A Fast Direct Solver for Mutual Coupling Analysis of Large Arrays of Reflector Antennas

TL;DR

This paper introduces a fast direct solver framework for efficient mutual coupling analysis in large reflector antenna arrays, enabling accurate modeling of dense arrays like HERA.

Contribution

It combines a Method-of-Moments approach with a fast direct solver exploiting symmetry and multipole decomposition to handle large, complex arrays efficiently.

Findings

Enabled computation of EEPs for 320-element HERA array.

Achieved scalable analysis on a 128-core workstation.

Demonstrated accuracy and efficiency for dense reflector arrays.

Abstract

Mutual coupling is a dominant systematic effect in dense reflector arrays, imprinting direction-dependent and frequency-dependent structure on embedded element patterns (EEPs) and currently limiting sensitivity in precision radio measurements. Accurate modelling of these effects requires full-wave simulations of structures that are electrically large at both the array and element levels, making conventional approaches computationally prohibitive. We present a Method-of-Moments (MoM) framework accelerated by a fast direct solver (FDS). The rotational symmetry of reflector dishes is exploited to efficiently compress self-interaction blocks of the impedance matrix. Mutual interactions are treated using a broadband multipole decomposition that remains efficient and accurate for closely spaced elements. We demonstrate the method on arrays of tens of reflectors from the Hydrogen Epoch of Reionization Array (HERA) telescope. To scale to larger arrays, the FDS is used to construct macro-basis functions (MBFs) from a smaller representative array and embed them within a conventional MBF scheme. This allows the first computation of EEPs for the 320-element HERA core on a 128-core workstation.