Array beam field is a necessary condition for high frame rate(HFR) ultrasonic imaging system according to the non-diffraction wave theory. However, the sine function characteristic of array beam waves makes it more difficult to weight the ultrasonic wave transmission signal so the transmission system is very complex. To solve this problem, this paper proposes an effective solution. Based on Fourier transform theory, the energy component of the square wave focuses mainly on the fundamental wave. In this paper a kind of square wave with a single value is utilized to weight the transmitted signals from an ultrasonic transducer. Thus only one power signal source and a very simple electronic switch system can be used to achieve this kind of transmission circuit in the HFR system. Experiments show that such an option has little impact on the image quality of the HFR, however it greatly simplifies the HFR ultrasound imaging system.