The EA91 uses high-gain broadband antennas to receive GNSS signals covering GPS, GLONASS, Beidou, Galileo, QZSS, and L-Band. The EA91 uses the total symmetric distribution multi-stage of 3D choke-ring scheme with completely symmetric distribution for higher phase center stability and superior multi-path jamming performance, and it has excellent coincidence performance of phase center and mechanical center.