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In this paper we present the electromagnetic modeling and beam pattern measurements of a 16-elements ultra wideband sparse random test array for the low frequency instrument of the Square Kilometer Array telescope. We discuss the importance of a small array test platform for the development of technologies and techniques towards the final telescope, highlighting the most relevant aspects of its design...
The Square Kilometre Array - Aperture Array Mid-frequency instrument will be surveying the southern hemisphere skies with unprecedented sensitivity in the mid 2020s at frequencies from 400MHz up to the 21 cm Hydrogen line. The University of Cambridge is developing a sparse random array solution based on log-periodic dipole array antennas within the Aperture Array Design Consortium. This type of array...
In this paper we present the recent advances on the design of sparse arrays using log-periodic antennas for the SKA AA-Mid instrument. The SKA AA-Mid instrument will explore the southern hemisphere sky from ∼400 MHz up to 1.4 GHz with unprecedented sensitivity and survey speed. Large collecting area, low system noise and great survey speed are key to achieve the demanding requirements of the SKA....
The low-frequency instrument of the SKA radiotelescope will be made of large arrays of log-periodic antennas. Their mutual coupling may be strong and needs to be modeled in terms of embedded element patterns. The HARP method is based on Macro Basis Functions and computes their interactions versus relative positions, based on a limited number of explicit calculations in the near field. This paper shows...
We describe the results of test observations obtained with a 5-m single-dish radiotelescope (RT5) using novel planar feeds designed to detect circularly polarized emission in the 1.5 – 3.9 GHz band. The beam of such feeds is wide; nevertheless, solar scans have been successfully done using feeds at the focus of the primary mirror of the RT5. The sensitivity is about 1 sfu at each polarization and...
A design of a log-periodic antenna to cover the Medium Frequency Aperture Array (MFAA) band for the Square Kilometre Array (SKA) is described and the simulated results are presented in this paper. In order to obtain a smaller footprint, which will allow specifying the transition between sparse and dense regimes in the array at high frequencies, a smaller version of the initial model has been developed...
In this paper we introduce a novel type of wide bandwidth branch-line power divider that does not require surface mount resistors, loads at the ports nor bond wires and hence it can be manufactured using traditional 2D photolithography. The circuit is implemented in microstrip technology and its BW is about 40% with a rejection below -14 dB. This divider is implemented on a corporate feeding network,...
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