied or logistically challenging systems). If implemented widely, such an improvement in data collection capacities could improve our understanding of ecological and climatic drivers of soil carbon flux dynamics on the local to global scale.

关键词： soil carbon flux closed chamber system do-it-yourself distributed array fluxbots ecological heterogeneity

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PATH UNCERTAINTY ROBUST BEAMFORMING 22

PATH UNCERTAINTY ROBUST BEAMFORMING

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22nd European Signal Processing Conference (EUSIPCO)

作者： Stanton, Richard Brookes, Mike Imperial Coll London London England

ISBN: (纸本)9780992862619

Conventional beamformer design assumes that the phase differences between the received sensor signals are a deterministic function of the array and source geometry. In fact however, these phase differences are subject to random variations arising both from source and sensor position uncertainties and from fluctuations in sound velocity. We present a framework for modelling these uncertainties and show that improved beamformers are obtained when they are taken into account.

关键词： robust beamforming distributed array SNR beamformer steering vector mismatch

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Study on Coherent Synthesis of Broadband Time Inversion Signals

Study on Coherent Synthesis of Broadband Time Inversion Sign...

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IEEE International Conference on Automation, Electronics and Electrical Engineering (AUTEEE)

作者： Tian, Siyuan Huang, Jianchong Chen, Qiuju Natl Univ Def Technol Coll Elect Countermeasures Hefei Anhui Peoples R China

ISBN: (纸本)9781538678619

First, a broadband time inversion signal coherent synthesis model is established based on distributed array. On this basis, the change of time domain, frequency domain and auto-correlation characteristics of broadband signal after time inversion is studied. Under the condition of random phase modulation and random amplitude modulation for broadband signal, the variation of the coherent synthetic superposition gain affected by the Time Position Difference of the signal is also studied. The focusing characteristics of broadband modulated signal under the condition of time inversion are preliminarily explored. The conclusion can provide a theoretical basis for the application of time inversion in engineering.

关键词： distributed array Time inversion wave Broadband signal Coherent synthesis

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Nonlinear Distortion in distributed Massive MIMO Systems: An Indoor Channel Measurement Analysis

Nonlinear Distortion in Distributed Massive MIMO Systems: An...

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IEEE Global Communications Conference (GLOBECOM)

作者： Liu, Bin Guevara, Andrea P. Van der Perre, Liesbet Pollin, Sofie Katholieke Univ Leuven Dept Elect Engn Leuven Belgium

ISBN: (纸本)9781728181042

In this paper, we experimentally analyze the spatial distribution of nonlinear distortion in massive MIMO systems with various array topologies and user locations. With an indoor channel measurement, we reveal the spatial distortion distribution of the in-band (IB) and out-of-band (OOB) power leakage in a real-life scenario. We further investigate the power leakage under different antenna array topologies: including uniform linear array (ULA), uniform rectangular array (URA), distributed linear subarrays (DIS). The impact of user location on the per antenna distortion is also visualized. The results indicate that the DIS array configuration achieves the lowest in-band and out-of-band power leakage, which renders the distributed array a potential to reduce the linearity requirement of PAs when scaling up a practical massive MIMO system.

关键词： Massive MIMO distributed array nonlinear PAs power leakage

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Robust Automotive Satellite Navigation Achieved with distributed Groups of Sub-arrays 41

Robust Automotive Satellite Navigation Achieved with Distrib...

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41st Annual Symposium of the Antenna-Measurement-Techniques-Association (AMTA)

作者： Hasnain, Syed N. Stephan, Ralf Brachvogel, Marius Meurer, Michael Hein, Matthias A. Tech Univ Ilmenau RF & Microwave Res Grp Thuringian Ctr Innovat Mobil Ilmenau Germany Rhein Westfal TH Aachen Chair Nav Aachen Germany German Aerosp Ctr DLR Inst Commun & Nav Wessling Germany

