The invention discloses a radar system using a main antenna as a helical antenna. The radar system comprises a radar main antenna, a first RF network, a first T / R assembly, a first mixing module, a first receiving machine, an antenna control module, a secondary antenna, a second RF network, a second T / R assembly, a second mixing module, a second receiving machine, a driving module, a rotary table and a shaft angle encoder; the radar main antenna and the secondary antenna are both positioned on the rotary table; the radar main antenna, the first RF network, the first T / R assembly, the first mixing module, the first receiving machine and the antenna control module are connected in a sequence; the secondary antenna, the second RF network, the second T / R assembly, the second mixing module, the second receiving machine and the antenna control module are sequentially connected in a sequence. According to the radar system, the design of the main antenna and the secondary antenna enables accurate signal receiving of the radar system, and therefore, the problems like inaccurate receiving caused by error can be reduced; meanwhile, the rotary table is controlled through a code, so that the rotating angle of the rotary table is accurate, and as a result, the accurate signal receiving function can be realized.