Electromagnetic simulation and beam-pattern optimization of a C-band Phased Array Feed for the Sardinia Radio Telescope

We report on results of electromagnetic co-simulations and beam-pattern optimization of the C-band PHAROS (PHased Arrays for Reflector Observing Systems) Phased Array Feed (PAF) from the primary focus of the 64-m diameter Sardinia Radio Telescope (SRT). We calculated the radiation patterns of a sub-array of 24 PHAROS Vivaldi array elements and propagated them through the reflector. We present the SRT far-field beam patterns obtained by Iinearly combining different PAF sub-array configurations with uniform weights. Furthermore, we used the Conjugate Field Matching (CFM) technique to derive optimum beam weights to maximize the SRT on-axis gain. The results show that the PHAROS array could be used at the focus of the SRT to provide high antenna performance, with high-quality illumination and efficiency greater than 60% across 4-8 GHz.