The mechanical and imaging characteristics of the synthetic aperture systems were analyzed and compared. By the aid of numerical simulation, the configurations and the modulation transfer functions (MTF) of axially symmetrical synthetic aperture systems with single ring and with dual rings were studied. The imaging qualities of these systems were evaluated and compared. A new axially symmetrical synthetic aperture system with 4+2 dual rings configuration was discussed. Its imaging characteristics were described in detail. The images produced by the new system were processed with Wiener filter to retrieve a better imaging effect.