In this study, a novel elliptical widebeam auxiliary antenna is proposed for anti‐interference of satellite communication earth station. The wide beam width of about 180° in horizontal plane (H‐plane) is achieved by increasing the width of the substrate, reducing the size of the ground plane and adding a V‐shaped aluminum frame. And the narrow beam width of about 30° in elevational plane (E‐plane) is achieved by designing a binary element array. Only two auxiliary antennas are needed for sampling to cover interference from any azimuth direction in H‐plane. The antenna is fabricated and measured, and the results are in good agreement with simulation. The corresponding −10 dB impedance bandwidth is about 17% with maximum gain of 6.5 dBi. The 3 dB beam widths are respectively 33° and 178° in E‐plane and H‐plane. Furthermore, simulation and experiment of the proposed auxiliary antenna in interference cancelation system verify its anti‐interference performance. According to sidelobe canceler, an average interference cancelation ratio of about 27 dB is achieved.