Abstract: A phased array feed (PAF) is a type of receiving array that places phased array antennas on the focal plane of a radio telescope to expand its field of view and improve observation efficiency. Owing to the mutual coupling effect between elements caused by a tightly arranged feed array, which changes the performance of a PAF, this paper presents a 7 × 7 rectangular feed array model for a 25 m reflector telescope. By adjusting the element spacings, the performance of a PAF with different spacings is comprehensively analyzed with respect to the mutual coupling effect via performance statistics and comparison. This research aims to provide a reference for the preliminary design of a related PAF.