Phased array radio-frequency (RF) systems have a wide variety of applications in engineering and physics research. Phased array designs are proposed as a trigger system for Askaryan-class in-situ ultra-high energy (UHE) neutrino detectors. Located in Antarctica, these detectors will record RF pulses generated by UHE neutrinos via the Askaryan effect. Modelling the response of phased arrays is straightforward in an environment with uniform index of refraction. However, some detector designs call for phased array deployment at depths where the index of refraction is changing. One solution for computing the response of phased arrays in such an environment is computational electromagnetics with the finite difference time-domain method (FDTD). Using the open-source MIT Electrogmagnetic Equation Propagation (MEEP) package, a set of phased array designs are presented and compared to theoretical expectations. Precise matches between MEEP simulation and radiation pattern predictions at different frequencies and beam angles are demonstrated. Given that the computations match the theory, the effect of embedding a phased array within a medium of varying index of refraction is then studied. Understanding the effect of varying index on phased arrays is critical for proposed UHE neutrino observatories which rely on phased arrays embedded in natural ice. Future work will develop phased array concepts with parallel MEEP for speed and complexity enhancements that account for the 3D shape of proposed dipole antennas proposed as the physical RF elements for in-situ detectors.
FDTD methods, MEEP, phased array antennas, antenna theory, Askaryan effect, UHE neutrinos