Generating low-frequency electromagnetic waves based on high-frequency antenna and illuminating targets with multi-band signals can be an effect way that can not only reduce the physical dimension of a low frequency antenna, but also improve the performance of radar detection. Combining the electromagnetic wave doppler effect principle and the array antenna architecture, a method of generating a low-frequency signal around the illuminated target is proposed based on the controlling of array antenna parameters, including array radiation element signal timing, phase and element spacing. The principles of array parameter design are described. Composite signals are simulated respectively under two typical geometric relationships between targets and array antenna, target located along the array direction and in the direction of 45° scanning angle. The peak sidelobe ratio (PSLR) and integral sidelobe ratio (ISLR) are used to evaluate the quality of the composite signals. Aiming at practical applications, the effects of array element spacing error, phase error and target location error on the composite signal are simulated and analyzed. Under the condition of sparse uniform array, the influence of the radiation element spacing on the composite signal is analyzed. The simulation results show that the harmonic components of the composite signal increase with the radiating element spacing error and phase error growing.