Fast and Accurate Simulation Technique for Large Irregular Arrays

Abstract

A fast full-wave simulation technique is presented for the analysis of large irregular planar arrays of identical 3-D metallic antennas. The solution method relies on the Macro Basis Functions (MBF) approach and an interpolatory technique to compute the interactions between MBFs. The Harmonicpolynomial (HARP) model is established for the near-field interactions in a modified system of coordinates. For extremely large arrays made of complex antennas, two approaches assuming a limited radius of influence for mutual coupling are considered: one is based on a sparse-matrix LU decomposition and the other one on a tessellation of the array in the form of overlapping sub-arrays. The computation of all embedded element patterns is sped up with the help of the non-uniform FFT algorithm. Extensive validations are shown for arrays of log-periodic antennas envisaged for the low-frequency SKA (Square Kilometer Array) radio-telescope. The analysis of SKA stations with such a large number of elements has not been treated yet in the literature. Validations include comparison with results obtained with commercial software and with experiments. The proposed method is particularly well suited to array synthesis, in which several orders of magnitude can be saved in terms of computation time.

Computational electromagnetics for the SKA-Low prototype station AAVS2

“…28 A specific application to SKA-Low is HARP; a description of the method and references to earlier work is provided in Ref. 29. However, this method has not been implemented to date in commercial codes.…”

Impact of mutual coupling between SKALA4.1 antennas to the spectral smoothness response

“…13 Alternative techniques to accelerate the solution of Maxwell equations in the context of SKA1-Low were proposed in Ref. 14. The numerical analysis proposed in this paper (based on the EM solvers FEKO from Altair and Galileo EMT from Ingegneria dei Sistemi) was first conducted for two SKALA4.1 antennas and then extended to a substation (tile) composed of 16 SKALA4.1 antennas.…”

Holographic Calibration of Phased Array Telescopes

“…A common challenge of phased‐array radio telescope systems is the characterization and calibration of the phased‐array antenna pattern, which can change significantly depending on the pointing direction on the sky. Substantial effort has been made to form predictive models of the phased‐array response (e.g., Bui‐Van et al., 2017, 2018; Sokolowski et al., 2017; Sutinjo, O'Sullivan, et al., 2015; Warnick et al., 2018), which in turn requires an accurate electromagnetic model of the elements in the phased‐array, including mutual coupling effects. Work to characterize the element or primary beam pattern of the telescope includes the use of Unmanned Aerial Vehicles (UAVs) with radio transmitters, low earth orbit satellites and astronomical sources (Bolli et al., 2016; Jacobs et al., 2017; Line et al., 2018; Neben et al., 2015; Sutinjo, Colegate, et al., 2015).…”