ISBN: (纸本)9781728145259

Ambiguous direction-of-arrival estimation is a key problem for uniformly distributed antenna arrays with inter-element spacing exceeding half of the carrier wavelength. The primary reason behind such ambiguity are the grating lobes generated in the radiation patterns due to insufficient spatial sampling. An L-shaped orthogonal arrangement of radiating elements in distributed sub-arrays is an approach that removes grating lobes and consequent ambiguity to a great extent. The reduction of footprint area by distributing the elements across a car also makes it a suitable approach for conformal integration into automotive exterior parts. In order to realize the feasibility of its application in passenger cars, we investigate and evaluate this concept through measurements and digital array signal processing. This paper presents a comparison of L-shaped antenna element arrangements for different spacings between two sub-arrays, as well as a verification of the concept when mounted on a passenger car. For each scenario, the radiation patterns are analyzed and the robustness of the system against a static interferer is verified.

关键词： distributed array automotive antenna satellite navigation direction-of-arrival interference mitigation

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SFMCW ORTHOGONAL WAVE BEAMFORMING CONCEPT FOR distributed ORBITAL SOUNDING

SFMCW ORTHOGONAL WAVE BEAMFORMING CONCEPT FOR DISTRIBUTED OR...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Bienert, Nicole Haynes, Mark S. Schroeder, Dustin M. Beauchamp, Robert M. Stanford Univ Dept Elect Engn Stanford CA 94305 USA Stanford Univ Dept Geophys Stanford CA 94305 USA CALTECH Jet Prop Lab Pasadena CA 91125 USA

ISBN: (数字)9781665427920

ISBN: (纸本)9781665427920

Studies of sea level rise, ice sheet mass loss, and other glacial processes are hindered by the sparsity of observational measurements. Orbital radar sounding of the Martian ice caps has been successfully conducted, showing the promise for orbital sounding of terrestrial glaciers for improved coverage. Concepts for terrestrial orbital radar sounders, such as the distributed Element Beamformer Radar for Ice and Subsurface Sounding (DEBRIS) mission concept, use an array of CubeSats to obtain narrow beam patterns and reduce cross-track clutter. To loosen wireless synchronization requirements, we investigate the application of orthogonal wave beamforming to DEBRIS. We compare orthogonal wave beamforming to traditional phased arrays and investigate Sinusoidal Frequency Modulated Continuous Waves (SFMCW) as an orthogonality scheme for beamforming.

关键词： Orthogonal Wave Beamforming distributed array Orbital Radar Sounding SFMCW Sinusoidal Frequency Modulated Continuous Wave

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Empirical Comparison of Three Versioning Architectures

Empirical Comparison of Three Versioning Architectures

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IEEE International Conference on Cluster Computing (CLUSTER)

作者： Fujita, Hajime Iskra, Kamil Balaji, Pavan Chien, Andrew A. Univ Chicago Dept Comp Sci 1100 East 58th St Chicago IL 60637 USA Argonne Natl Lab Math & Comp Sci Div Argonne IL 60439 USA

ISBN: (纸本)9781467365987

Future supercomputer systems will face serious reliability challenges. Among failure scenarios, latent errors are some of the most serious and concerning. Preserving multiple versions of critical data is a promising approach to deal with such errors. We are developing the Global View Resilience (GVR) library, with multi-version global arrays as one of the key features. This paper presents three array versioning architectures: flat array, flat array with change tracking, and log-structured array. We use a synthetic workload comparing the three array architectures in terms of runtime performance and memory requirements. The experiments show that the flat array with change tracking is the best architecture in terms of runtime performance, for versioning frequencies of 10(-5) ops(-1) or higher matching the second best architecture or beating it by over 8 times, whereas the log-structured array is preferable for low memory usage, since it saves up to 88% of memory compared with a flat array.

关键词： software architecture software libraries software reliability GVR library global view resilience library supercomputer system reliability three array versioning architecture arrays Benchmark testing Libraries Memory management Resilience Runtime Global View Resilience change tracking distributed array log-based data structures multi-versioning Benchmark testing Software libraries Store management Runtime Software reliability Software architecture arrays Resilience Libraries runtime performance ARCHITECTURE FLAT

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