A5032510753- Radio Astronomy Observations and Technology
- Antenna Design and Optimization
- Astrophysics and Cosmic Phenomena
- Radio Wave Propagation Studies
- Electromagnetic Compatibility and Measurements
- Microwave Engineering and Waveguides
- Antenna Design and Analysis
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Soil Moisture and Remote Sensing
- Precipitation Measurement and Analysis
- Astrophysical Phenomena and Observations
- Microwave and Dielectric Measurement Techniques
- Scientific Research and Discoveries
- Galaxies: Formation, Evolution, Phenomena
- GNSS positioning and interference
- Superconducting and THz Device Technology
- Advanced Antenna and Metasurface Technologies
- Advanced Electrical Measurement Techniques
- Particle Accelerators and Free-Electron Lasers
International Centre for Radio Astronomy Research
2016-2023
Curtin University
2016-2023
LIGO Scientific Collaboration
2019
Radar (United States)
2019
We compute the spherically-averaged power spectrum from four seasons of data obtained for Epoch Reionisation (EoR) project observed with Murchison Widefield Array (MWA). measure EoR over $k= 0.07-3.0~h$Mpc$^{-1}$ at redshifts $z=6.5-8.7$. The largest aggregation 110 hours on EoR0 high-band (3,340 observations), yields a lowest measurement (43~mK)$^2$ = 1.8$\times$10$^3$ mK$^2$ $k$=0.14~$h$Mpc$^{-1}$ and $z=6.5$ (2$\sigma$ thermal noise plus sample variance). Using Real-Time System to...
The Murchison Widefield Array (MWA), located in Western Australia, is one of the low-frequency precursors international Square Kilometre (SKA) project. In addition to pursuing its own ambitious science program, it also a testbed for wide range future SKA activities ranging from hardware, software data analysis. key programs MWA and require very high dynamic ranges, which challenges calibration imaging systems. Correct instrument accurate measurements source flux densities polarisations...
We summarize the activities conducted since 2019 in numerical electromagnetic analysis of one prototype station SKA-Low telescope. Working closely with SKA Observatory, two teams based Australia and Italy have collaborated effectively modeling analyzing AAVS2, which is most recent an installed Western Australia. A comprehensive overview main parameters at element array level obtained different commercial solvers presented. Results for scattering parameters, individual patterns, beams are...
The design and development process for the Square Kilometre Array (SKA) radio telescope’s Low Frequency Aperture component was progressed during SKA pre-construction phase by an international consortium, with goal of meeting requirements a critical review. As part full-sized prototype ‘station’ deployed – Verification System 1 (AAVS1). We provide system overview describe commissioning results AAVS1, which is low frequency telescope 256 dual-polarisation log-periodic dipole antennas working...
Aiming to fill a crucial gap in our observational knowledge of the early Universe, experiments around world continue attempt verify claimed detection redshifted 21-cm signal from Cosmic Dawn by EDGES experiment. This sky-averaged or 'global' neutral hydrogen should be detectable at low radio frequencies (50-200 MHz), but is difficult measure due bright foreground emission and difficulties reaching required levels instrumental-calibration precision. In this paper we outline progress toward...
Abstract We present the first Southern-Hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of low-frequency component Square Kilometre Array (SKA-Low). Since its deployment, has been used for real-time recorded commissioning data. Additionally, a transient searching algorithm executed resulting images. It uses difference imaging technique to enable identification wide variety classes, ranging from human-made radio-frequency interference...
Abstract We provide the first in situ measurements of antenna element beam shapes Murchison Widefield Array. Most current processing pipelines use an assumed shape, which can cause absolute and relative flux density errors polarisation ‘leakage’. Understanding primary is then paramount importance, especially for sensitive experiments such as a measurement 21-cm line from epoch reionisation, where calibration requirements are so extreme that tile to variations may affect our ability make...
The computational electromagnetic modelling of a large radio telescope prototype array for the Square Kilometer Array is described. numerical models, using Method Moments, are characterised by very number unknowns, requiring use fast solution methods and high performance computing platforms. Good agreement has been obtained between results on two different commercial codes. Results both embedded element patterns station beam shown. computed calibration briefly addressed.
ABSTRACT The wide adoption of low-frequency radio interferometers as a tool for deeper and higher resolution astronomical observations has revolutionized astronomy. Despite their construction from static, relatively simple dipoles, the sheer number distinct elements introduces new, complicated instrumental effects. Their necessary remote locations exacerbate failure rates, while electronic interactions between many adjacent receiving can lead to non-trivial Murchison Widefield Array (MWA)...
We describe the design and performance of Engineering Development Array (EDA), which is a low frequency radio telescope comprising 256 dual-polarisation dipole antennas working as phased-array. The EDA was conceived of, developed, deployed in just 18 months via re-use Square Kilometre (SKA) precursor technology expertise, specifically from Murchison Widefield (MWA) telescope. Using drift scans model for sky brightness temperature at frequencies, we have derived EDA's receiver function...
The numerical modelling of the Square Kilometre Array (SKA) Aperture Verification System Version 1.5 is discussed. role this SKA prototype placed within perspective overall project. dual-polarized log-periodic SKALA4.1 antenna elements comprising a station are briefly described, along with some considerations regarding station. Computational simulation aspects considered, and preliminary results shown. An appraisal implications for station-level calibration concludes paper.
