Simulations and Tests of Prototype Antenna System for Low Frequency Radio Experiment (LORE) Space Payload for Space Weather Observations

Space Weather (SW) research is a very important topic from the scientific, operational and civic society point of view. Knowledge of interactions in the Sun-Earth system, the physics behind observed SW phenomena, and its direct impact on modern technologies were and will be key areas of interest.&#160; The LOFAR for Space Weather (LOFAR4SW) project aim is to prepare a novel tool which can bring new capabilities into this domain. The project is realised in the frame of a Horizon 2020 INFRADEV call.&#160; The base for the project is the Low Frequency Array (LOFAR) - the worlds largest low frequency radio telescope, with a dense core near Exloo in The Netherlands and many stations distributed both in the Netherlands and Europe wide with baselines up to 2000 km.&#160; The final design of LOFAR4SW will provide a full conceptual and technical description of the LOFAR upgrade, to enable simultaneous operation as a radio telescope for astronomical research as well as an infrastructure working for Space Weather studies.&#160; In this work we present the current status of the project, including examples of the capabilities of LOFAR4SW and the project timeline as we plan for the Critical Design Review later in 2021.

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A Convenient Designing Method of Feed Network at Low Frequency - The Substructure Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.29-32.884 ◽

2010 ◽

Vol 29-32 ◽

pp. 884-889

Author(s):

Hua Wei Zhan ◽

Cai Xia Guo ◽

Yu Zhang ◽

Yun Zhou

Keyword(s):

Network Optimization ◽

Low Frequency ◽

Antenna System ◽

Substructure Method ◽

Feed Network ◽

Cascade Method ◽

Designing Method ◽

Multi Mode

Multimode feed network is an important part of shortwave multimode multifeed antenna system. The design of feed network is a pivotal technique in the process of projecting antenna system. The substructure analyzing method of interconnect-net is based on the substructure matrix database which is formed by converting the net parameters into data. And it characterizes the non-uniform net units through the database directly. Then cascades the known database of the net units by means of ordinary net cascade method, thus performing optimization in the net. In the paper, the Substructure Analyzing Method of Interconnect-net is applied to designing multi-mode multi-feed network, a typical example of multi-mode multi-feed network optimization is given to illustrate the efficiency of the method.

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A Large Decametric Wavelength Antenna Array for IPS Observations of Radio Sources

Symposium - International Astronomical Union ◽

10.1017/s0074180900067905 ◽

1980 ◽

Vol 91 ◽

pp. 403-403

Author(s):

Ch. V. Sastry

Keyword(s):

Solar Wind ◽

Antenna Array ◽

Low Frequency ◽

Antenna System ◽

Radio Sources ◽

The Sun ◽

Low Frequencies ◽

Interplanetary Scintillations

Most observations of interplanetary scintillations of radio sources are made at frequencies around 80 MHz. These observations are limited to regions close to the sun, where the scintillations are maximum at this frequency. It is possible to extend these observations to the weakly scattering regions beyond 1 A.U. by making measurements at low frequencies. We have built a low frequency antenna system at Gauribidanur, India (Lat. 13° 36′ N and Long. 5 hrs. 10 min.), which can be used for this purpose. Although this system will not be dedicated to IPS, we intend to use it exclusively for solar wind observations during periods of interest.

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Science with the Murchison Widefield Array

Publications of the Astronomical Society of Australia ◽

10.1017/pas.2013.009 ◽

2013 ◽

Vol 30 ◽

Cited By ~ 205

Author(s):

Judd D. Bowman ◽

Iver Cairns ◽

David L. Kaplan ◽

Tara Murphy ◽

Divya Oberoi ◽

...

Keyword(s):

Southern Hemisphere ◽

Early Universe ◽

Western Australia ◽

Space Weather ◽

Time Domain ◽

Angular Resolution ◽

Low Frequency ◽

Performance Properties ◽

Square Kilometre Array ◽

Murchison Widefield Array

AbstractSignificant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.

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Low-frequency array active-antenna system

10.1117/12.390437 ◽

2000 ◽

Cited By ~ 9

Author(s):

Gie H. Tan ◽

Christof H. Rohner

Keyword(s):

Low Frequency ◽

Antenna System ◽

Active Antenna

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The space weather station at the University of Alcala

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2021007 ◽

2021 ◽

Author(s):

Antonio Guerrero ◽

Consuelo Cid ◽

Alberto García ◽

Emilio Domínguez ◽

Fernando Montoya ◽

...

Keyword(s):

Undergraduate Students ◽

Space Weather ◽

Low Frequency ◽

Decision Makers ◽

Weather Station ◽

Geomagnetic Disturbances ◽

Case Scenario ◽

Worst Case ◽

The University ◽

Low Frequency Waves

The Space Weather station at the University of Alcala (UAH-STA) is a place for instrumentation that is able to produce useful products and services in a worst case scenario, assuring decision-makers the access to the data and consequently, increasing the confidence to take actions. The current development consists of an antenna to monitor ionospheric disturbances through the reception of very low frequency waves and a magnetometer to indicate the geomagnetic disturbances caused by sources external to the Earth. This work shows the development of both instruments and some examples of ionospheric and geomagnetic events recorded by both of them. This project serves also as a successful story of using space weather as a teaching tool due to the involvement of undergraduate students at final stage of industrial and telecommunication engineering.

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XGBoost Algorithm for Estimating Equatorial Plasmaspheric Mass Density Using ULF Wave Measurements

10.5194/egusphere-egu21-10693 ◽

2021 ◽

Author(s):

Raffaello Foldes ◽

Alfredo Del Corpo ◽

Ermanno Pietropaolo ◽

Massimo Vellante

Keyword(s):

Space Weather ◽

Mass Density ◽

Low Frequency ◽

Automatic Monitoring ◽

Accurate Method ◽

Gradient Boosting ◽

Data Set ◽

Automatic Monitoring System ◽

Wave Measurements ◽

Extreme Gradient Boosting

Monitoring the plasmasphere is an important task to achieve in the Space Weather context. A consolidated technique consists of remotely inferring the equatorial plasma mass density in the inner magnetosphere using Field Line Resonance (FLR) frequency estimates derived from Ultra-Low Frequency (ULF) measurements. FLR frequencies can be obtained via cross-phase analysis of magnetic signals recorded from pairs of latitude separated stations. In the last years, machine learning (ML) has been successfully applied in Space Weather, but this is the first attempt to estimate FLR frequencies with these techniques. EXtreme Gradient Boosting (XGB) is a recent ensemble-based algorithm that is resulted in being highly efficient in regression/classification competitions and many real-world applications. Here we employ XGB for identifying FLR frequencies by using measurements of the European quasi-Meridional Magnetometer Array (EMMA). Our algorithm takes as input the 30-min cross-phase spectra of magnetic signals and returns the FLR frequency as output; we evaluated the algorithm performance on four different station pairs from L=2.4 to L=5.5. Results show that XGB algorithm can be a robust and accurate method to achieve this goal. Its performances slightly decrease with increasing latitude and tend to deteriorate during nighttime. However, at high latitudes, the error increases during highly disturbed geomagnetic conditions such as the storm's main phase. Finally, we compare the equatorial plasmaspheric mass density obtained by XGB estimates with the density profiles by Del Corpo et al. (2019) for a case study, the geomagnetic storm of the 1st June 2013. Our approach may represent a prominent space weather tool included in an automatic monitoring system of the plasmasphere. This work represents only a preliminary step in this direction; applying this technique on a more extensive data set and on more pairs of stations is straightforward and necessary to create more robust and accurate models.

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