Abstract Global 21-cm experiments require exquisitely precise calibration of the measurement systems in order to separate weak signal from Galactic and extragalactic foregrounds as well instrumental systematics. Hitherto, aiming make this have concentrated on measuring using single element approach. However, an alternative approach based interferometers with short baselines is expected alleviate some difficulties associated a such precision modelling receiver noise spectrum. Short spacing...
The current prototype station for the SKA-Low radio telescope consists of a large number antennas quasi-randomly distributed in close proximity to one another. An alternate, more uniform distribution is introduced, and preliminary simulation results are shown. This layout under consideration as possible replacement quasi-random positioning antennas. main motivation this new avoid pairs almost touching each other, which has negative impact on antenna pattern. individual patterns presented two...
We present two methods for measuring the noise temperature of a differential input single-ended output (DISO) Low-Noise Amplifier (LNA) connected to an antenna. The first method is direct measurement DISO LNA and antenna in anechoic chamber at ambient temperature. second simple low-cost parameter extraction device using coaxial long cable. reconstruction from wave measurements with one terminated port discussed detail. successfully applied these Murchison Widefield Array
The SKA will be the largest radio astronomy observatory ever built, providing unprecedented sensitivity over a very broad frequency (50 MHz to 15.3 GHz). SKA-Low - 350 MHz), built at MRO in Western Australia. It consist of 512 stations each composed 256 dual-polarised antennas, and an individual station is pivotal performance entire telescope. answer question title is, it depends. low array, such as station, depends strongly on pointing direction digitally formed beam local sidereal time...
Abstract We present the first observational study of pulsars performed with second-generation precursor stations to low-frequency component Square Kilometre Array (SKA-Low): Aperture Verification System 2 (AAVS2) and Engineering Development (EDA2). Using SKA-Low stations, we have observed 100 southern-sky between 70–350 MHz, including follow-up observations at multiple frequencies for a selected sample bright pulsars. These yielded detections 22 pulsars, lowest-frequency ever published 6...
The sensitivity of a single station is crucial performance characteristic the low-frequency component Square Kilometre Array (SKA-Low). In this contribution, prototype SKA-Low, Aperture Verification System Version 2 (AAVS2), measured at frequencies 70.3, 110.2, 159.4, 229.7 and 320.3MHz presented compared with electromagnetic simulations. data are in good agreement predictions simulations, confirming understanding instrument its accurate representation
A proposed alternative station layout (the "Vogel" layout) for the low-frequency 256 element Square Kilometre Array (SKA) is reviewed, and new embedded pattern results are presented discussed. It noted that Vogel configuration ameliorates previously issues with an earlier layout, but antenna encountered at a higher frequency band.
Aims. This paper extends the treatment of system equivalent flux density (SEFD), discussed in our earlier to interferometric phased array telescopes. The objective is develop an SEFD formula involving only most fundamental assumptions that readily applicable interferometer radio observations. Our aim compare resultant expression against often-used root-mean-square (rms) approximation, ${\rm{SEFD}}_I^{{\rm{rms}}} = {1 \over 2}\sqrt {{\rm{SEFD}}_{XX}^{\rm{2}} + {\rm{SEFD}}_{YY}^{\rm{2}}} $,...
ABSTRACT We present a low-frequency (170–200 MHz) search for prompt radio emission associated with the long GRB 210419A using rapid-response mode of Murchison Widefield Array (MWA), triggering observations Voltage Capture System first time. The MWA began observing within 89 s its detection by Swift, enabling us to capture any dispersion delayed signal emitted this gamma-ray burst (GRB) typical range redshifts. conducted standard single pulse temporal and spectral resolution $100\, \mu$s 10...
This paper presents a framework to compute the receiver noise temperature (Trcv) of two low-frequency radio telescopes, Murchison Widefield Array (MWA) and Engineering Development (EDA). The MWA was selected because it is only operational Square Kilometre (SKA) precursor at Radio-astronomy Observatory, while EDA mimics proposed SKA-Low station size configuration. It will demonstrated that use an existing power wave based for characterization multiport amplifiers sufficiently general evaluate...
BIGHORNS is a total power radiometer developed to identify the signal from Epoch of Reionisation in all-sky averaged radio spectrum at low frequencies (70-300 MHz). In October 2014, system with conical log spiral antenna was deployed Murchison Radio-astronomy Observatory (MRO) and has been collecting data since then. The monitoring frequency interference (RFI) environment future site low-frequency component Square Kilometre Array. We have analyzed almost two years (October 2014 - August 2016...
The initial phase of the Square Kilometre Array (SKA) [1] is represented by a ~10% instrument and construction should start in 2018. SKA 1-Low, sparse Aperture (AA) covering frequency range 50 to 350 MHz, will be part this. This consist 512 stations, each hosting 256 antennas creating total 131,072 antennas. A first verification system towards Verification System 1 (AAVSl), being deployed validated 2017.
This paper deals with the calibration of analogue chains a Square Kilometre Array (SKA) phased aperture array station, using embedded element patterns (one per antenna in array, thus accounting for full effects mutual coupling) or average to generate model visibilities. The is composed 256 log-periodic dipole antennas. A simulator capable generating such per-baseline visibility correlation matrices was implemented, which allowed direct comparison results StEFCal (Statistically Efficient and...